How Can We Help?

Understanding Insulation in Your Van

You are here:
< All Topics

There are three kinds of heat transferance: 1) Radiation from the fire or the sun passing through air or a vacuum, 2) Conduction through the fire-poker or the walls of your van, and 3) Convection which is how heat moves through a body of gas or liquid like the air in your van. Certain insulation’s work with each type of heat. Choose the wrong insulation for the job and you are just throwing away your money.

(On January 22nd I’m moving back to my Ehrenberg camp with probably a fairly large group of people from the RTR. Everyone is welcome to join us! At the bottom of the post are maps to that camp!)
I should have written about insulation earlier in the winter, but better late than never! I constantly encounter misunderstandings about insulation so I want to spend some time on the science of it as well as the practical application. But before we do I want to make it clear that even more important than insulation is sealing your car, van or RV against air-infiltration. Nothing will make you colder than moving air and even if you insulate but air seeps in and blows around you will still be cold. Before you insulate take time to work on all the seals around the doors and windows. Do whatever it takes to keep them tight. But that’s a subject for another day.

Your van is a lot like a house: in the winter the heat wants to conduct through the walls and the way to stop it is with a high R-value insulation. Because of Convection the heat rises and you need the most insulation in the roof. Like a house, in the summer the Radiant heat from the sun comes in through the windows and makes the van hot. Put a Radiant barrier like Reflectix in the window and the problem is solved.


The above graphics illustrates the three main kinds of heat that impact us as vandwellers:
Radiation: heat radiates from the heat source and when it strikes an object transfers the heat to the object. The classic example of this is the sun. Heat leaves the sun, travels through space and hits our atmosphere, travels through it and when it hits the your skin, or the metal skin of the van it dumps the heat into. Or, it hits the glass windows, travels easily through it and dumps its heat directly into the van. Radiation only occurs through air or a vacuum.
Conduction: Occurs when heat is transferred from a warm body to a cool body through some solid material between them. This is what happens in the winter when you have a heater on inside the van. The air inside the van is warm so it wants to get through the walls to the cool air outside. It travels through the walls as conduction. To stop that, you need an insulation with a high Resistance to heat transfer, commonly called an R-value.
Convection: occurs when heat moves through a gas or liquid body. So studying temperatures in the ocean is studying convection. In your van, the warm air rises to the top and pools on the ceiling and the cool air falls and pools on the floor because of convection.
Radiant Barrier: A radiant barrier reflects radiant heat away from an object thus keeping it cooler. A perfect example of this is putting Reflectix in your windows. When the radiant heat from the sun hits it, it bounces away keeping your van much cooler. Or, on the inside of the van, when the radiant heat from your Mr. Buddy hits it, it bounces back into the van. However, if there is anything on top of the Reflectix, it losses all its radiant value and is worthless. If it’s directly against the metal skin of the van or paneling on the inside, the metal and paneling absorb the heat and the Reflectix can’t reflect it. Radiation only occurs through a vacuum or through a gas, not through metal or wood. Heat moving through a solid object is done by conduction and a radiant barrier is worthless against conduction.
R-Values: All materials Resist the conduction of heat through them.  Some do it extremely well and some do it very poorly. We assign a number value to them of their Resistance to the conduction of heat. The higher the number, the greater the Resistance. In this table I give the R-value of some common insulations. For the money, nothing beats styrofoam, although if you can afford to spend just a little more, Polyiso is far better.


It’s a physical law that whenever bodies of air meet each other that the heat in one body wants to migrate to the cold in the other body and the greater the difference in temperatures the greater the force is to drive the heat into the cold. So the greater the difference in temperature, the more force to push the heat through the insulation therefore the more Resistance you need to stop the  conduction of heat. Put simply, you need more insulation in hot areas than in cool areas.
Let’s imagine a scenario; it’s 20 degrees outside so you turn your Mr. Buddy Portable Heater on to warm up. Because of Convection the warm air rises, in an hour the inch of air at your ceiling will be 110 degrees, where you’re sitting in the middle of the van will be 80 and the floor will still be 30. The difference between the inside hot air and the outside cold air at the ceiling is 90 degrees so there is a lot of force to move the heat across. The difference in the middle of the van is 60 degrees so there is a fair amount of force to move the heat across and there is only 10 degrees difference at the floor so there is very little force to move the heat across. Based on that:
1) Insulating the ceiling is very, very important.
2) Insulating the walls is important
3) The floor is unimportant. Insulate it only if you have the extra money.

When I built my cargo trailer, I used 2 1/2 inches of sytrofoam on the roof, 1 inch on the walls and nothing on the floor. I intentionally left the foil face on the styrofoam uncovered. If you have a heat source, the foil will reflect it back into the cabin but if you cover it with paneling it will do no good at all. It also reflects light making my home brighter.

Based on the science, what I did was put 2 ½ inches of insulation on my ceiling, one inch on my walls and none on the floor. The only time insulating the floor pays off is if you devise a fan system to pull the heat off the roof to the floor. That wouldn’t be hard with some PVC pipe and a computer fan. But because I don’t do that so I didn’t insulate my floor. I follow a four part strategy for the floor:

  • I put down throw rugs in the traffic areas so my feet don’t touch a cold surface.
  • I keep my feet elevated out of the cold.
  • I wear dry, synthetic socks and add a second heavy pair of wool or synthetic boot socks over them.
  • When it’s very cold, I wear down booties.


Don’t Miss-Use Reflectix. This is where I see the most confusion, particularly with people totally miss-using Reflectix. Reflectix is a Radiant barrier and works extremely well against radiant heat because it not only shades, it reflects the heat away. So if you want to keep the suns heat out, it’s a perfect choice. However, it has an extremely low R-Value so it does almost no good against conducted heat.
The problem is there must be an air space of at least ¾ inch or more for it to work. Remember, radiant heat only occurs through air or a vacuum and not through solids, so if your Reflectix is directly against the side of the van or plywood or paneling, it has no value as a radiant barrier and has a very low R-value of 1 per inch. Some people refuse to believe that so here is a quote confirming what I’ve said
If an air space is not present or is too small, heat may be able to conduct through the radiant barrier. Since the metal in the radiant barrier is highly conductive, the heat transfer would all be through conduction and the heat would not be blocked. According to the US Department of Energy,“Reflective insulation and radiant barrier products must have an air space adjacent to the reflective material to be effective.”
If you put Reflectix in a window, the radiant heat from the sun easily passes through the glass, hits the shiny metal and is easily passed back outside through the glass. Reflectix is the perfect thing to put in a window! With an air gap, it works well in the wall next to the van sheet metal. Without the air gap it’s money thrown away.
I recommend you NOT put Reflectix on the walls of your van and buy an extra 1/2 inch of styrofoam or Polyiso instead.
Use a High R-Value product to Stay Warm in the Winter. In the winter, heat loss is almost all through conduction and the way to stop it is with high R-value insulation. Because we live in such a small space, we need the highest number we can get so we lose the least amount of space to insulation. By far your best option is Polyisocyanurate commonly referred to as Polyiso. It has an R-value of 6 per inch and if you get the foil-faced kind it’s 7 per inch. If you can’t find it, or it’s too expensive, your next best choice is plain old white, pink or blue Styrofoam. It has a good R-value, is relatively cheap and is very easy to work with. In every way the Polyiso is a little better, but Styrofoam will work just fine on a budget. The Pink or Blue Styrofoam are better than white but not as good as Polyiso. Whatever you get, try to get it with a reflective foil and it will be your vapor barrier and radiant barrier together.
I don’t recommend fiberglass insulation for vans. Fiberglass is great in houses but poor in vans for these reasons:

  • If you compress it at all it loses its insulation value. Because it has a low R-Value, you will be tempted to get more and compress it.
  • It takes too much space inside the van. The most commonly available size is R13 which uses 3 1/2 inches of space. Put that on both walls and you lose 7 inches of precious space in the van! Consequently, you’ll probably compress it and lose much of its R-Value. I strongly recommend Polyiso instead which is a type of styrofoam. It is R6 per inch so 2 inches on each wall gives you R12. Much better!! I just used 1 inch and think that is enough unless you are in extreme cold. I only lost 2 inches of interior space.
  • It can sag because of the vibration of the van.
  • The shaking can make it give off fiberglass particles that make you itchy and get in your lungs.


If you live in cold country and cold is more of a problem than heat then you should insulate, you’ll be glad you did. On the other hand, if you live in a very hot area and cold is a minor issue, you may not want to put in insulation. While it’s true that the insulation will slow down the heat getting into the van, eventually it will get in. If it’s a 100 degree day, and you aren’t running AC of some kind, by the end of the day it will be 100 degrees inside. Once that heat is inside, the insulation won’t let it out and by bed time it will still be uncomfortably hot, probably too hot to sleep. In that case the insulation is hurting you more than helping you because without the insulation the van would have cooled off much better. In that case, it you’re in Florida where heat is a big problem and cold is a minor problem, don’t insulate.

Even snowbirds can't avoid cold and snow.  I took this photo in April in Flagstaff, AZ. The desert was over 100 degrees so I had to move up to ahigher elevation. But there I ran into cold. Stuff happens!

Even snowbirds can’t avoid cold and snow. I took this photo in April in Flagstaff, AZ. The desert was over 100 degrees so I had to move up to ahigher elevation. But there I ran into cold. Stuff happens!



  1. Al Christensen

    “It’s a physical law that whenever bodies of air meet each other that the heat in one body wants to migrate to the cold in the other body…”
    I don’t think that’s quite right. Heat is caused by “excited” molecules — molecules vibrating faster than their natural state. It takes energy to excite the molecules. When cool air meets warm air, some of the energy that makes the warm air warm is absorbed by the cool air. The cool air becomes slightly more excited and the warm air becomes less so. If there’s more warm air than cool, you end up with warmer air. If there’s more cool than warm, you get cooler air.

    • lucy

      It’s the same thing explained different ways ! This blog it’s not a ‘ formal physics class ‘…
      With all respect.

      • Al Christensen

        You’re right. And I didn’t even do a very good job of making my point.

        • lucy

          Al, I’m sorry, I’m such a witch sometimes !! LOL,LOL.
          My regards. Lucy.

    • Bob

      Al, I use laymans terms because of course…I’m a layman!! And not even a smart one at that!

      • John Dough

        Bob, this was actually very informative and tied a bunch of things together that I never thought of. (for example Reflectix behind paneling has no effect on radiant heat – since radiant travels through air only).
        And how much better polyiso is than fiberglass.
        And I’m only halfway through reading it, and I had to thank you for clearing up a few things in my understanding of this subject.

        • Bob

          You’re welcome John. I don’t wan to get bogged down in science but sometimes a little can be suddenly make the light come on as to how things work and the best way to make it happen.

        • Rkilby

          Reflectix behind paneling will work if there is an air gap between it and the van roof or side…

          • Ernest

            How can it? When radiant energy hits the outer shell of the van, the shell absorbs the heat. The majority of radiant heat does not penetrate sheet metal.

      • Yvonne Harris

        good job Bob

      • Chris

        Hi Bob, I’m building out a new van and am extremely worried about condensation buildup that may lead to rust.
        I have read so many different reviews and am a bit confused. I understand having the vapor barrier and why it is important. However I have a question. Would it be best to use the polyiso boards directly up against the van walls? This way the polyiso boards act as a vapor barrier. I can then put the Reflectix directly on the polyiso boards and leave another air gap between the Reflectix and my luan walls. This way I can increase my R-value by using both items.
        Am I correct in understanding that the polyiso boards act as a vapor barrier?

    • MIke

      Hi Bob, Love your work… I am moving back to the Phoenix area and confused about insulation… I will be living in my van for 9 months while working and will be arriving in September 2015. When I start insulation, what should I use?? I am confused and have seen so many different ways… After my initial 9 month stay in the van, The van will be used for my daily driver and then camping on the weekend.
      I read the messages here and sounded like its best to only insulate the floor in a hot dry climate? I will be getting a Ford E250 Cargo van again… During winter, I will be using a MR Buddy for heat in the mornings and evenings before bed.
      Thanks and look forward to possibly meeting up with the RTR 2016

      • Bob

        Hi Mike I suggest using 1 inch of Polyiso foam board insulation. It’s the highest R-value and still relatively cheap. However, if you are going to be in heat a lot, insulation can work against you. 2 of the 9 months (Dec. Jan)you will be in cold in Phoenix, 2 of them will be cool (November and February of them will be cool and the other 5 months it will be hot.
        I think I would skip insulating if I were you. I might jut use Reflectix on the walls with an air gap. That will help both keep it cool in the summer and warm in the winter.

        • Dave R

          On the walls or in the walls?

          • Bob

            Dave, putting it between the walls will save you space inside the van, but be harder to cut and fit. Having it on top of the ribs will also insulate better because you won’t have thermal gaps where heat can travel out through the ribs.
            But i’s a matter of priorities do you want to save the installation time and get better insulation or would you rather have the extra space inside the van? You have to decide for yourself.

        • Jules

          How do you use reflectix on walls with air gap? Can you put reflectix on wood and then face it towards the bat metal of the van? I am trying to figure out how to insulate a van and I’m so confused.

  2. Openspaceman

    Last winter I would over heat the van at night and then turn off the Big Buddy and then get up in the AM and run it again to get it warm again.
    This winter I bring the van up to 65 degrees on high after work and then turn it on low and it stays a nice 75 degrees all nite or whenever I’m in the van. As you know i’m in Wisconsin and I spent alot of time insulating. For the few months that it’s dangerously cold here, I probably burn $80 per month of those 1 gallon propane cans. If I head to Alaska I will definitely switch to the 10 or 20 gallon tanks like you do.
    *Also I have moving blankets on hooks at the back and side doors and on the inside between the cabin and front of van…makes a huge difference. You can get them at Harbor Freight pretty cheap.
    **Learning everyday. I also park next to a light pole in the parking lot so I can stand on the cement base and wipe off my solar panels so I can get every ounce of sunlight on them in the winter. I’ve only had to charge the batteries with a charger 3 times in two winters…so I’m pretty happy about that. Peace.

    • Bob

      Openspaceman, it sounds like you are doing everything just right!Good going!

  3. Douglas

    Where insulating the floor would come into play would be when you are trying to cool the space. I would still use the same amount of insulation on the ceiling as you would in the cold, but adding insulation to the floor to help keep the cold air in.

    • Bob

      Douglas, where does the cool air come from if you don’t have air conditioning?

      • Douglas

        I would like to install some sort of a/c in the trailer or the box of the truck, but it would take too much solar or combination solar/wind/generator to be feasible. I’ll just move with the climate whenever possible. Deal with it otherwise if not possible.

        • Bob

          Douglas, your right, heat is a problem vandwellers don’t have a solution to. Moving with the seasons works really well for me.

  4. Pete

    Excellent article, Bob. I’ve read numerous blogs wherein people document their van conversions. I’d hazard to guess that 75% or more use Reflectix on their van walls. Not only is it a waste of money, but it is incredibly labor intensive. I hope that future van dwellers like myself (my girlfriend and I are planning on fulltiming in late 2015) will heed your advice and spend the money on polyiso (or similar) instead.
    Thanks for all you do for this community. Yours is one of the first blogs I came across we decided to hit the road. Looking forward to shaking your hand one day. Take care!

    • Bob

      Pete, you’re right, most people know nothing about insulation so they just use Reflectix thinking it’s magical. It is when used for it’s intended purpose and next to the wall of a van is not it.
      Thanks for your kind words.

      • Jules

        Bob could you please tell me exactly how you would insulate a cargo van and what materials you would use? I’m going to begin a conversion soon and I’m so confused and have no idea how to proceed. Thank you!!

  5. raz

    i spent a bunch of years as a licensed hvac contractor. bob is 100% correct.
    that is terminology that i used. my minor in college was a physics major. of what value is it to use words that nobody but you understand. the genius at the big box will do a lot better if you use blue or pink foam. they will be lost with extruded polystyrene.
    if you are going to stick a small ac in the drivers window and stay in rv corrals i wouldn’t do anything. just turn on thermostat and let it rip. it may just be me, but i like the light. same if you have electric heat.
    ice cream raz

    • Bob

      Thanks raz.

  6. PJ

    I finally, finally, finally get it! I understood that Reflectix with it’s low R value was not a good choice, but now I feel like I could explain it to someone else. I notice that the cargo van liner kits online seem to feature fiberglass insulation, arrgh. So, I am in NM, and it has been pretty cold here….did y’all in Quartzite get socked with cold weather, hence, lots of talk about R values, lol?

    • Bob

      Thanks Omar, that is interesting. I’m not sure it’s for me though but I’m really glad you pointed it out.

  7. Gloria Brooks

    When I found my current van on this forum, it came partially insulated and converted. I had to finish the insulation myself. Originally, I just slapped on the blue styrofoam and used Gorilla tape for adhesive as per your book with the coaching of another vandweller. I didn’t have anything over top of the ugly styrofoam yet.
    I got it completely insulated and then, I found a gentleman who was willing to put a hole through my back door to slide my long propane hose through for heating in the winter. He had done a professional job converted his own van. It was he who told me that I really needed a reflectix first layer to cover the entire metal skin wall of my van or I would risk getting moisture behind the uncovered parts of my metal walls.
    My heart sank, of course because I had JUST finished insulating to the best of my knowledge and ability. But, I figured he really knew what he was talking about, so, I listened. He told me it would keep moisture from getting behind my insulation and prevent my walls from eventually rusting out. This seemed to make sense because there were a lot of gaps and cracks I could not cut close enough to cover over with the insulation. I had witnessed condensation build up before the van was fully insulated so, I didn’t want to take any chances of moisture reaching into those bare metal spots I could not quite cover over. To me, that all made sense and I bit the bullet, tore out ALL my insulation and re-did the whole job. So, I re-started by sealing the entire van with a first layer of reflectix with an adhesive of carpet tape. Brilliant stuff. Again, I knew this was NOT for insulation value, but to prevent any kind of moisture from slipping into the gaps and cracks that I didn’t not have the skill to get to and or cover over with the styrofoam. During this second insulating job, I also covered over my two long back side windows (which were painted black anyway) with the pink panther fiberglass stuff (above the reflectix). Knowing it was dangerous stuff, I sealed it over with a bed sheet using carpet tape for both to adhere tightly to the van. Then I carefully sealed it all in with more reflectix, which left a natural air gap between the two. Overtop of that went the blue styrofoam (1 inch) drilled into the van wall tightly so as to NOT allow any seepage of the fyberglass. The final touch was a pretty layer of the luann wood paneling overlaying it all. I report to say that the van is well insulated. I don’t have issues with moisture out west, but, the big test would be if I camped back east. I have to say, that I don’t regret using the reflectix layer, because mentally, I just feel my van won’t rust from the inside out, though, that may just be anal and ridiculous. I may be totally wrong having used the reflectix (and ill-warned), and according to this blog, I would be, but, I like extra precautions.

    • Bob

      Sounds like you did good Gloria!

  8. OverTheTopCargoTrailer

    I don’t know about guys, but I have about 3″ all around floor,walls,ceiling. Now I can park in full sun 100 deg F and only use 225 watts to cool a 7 x 18′ trailer. In the winter down to 32F I need zero heating. I have 100% solar heating and cooling with a SEER 19 mini split, works from 7F up to 118F.

    • Bob

      Sounds really good OvertheTop!

    • raz

      would you mind giving me particulars on your split? as in make, model. i don’t need the price, i can get that. if i know what to get. also maybe why you bought what you did. thank you.
      ice cream raz

    • Bill

      225 watts to cool?
      Do u use a swamp cooler? What a/c only uses 225?

  9. Desert Rat

    With all due respect, I don’t think anyone can outdo this guy for insulating his van:

    • Bob

      Desert Rat, it’s amazing what he did isn’t it? He gave me permission to re-post some of his photos so I’ll be getting them up soon.

      • Desert Rat

        Agree – just hope he doesn’t burn the place down. 🙂

  10. Sonny

    I have a question concerning formation of condensation and consequent rust on the insides of the van/cargo trailer. How should you install insulation so you don’t rust out your exterior sheet metal? Thanks

    • Bob

      Sonny, I have to be honest and tell you I’ve never given condensation a thought. There are two ways to go, either make sure it never happens in the first pace, or assume it will happen and make sure it has a chance to evaporate and let it dry.
      I think the worst thing to do is to make it 90% watertight but the water gets in anyway in that 10% and then it can’t get it out. Then it’ll stay a long time and cause rust. If it gets wet and then dries right away, that’s no big deal. So it’s all or nothing.
      If you’re going to put up a vapor barrier I’d recommend one single sheet of heavy mill plastic that covers the whole wall. That’s how home are done. I’d tape it and then when I put up the insulation I would put up a 1×3 board on top and bottom and attach everything to it. That would minimize the holes in the plastic. But, if moisture ever gets in, it will take a very long time to dry, causing a lot of rust.
      You can do what I did and buy an aluminum trailer!

  11. Sherry in MT

    Food does indeed make community come together. Looks like an amazing group of people and the diversity makes for a great time!

    • Bob

      Sherry, the diversity is the most amazing thing! WE range in age from 21 to 81 and every possible way of life and situation. This year we had an especially large number of young people. We’re still mostly older but lots of younger people too.
      A really great group of people!!

  12. Sonny

    Another issue I thought about is the connection between condensation and mold. The propane Buddy stoves create a lot of water vapor in an enclosed space. That is an area of great concern health-wise. How should that issue be addressed? Thanks

    • Bob

      Sonny, I’ve never done anything about it. I lived in my box van for 6 years in Alaska where my Olympian catalytic heater ran 24-7 all winter and as far as I know I never had mold.
      I’m sorry I can’t be more help but I’ve just never done anything about condensation or the risk of mold.

  13. Ron

    Have you ever heard of anyone having any rust issues due to interior condensation over the years?

    • Bob

      Ron, I’ve never have heard of that. But most people don’t do it long enough to cause it.
      Remember too I live in the desert, I don’t have problems with condensation or humidity.

  14. George

    Bob, I remember hearing about conversion vans back in the 60’s and 70’s having wall to wall carpeting (literally having carpet on the walls). I am considering gluing some wool carpeting on the walls and ceiling of my cargo van using indoor/outdoor carpet adhesive. I believe this will help with moisture control and insulation. Also wool is a naturally fire resistant textile which would go great with a Mr. Buddy heater. Thank You Bob for sharing so much of your knowledge and wisdom!

    • Bob

      George, I’ve known people who did that and were happy with it. My concern with it would be keeping it clean and odors out. But if you’re not concerned about that it has lots of advantages.

  15. Matt71

    Regarding moisture, I saw someone post about using water shielding
    Would that actually work? And where would you install it, on the metal or on the insulation?

  16. charles

    What about insulating an aluminum cargo trailer?? The ceiling was done when I bought it and had the foil facing up. I didn’t think that was right, but was going to put another layer in with foil down.????? Also the walls have dead air space between them and aluminum siding. I can’t get them off so I was going to put up 1.5 x 1.5 or 1.5 x 3 and then insulate. I’m just looking for some ideas. Trailer is 8.5 x 20. Thanks

    • Bob

      Charles, it depends, if there is a gap between the insulation and the ceiling it’s good to have it up, it will reflect the suns heat back toward the skin. If it is directly agaisnt the metal, it is a waste of time.
      Another layer with the foil pointing into the body is a very good idea. But if you cover it will do no good.

      • charles

        Bob. Thanks for the reply. I think I get your meaning
        ” But if you cover it will do no good.” I assume you mean I will lose the reflective value, but I would still keep the R-value of the two sheets together. which would be 2, 3/4 sheets and close to r-9.

        • Bob

          That’s right Charles. Radiant barriers only work if they have an air gap, if anything touches them the heat becomes conductive and not radiant so it can’t be reflected. Without an air gap Reflectix has an R-value of 1 which is extremely low. If you have the foil side facing in the van, it will reflect heat back into the van, but if you put paneling on it it stops reflecting heat and the foil itself is worthless.
          But it does no harm to the foam board, it will still have the exact same R-value no matter what touches it.

  17. charles

    great. Thanks for the info….invaluable

    • Bob

      Glad to help Charles!

  18. JannaB

    Howdy Bob,
    Read your blog about insulation and realized I am one of those folks that don’t fully understand Heat types. Sad but true.
    I Pulled all the reflective (easy to install) insulation off. Bought the foil backed 2 1/2 foam and struggled with it for 2 days. It is up! On the ceiling of my 12 foot cargo trailer. Put the reflective bubble wrap on the walls-right or wrong that were it is. So now, let it be winter. I’m a winter kind of girl.
    Thanks for all the information. I have learned so much since finding your site. I Believe all things happen for reasons. ⛄️

    • Bob

      Janna, it sounds like you did a great job, all that insulation will pay off big-time for you in comfort this winter!
      I’m very glad I can be of some help!

  19. charles

    one more question.
    what about Diamond Plate for the interior walls, mounted over the insulation????
    How effective would it be as a radiant barrier?

    • Bob

      Charles, metal transmits heat very easily so whatever value it had as a radiant battier would be offset by transfering heat. Plus, it’s very heavy! I think Reflectix would be a much better choice. But, many polyiso and styrofoam boards come with a reflective foil barrier already on them. They’re the perfect solution.

  20. Mike

    I used tin foil as a vapor barrier, works great. I used spray adhesive from a can, sprayed the metal inside the van, and rolled it on with a small paint roller. Cost me 6 rolls of foil, $18 and 2 cans of spray glue, 10 bucks. Then I installed styrofoam and then glued more foil over it, makes my whole place light up with one strand of LED christmas lights.

    • Bob

      Sounds like you did a great job Mike!

  21. John

    Hi Bob, I’ve been reading your blog for a while now, a lot of great information here. Working on a 95 GMC Vandura, and have plans to pick up a trailer soon. Have you had any experience with ceramic paint insulation, I’ve been looking at a product called lizard skin. It says it can reduce temperatures by 30 degrees. Your input would be great. Thanks John

    • Bob

      John, I’ve heard of it but I haven’t formed an opinion on it. I’m skeptical but just on general principles. If it isn’t too expensive you don’t have much to lose. If your van isn’t white, painting it white will make a big difference. If nothing else I’d paint the roof, I’ve done that before and it does help. Maybe start with just getting enough ceramic paint to do the roof and see if that helps.

  22. Ken

    Bob, I have a Sprinter van which has bare walls that I use to haul my artwork to art festivals. There are a few times when I am in hot climates but most of the time, I am fine with general conditions. I plan to install a Fantastic Fan to have airflow to remove heat and help sleep at night.
    My question is this. As I was looking at insulation options should I just as well slap some plywood on the walls and ceilings and call it good?
    I am not a full time RV’r but I do sleep in the van 40-60 nights out of the year to avoid staying in a hotel. I am just looking to stay comfortable at night. Any thoughts would be appreciated

    • Bob

      Ken, a big part of the answer is will you mostly be out in the summer or winter. If you are mostly worried about heat, your best bet is Reflectix in the walls and on the roof. Be sure to leave a 1/2 inch air space between the wall and Reflectix. It will keep out a lot of heat in the day, but then let out the heat at night when insulation would keep it in. The Reflectix won’t help keep it warm in the winter.
      For heat, the Fantastic fan is most important! You might think about two of them, one set to blow in and one set to blow out will give you a draft and move LOTS of air!
      If you are mostly worried about cold, use insulation like polyiso instead.
      Why plywood on the walls/ceiling? It won’t help with heat/cold but you can use it to attach things to the wall.

      • Ken

        Thanks Bob. I was using plywood more to protect the van walls from stuff banging into them and denting the metal from the inside.
        If I use Reflectix, would I be better to secure it to the plywood and then mount the plywood to the van rails? This would give an air space of about 2 inches from the van wall.
        Thanks for the help.

        • Bob

          Ken that would work great. The Reflectix will do little to keep heat in the van so you can mount it directly to the plywood.
          So I assume that means you aren’t concerned with cold,just the heat?

          • Ken

            Hi Bob,
            Out of the 40-60 days a year I bunk in the van, less than a dozen are those nights below freezing. Most nights are in the 45-60 degree range which my REI sleeping bag is just fine. Most days are 70-90 degrees
            Another option I was considering was using 1″ polyiso foil backed in-between the rib sections of the walls and ceiling. I could still leave an air gap of about 1″. However, I thought that might work against me based on the temp range that I am in most of the time. Thoughts?

          • Bob

            Ken, I think the Reflectix would be better for you since heat is your major concern. Once the sun goes down the Reflectix will allow the heat to escape while the poly would hold it in the van. If it was 90 during the day with poly it could still be 80 at bedtime but with reflectix it will be outside temeratures–much cooler.

  23. Max

    Hi Bob, very interesting article explaining the principles.
    I’m about to insulate my conversion van and would like to know which route to take.
    I’m in Florida and always camp along the state, most of the times Florida Keys…in summer!
    I read all the article and comments and for summer you recommend NOT to insulate or at least add reflectix with the foil facing the van wall and the proper air gap?.
    You also wrote ” if you’re in Florida where heat is a big problem and cold is a minor problem, don’t insulate”.
    I always run an a/c with shore power at camps.
    I believe if I use Polyiso/styrofoam against the inner walls and reflective sun shades on the windows it will be ok. Isn’t it?
    Correct me if I’m wrong.
    Thank you!

    • Bob

      Hi Max, yes, if you have A/C then you should insulate with polyiso which will greatly reduce the amount of time the A/C runs. The reason I said don’t insulate in the heat is because few vandwellers have access to A/C on a regular basis and without it you are better of without it.
      Reflectix is still a good idea of you have room in your walls. From the sheet metal you would eave a 1/2 inch air gap, then the Refletix and then the polyiso into the van, and you will probably put paneling on over it.
      The Reflectix will keep the heat out while the polyiso will keep the cold from the A/C in. Good combination!

      • Erik

        Hi Bob! What if one were in a hot, dry climate in a van and was running an evaporative cooler? Would the polyiso reduce the time the evaporative cooler would need to run? Thank you!

        • Bob

          Erik, to be honest with you I’m not sure. Normally I don’t recommend insulation for hot areas where you are not worried about cold because it hold the heat in at night. But if you have air conditoning then insulation is a good idea. It’ll keep the cold you create in.
          My guess is that it doesn’t matter how you create the cold, but that’s just a guess.

  24. Brian

    Hi Bob. I have a 1988 Astro passenger van and need to insulate it to weather a lot of cold nights in Colorado. What should I do?

    • Bob

      Brian here are some ideas:
      1) Put Reflectix in all the windows
      2) Hang a barrier between the back and driving area. Use heavy curtains, blankets or even an old sleeping bag to keep the heat in back.
      3) Hang a barrier over the back door using the same things as the divider curtain.
      4) Weatherstripping to prevent all drafts.
      5) Ideally, you’ll pull off all the plastic trim and put up polyiso insulation on the walls and roof, but most people aren’t willing to do that.
      The big thing is to get a MR Buddy heater and have a source of heat.

  25. Brenda

    Bob…I want to insulate (against the cold) my E150; so that when I get spooked while camping solo (my dog died), I can get into the van to sleep. What do you think about using the Ultra Touch Denim Insulation Hot Water Heater Blankets as temporary insulation…at least for the ceiling? It DOES come with the reflective side. It is light, R6.7, and fairly inexpensive.
    I am mostly a southern tier state camper, but it can get very cold at night in Big Bend, and areas of New Mexico….
    What do you think? The reflective layer will face the INSIDE of the van…as you said…not against the van walls. And when I do not require it (in warmer climes) I can remove and roll it up for use another cold day?
    Your thoughts?

    • Bob

      Brenda I’m very sorry you lost your dog, I know how devastating that can be. I’ve never heard of this before but from what I saw on Amazon I would not get it. I’d be very concerned the cotton will absorb moisture and lose all it’s R value and mold or mildew. Reflective material is just not good in walls, you’d be much better off with styrofoam.

  26. Kennyboy

    Hi Bob,
    Sure learned a lot about insulation from your article and people’s letters! 2 questions: I’m not understanding one thing about reflectix: If you need an airspace between it and the vehicle’s interior wall, how is it you can put it directly against a window? Is glass a conduit for radiant heat as is air?
    Secondly, Since I camp here in So. AZ in my little trailer, would I be better off putting foil backed foam in the windows, as I run the AC in the summer (either shore power at a state park, or via generator) but I also camp in the winter. AZ has some cold places as the Flagstaff photo of your outfit illustrates. I camped at Parker Canyon Lake, only 80 miles from Tucson, over New Years one time and my outside thermometer read 18 degrees one snowy morning, for example.
    Thanks again for your website, articles, & blogs!

    • Bob

      Kennyboy, you’ve got it right, the Reflectix works well in glass because the radiant heat easily passes through the window and hits the Reflectix and then easily passes back out again. On the other hand, when the heat hits the metal skin of the van it stops being radiant heat and some of it passes through and becomes radiant again. With an air gap the Refletix will do some good, but nowhere near as much as real insulation would.
      Yes, foil backed foam works extremely well in windows. Many people a layer of Reflectix next to the window and then a layer of styrofoam or polyiso on the inside of it. That is ideal!
      It’s been an unusually cold winter here!! Insulation really helps!

  27. Tigger

    Hello Bob I’m just starting my van life journey and find this article indispensable as I’m buying insulation today among other things. I think I’ll be passing your way in the next week or so and thought I’d stop by,I hope to meet you. I’ll be the woman with the people hair in the cargo van hahaha. Again that’s a million for the concise layman’s explanation. Tigger

    • Bob

      Tigger, please stop by! There are about 150 of us here and you can meet lots of great people and make many new friends!

  28. Tigger

    Hello Bob Ita Tigger and I’m in the desert by flying j but Frank says your in quartz so I guess we’ll see each other another time.

    • Bob

      Hi Tigger, yes, the RTR is going on now in Quartzsite so I am over here. Sorry to have missed you.

  29. Lance

    I’ve read through this EXCELLENT post and all of comments.
    I have a Ford E150 cargo and will use it for summer travel, so I’m really only concerned about keeping it cool – most of the time only in the evening/night since during the day I’ll be out sightseeing or driving with ac/the windows open.
    It sounds like the best option would be to use Reflectix with an air gap between it and the metal walls?
    But really, how effective is this? I’m having trouble reasoning through this… surely over the period of the day the battle will eventually be lost and the van will heat up at which point I have to open windows and vents to the outside and start circulating the air, so at that point, isn’t it true that it doesn’t really matter if I have Reflectix or not?
    Or am I thinking wrong – even when the van has heated up, the Reflectix is still actually making it much LESS hot than it would otherwise be?
    I’m wondering if I should just not bother with Reflectix in favour of simply working hard on a way to circulate the air well?
    (And if so, any good ideas on circulation without solar/battery system as I’m trying to avoid getting into installing a power system? 🙂
    Thanks for your wisdom!

    • Bob

      You’re right, on a hot enough day the heat is going to get in anyway but the Reflectix will let it back out at night. There will be some days in the year that it will delay it long enough so it never gets too hot, but how many times a year I can’t even guess and whether it’s worth it to you is for you to decide. Since you only travel and not full-time I’d guess it wasn’t worth the extra money and work

  30. Judy

    Hi Bob,
    I have just bought a 2013 Ford Transit Connect that I am going to convert into a small RV. I live in New England and camp May – October. Do I need to bother with insulation at all? I am planning on buying/making screens for windows and doors so I can have them open at night.

    • Bob

      Judy, as long as you’re sure you will never camp in it in the cold, then no, you don’t need insulation. But if your circumstances ever change, will you regret not doing while it was easy?

  31. Ri Johnson

    Hi Bob,
    Do you have any advice/suggestions for someone who is planning to do live in a chevy express cargo van and travel across the country for a year? I’m from Houston, Texas so I was not going to insulate at all and only add sound deadening and reflectix along with my roof vents but I do not want to be limited and plan to visit places up north and even Canada. Thanks so much for any advice.

    • Bob

      Ri, if your main concern is heat then the Reflectix (with a dead air space) is what you want. If you are equaly concerned with cold then you should get insulation as well, so you’d want these layers starting at the sheet metal
      sheetmetal->Dead air space->Reflectix->1 inch sheets of polyiso foam insulation or styrofoam.

      • Zbik

        Bob, you said: sheetmetal->Dead air space->Reflectix->1 inch sheets of polyiso foam insulation or styrofoam.”
        I was thinking to put the insulation on first and then the Reflectix to make sure the Reflectix does not touch bare metal:
        Will this work?:
        sheetmetal>rattletrap sound deadener>insulation>reflectix
        I just don’t see how I would install Reflectix with an air gap and then insulation without building some sort of paneling wall to slip all this stuff inside.
        Thank you for your help in advance!

        • Bob

          I’m not a fan of Reflectix on the wall, the polyiso is all you need. Save yourself the money and skip the Refletix. It has an R-value of less than 1, Polyiso is R-Value 7 for 1 inch.

          • Zbik

            What’s your opinion on the FatMat Rattle Trap and other sound deadeners? I’m more concerned about keeping outside noise out then noise while driving. I see people installing it but it’s very expensive. Not sure if it’s worth it and I can’t seem to find any info on whether it helps with outside noise. Thanks. -Zbik

  32. Geva

    GREAT site! I’ve spent the last few days reading everything I can. I lived in a station wagon for about a year, and half my reading was nods of recognition, but I also picked up some new ideas. I’m about to embark on a DIY RV project; the vehicle is a step van, and the insulation – tentatively – reclaimed 4″ polyiso (R30 or so). It’s a huge step up (get it?) from the car, and even with 8″ gone it’s still cavernous by comparison.
    On the other hand, I’ve found 98% of houses in the US inadequately insulated (my frames of reference are Iceland and Norway), and been inspired by things like the Passivhaus and R-2000 standards. What I learned from studies made on hyperinsulated buildings is that as R-values go up, so does the importance of ventilation. So with that in mind…
    Regarding your caution against using too much insulation in hot weather: the armchair thermodynamicist in me says if I have large vents that can seal tightly, then keeping them closed during the day and open at night should outright cure the heat-trapping problem that insulation would otherwise cause.
    This comes partly from armchair physics, and partly from my experience living in a flimsy shack of a house in California (that still cost $2400/mo…don’t get me started…). During the winter (humid, damp, highs/lows about 15/5C) it was straightforward – burn lots of wood, keep the doors closed, and complain; no two ways about it. In the summer (pretty dry, highs/lows 35+/10C), we kept the doors open at night and closed during the day. This system worked absolute wonders, with the caveat that the house was in the shade after 10am. It had, to my knowledge, absolutely NO insulation apart from single-pane glass and two layers of wood siding. I figure replicating that system in a well-insulated van, perhaps using large, well-sealing floor and ceiling vents, and maybe a push/pull fan system on them, should work just as well even if I have to park in the sun.

    • Bob

      All the things in your van are going to act as thermal mass and collect and hold the heat during the day and then at night they are going to release it at night. That is the idea behind passive solar heating. The ground around the van will be releasing its heat all night a well.
      My experience has been that no, ventilation a night does not keep up with those two things if you have insulation in the walls.

  33. RustyGuy

    My Gosh this is the most valuable thread! Bob you should have a paypal account for tips on your advice (or do you have one already?). Got an old iveco Italian truck with fiberglass shell and 2 rollup doors so I assume foil backed foam w/a 3/4 wood rail ceiling (for gap)and walls and maybe Reflectix attached w/spray glue over the 2 accordion style side and back rollup doors?? Hmmmmm.
    Its a fiberglass shell so not sure the best approach here.
    Mostly concerned with cold climates. And the sleeping bag idea was great for the front/back separation!

    • Bob

      RustyGuy, I’m very glad to help! I recommend foil backed polyiso sheets as the best insulation for most things, including your fiberglass shell. Remember, that unless you leave an air gap betwen the Refletix and the heat source, it does no good at all–money thrown away.

  34. RustyGuy

    I have a ton of rmax polyiso 1.5 inch sheets foil both sides. If I got this right best to line the fiberglass shell with wood rails to allow that gap and attach poly sheet to rails to prevent overhead sun conduction in hot climates? The whole shell is straight hard fiberglass like a van top.
    But if only concerned w/cold climate could technically attach poly flat right to walls as that would keep the same heat in and avoid the rails? Or maybe happy medium would be flat to walls but wood rails to ceiling?
    2 rollup (delivery truck style) doors on tracks (side and entire back like a ups truck) fold up overhead…so going to be much loss there. Is the heavy sleeping bag/curtain concept the only way the address that one?
    Any last words before I commit? 🙂 Thanks!

    • Bob

      RustyGuy, yes, you have it figured out right. For heat add the air gap and just for cold don’t bother. Just he air gap in the ceiling might be the best thing since mot of the heat will come in through the roof. How are you for headroom, can you lose another 3/4 inch?
      The ideal way to insulate just the back from the cab is to build a wall (with a door) and put the polyiso on it. But you can’t always get ideal so the blankets.sleeping bags are a good compromise. If you’re in a lot of cold, then you might consider a vapor barrier between the front and back. The warm moist air from the living area will cause a lot of frost inside the front glass.

  35. RustyGuy

    Wow thank you. That is exactly what I would have learned after my first winter… (a little late). Never even considered another more standard type door. And i now see without the vapor barrier there will be much moisture.
    Again very much appreciated for lending your considerable experience to my situation. (and do feel free to forward your pp info if your wish ;)).
    Many regards

    • Bob

      Thanks Rustyguy! I learned the hard way about living in a van in extreme cold.

  36. RustyGuy

    Another thought. Have you ever seen pvc strip door (the curtains used in grocery store meat freezer entrances) as either a vapor barrier or possibly in front of a rollup door? Have rolls of that stuff around too. You can walk right through it. But from what I can look up its an r value of less than 1. It certainly takes very little space, is easy to hang and cut strips. I wonder if its just toxic and of little value. I dunno.

    • Bob

      Rustyguy, it’s not something I would do, but I don’t know much about it. Too many negatives and few positives.

  37. Robb Stein

    I have a normal van I’m fixing to make my home soon as I travel this great country of ours. I definitely going to be using reflectix in all the windows, cutting it out to the size of each window. That sounds easy enough.
    And then at minimum I was thinking of using reflectix for the ceiling, possibly the walls too. When using it for walls/ceiling, does it matter if there are any gaps for hot air to seep through on the sides? Or does it have to be completely sealed off?
    If I do the walls, the windows, which are recessed, are already covered, so I was thinking just to have the insulation about 3 foot high coming from the floor. It would have the 1″ air gap from the wall and just be open on the top of it. Does that make sense? Would that work?
    That would allow for me to use the cup holders and cubby holes. But Perhaps I’ll need to cover all that up too?
    For my A/C I was gonna make up a redneck A/C with ice, a cooler, fan, water pump, and tubing.

    • Bob

      Robb, Reflectix is great in windows-great choice. But, it only works in walls or ceilings with at least a 1/2 inch air gap. If you give it that it will help in the heat, but do little or nothing in the cold. If it isn’t sealed around the edges, the heat will just flow through to the openings and come inside. It would lo down the heat from coming in, but eventually it will come in. If you are only going to cover part of the wall, cover the top part–warm air rises. It will probably have little value.
      The redneck cooler will work–in dry areas. It won’t do much in humid areas but make it more humid.

      • Robb Stein

        For the cooler I was thinking some that contained the ice so it wouldn’t get humid, like this:
        That sucks about the reflectix. Maybe I’ll just put some on the roof of the van so the heat will stay away. Or make me a cover I can put out on the sunny side when I’m parked. Thanks for the input!

      • Robb Stein

        For the cooler I was thinking something that contained the ice so it wouldn’t get humid, like this:
        I was thinking I could use the melted water for tap water too.
        That sucks about the reflectix. Maybe I’ll just put some on the roof of the van so the heat will stay away. Or make me a cover I can put out on the sunny side when I’m parked. Thanks for the input!

        • Bob

          Robb, putting the reflectix on the outside of the van works extremely well!! That way the heat never gets inside of it, but when the sun goes down the van cools right off. I highly recommend it!

  38. Gene Wells

    Hi cousin Bob ( I’m sure if we went far enough back in our ancestry we would find we are cousins) There is a heavy weight plastic that is often used to put under the laminated flooring that at first I was thinking I would encase the whole van in. But got to thinking that a cargo van with no windows is pretty well immune to air leaks anyway, so have set that idea aside. I’ll just do the reflectix with air space and then the polyiso sealed with the alum. tape and leave it like that. Was going to cover it with a wood finish but maybe not. I think I have gotten answers from all the reading I’ve done, but – – I’ll be starting from bare walls and am wondering why I have not heard of spray foam to fill the odd shaped void between the inner wall of the van and he outside wall. Is there something I don’t know about the spray, does it out gas some vapors that are bad, or is it to sticky/messy to work with or ??. Thanks for all the information. Hope to see you in a few months.

    • Bob

      Hi new cousin Gene!! It depends on what you mean by spray foam. If you mean the cheap spray foam you buy at Home Depot like “Great Stuff” it is a VERY BAD IDEA to use it in your van. For some reason I can’t remember, it will rust out your walls very quickly. Don’t use it!
      But the professionally blown in stuff is highly recommended! I has an exceptional R-Value and from everything I’ve heard it is safe–but there are people who would strongly disagree. But, it is very expensive so most people don’t spend the money. You can get kits of that stuff that you apply yourself and save a lot of money–but it’s still expensive and a pain to put on. But, when you are done, it is by far the best insulation job!
      I still just recommend polyiso as the best all around balance.

  39. Josh

    Thanks Bob,
    I think you just saved me a lot of cash!

    • Bob

      Josh, I’m afraid a lot of people throw a lot of money away on useless insulation. Bob

  40. Alexandra

    Total newbie here, just bought a 2005 Chevy Express 1500 cargo van and need to get it ready for fall/winter as well as my final build out for the bed setup and the electrical, and step 1 is insulation. I’m already stumped! Lol.
    I’m in Northern CA, (hot summers, mild winters) and nighttime temps seldom dip below 20 degrees. But it does happen and I spend a lot of weekends up in Lake Tahoe. And frankly, I’d way m prefer to be hot than cold so I want to insulate for fall and winter. I’ve slept in my van (un-insulated) all summer no problem.
    Almost ALL of the van conversion blogs and DIY things do Reflectix directly on the metal panels of the van, as you note. So when I was at the store I grabbed that, as well as some Polyiso panels because something didn’t seem right about using just Reflectix… I guess my gut had it right. Of course I found your blog after the fact. 🙂
    So, reading between the lines and all of the comments sounds like Reflectix not a bad idea in my climate for my needs, but if I do that how does someone leave a 1/2″ air gap between the walls and the van interior metal? Just stick the Reflectix on the wall panels (plywood or the like) then mount the wall panels to the studs/van’s frame? if I did that it’d be more like 1.25″ of air gap, does that matter?
    To keep heat in, however, sounds like I should use the Polyiso at least on the ceiling, but since it goes in between the van’s “studs” (and the studs aren’t insulated) is it a waste of time?
    Or should I maybe just use the Reflectix directly on the funky bits (the awkward corners/curves/studs/wheel wells/etc) and throw some polyiso on the nice flat areas for a blended approach? Would that be too much insulation for nor cal?
    Or maybe I shouldn’t insulate at all and just frame in the walls and buy a nice big propane canister.
    Again, I don’t mind being hot but I do hate being cold.
    Thanks in advance for the advice!

    • Bob

      Reflectix directly to the walls is money flushed down the toilet–it does virtually no good. Too much air gap won’t hurt it at all and will help in the summer heat but will have very little value in the winter. The ideal thing is to return the Reflectix and get polyiso with a silver foil on one side–it will do the job of the Reflectix to keep radiant heat out, but it is also an excellent insulation, one of the best. Putting up 4×8 sheets over the ribs is ideal with the silver side toward the van walls, but in between the ribs will work as well. you do lose heat through the ribs but it’s still a huge improvement over nothing.
      The ceiling is most important, walls are also but not as important, the floor is relatively unimportant.

      • Alexandra

        Thank you very much for the quick response! Be well and happy travels

    • Bob

      Hein, I only recommend things I’ve used or know other people to have used.

    • Bob

      I’d be interested in getting a sample. But for now I’m traveling too much. Let me get an address and I’ll let you know.

  41. Connor Wehrwein

    Hello. If my one and only issue with van living is condensation buildup during the night, will putting reflectix on the inside of my van walls fix this problem? Thank you.

    • Bob

      Connor, you would be better off to put styrofoam on your walls, it is a far better insulation and will do a much better job. Give that a try.

      • Connor Wehrwein

        Thanks. Will do.

      • isabella Borriello

        Can I put the styrofoam on the wall against the metal and cover it up with carpet material?

  42. Lynn

    Hey Bob, maybe you can help me. I have Lyme a tick born illness and it has made me very reactive to any mold in my living environment. I’m needing to move out of my house and find almost all homes problematic. I’m beginning to react to many other things as well. I want to buy a step van and do a very simple living space inside. I want to have a wood stove, put in a few roof top vents and install a few solar powered vents, Ive seen on boats. I want to put down a wood floor. I would very much like to keep the walls metal if possible. What I cannot have is any moisture build up behind built in walls. I would rather have metal walls then mold growing behind them. I cannot use foam insulation..I react to it. I’m wondering if you have any ideas. The space has to be free of spray on foam,rigid foam panels..if it off gases I cannot use it. I was wanting to insulate the ceiling inside with wool covered in cloth. Something like that. Anyway I need some ideas..if ya got any. And thank you in advance

    • Bob

      Lynn, you’ve got it all figured out! I have a friend with Toxic Mold Syndrome and he can not be around any mold or any other chemicals. He bought a custom built teardrop that was all aluminum inside and that solved his problem, but your idea of a Step van is very good also. The one thing to look for is most of them put down rubber mats and mold grows under it. Be sure to lift them all up. I spent a day shopping with him looking at cargo van and every single cargo van we looked at had mold growing under the mats. That’s how he ended up in the custom-built teardrop.

      • Lynn

        I have found two step vans, both have no mats in them. I’ve only seen them in pic’s but, no mats. Does my idea for insulating the inside ceiling sound ok, with the wool and cloth, anything you would add to that? I have a love of gypsy wagons and often notice that many of them are insulated inside with what I’m assuming is wool and cloth covered. I was also thinking to install a decking roof on the top of the step van ( if I get one) I thought this would be a two fold blessing- a place to do gravity fed solar water & would help in keeping down the heat issue in the step van.
        I think a tear drop sounds nice, but then I need somewhere to go with it. I’m deeply pressed because of Lyme and not being able to work, affording camp fee’s is not possible for me. ( wish it was) I need something kinda stealth for urban camping.
        I really did not think of the mat issue in a van…of any size…so thank you for that. I have a cargo extended dodge van, a window van ( it’s dead) but I have been living in it for many months, out of the past two years. It has mat in it too. 🙁 I was thinking about a van conversion…but now that the whole floor mold thing is in my mind…I’m leaning greatly to a step van or small clean moving van…or maybe a handicap van with no mat..Those handicap vans have hightops on them..I’m 5’2 and can stand up in them. I will come back here, if and when I find the step van I hope is out there for me. Thank you so much. If you have any other ideas for the ceiling – let me know!

        • Bob

          I gotta be honest and say that I’d be very concerned about wool and cloth molding, the one thing you must not have. I recommend polyiso foam board, but you will have to research the off-gassing.
          If you are going to be in a city, either a Step Van or Box van is ideal, no trailer will work for stealth.

  43. Ken

    Fantastic info! On my new camper van, I will be putting the polyiso on the ceiling between the vans ribs. (I can’t risk losing head room by placing the board on top of them.) Should I glue the rigid board to the metal? All over? Just the edges? Adhesive suggestions?
    If you advise against adhesive, I will just install the interior wood panels in sections and press the board into place. Sure hope it doesn’t squeak!)
    The ribs appear to be attached to the van’s outer sheet metal with some form of adhesive caulk. So maybe there is a thermal break. I plan on covering the inside ribs with something like gorilla glue tape just to create a barrier. Any comments?

  44. Chris Verner

    Hi there, I am looking for some help (you may have already answered this but I am getting a lot of mixed messages from poeple) I have recently bought a Ford Transit and I am planning my conversion. I will be living and traveling around Northern NSW in Australia (relatively hot climate). I am still unsure how effective insulation will be against the heat. I have read about insulation in your post (thank you! very informative) and that most of the heat will come through the windows (I plan to have an open cabin through to the drivers seats) and no matter how good you insulate the van will still get hot. What I am worried about the most is the insulation actually keeping the heat in the cabin for longer (around bed time for example). Is it really worth insulating a van if you will be mainly effected by heat? Thanks in advance for you thoughts.

  45. Chris

    Bob, great article, thank you. I have a pickup truck with a camper shell. Wanting to take it to the snow, I’m wondering if there’s a flexible form of insulation with high r value. I’v thought of closed cell foam camping mats. The R value is around 3. Does doubling this up double my R value?
    On the ceiling, I have carpet, but I’m guessing this isn’t doing much. I could velcro the foam boards to it I guess. Usually this would only be for one or two nights. If I’m using a CAT or Wave 3 and have a fan to move the heat, should that be enough? Thanks, Chris

  46. Mark

    One more time…We own a 2016 Ford Transit 250 medium top cargo van. 1″ polyiso “dual faced boards have been purchased. Do I need single faced, with unfaced against metal wall, air space, not against metal wall? We live in Ohio and just want some insulation value for east to west trips.

  47. Mark

    Thank you in advance for any and all replies to the above post. Also, we are going to use plastic roof vents from lowes that fit in the driver/passenger windows and there are ledges to mount fans. They will fit with slight modifications to seal the open air.

  48. Maya

    Hi Bob,
    Thank you very much for all your insight and expertise. I wish I had come across your site before I purchased two rolls of R-4 Reflectix. Entirely new to configuring a van and blindly followed what the majority of people seem to be doing.
    I’ll be living out of my van for 6 months beginning in October and staying in the South to avoid colder states. My dilemma now is whether to install the Reflectix that I already bought on the walls and then add another layer of insulation, or to not bother with the Reflectix and install Polyiso by itself. Leaning towards the latter after reading most of the comments.
    Thanks again!

  49. AmieW

    Thanks for this information. I’ve been watching videos of van buildouts, and inevitably, they will put in reflectix, then put in fiberglass insulation. I just shake my head.
    I remember watching a video of someone who tore out the walls of a minivan and found out there was NO insultion in there. I’m thinking of getting a mini-van, so I don’t know what to do about that. I don’t want to tear all the walls out.

  50. JamesPortlandOR

    I’ve read through several of your posts as well as the comments. I must say, there are entirely too many YouTube videos and websites out there by people doing the most hare-brained things to their vehicles. Caveat emptor (I suppose caveat lector might be more appropriate here). This is all to say: no matter how many other sites or videos I look at, I seem to always come back to sites like yours for the bottom line. So, thank you for providing one of the few conversion reference sites that is founded in logic and steeped in experience.
    I purchased a 2015 Chevy Express passenger (extended) that I am converting for full-time dwelling with my furry friend, Brutus. I purchased the passenger model specifically so I would be able to enjoy the surroundings when parked (I hope to travel and stay in remote/scenic areas). The passenger model, however, presents some specific challenges to convert and dwell in (working around side curtain airbags, insulating windows, etc.).
    Prior to doing anything with the van, I did a rough layout (took rough measurements of the interior and created top, right and left side views in Excel). As I’ve progressed, the layout has gone through several revisions. The impetus for changes often being the recognition of what I feel I can or can’t live without. For example, the initial plan was 2 x 5 gal jerry cans for water stored inside (non pressurized water system). Instead, I purchased a 10 gal poly RV fresh water tank, had a metal shop fab a proper bracket and now have it mounted under the van (with a tank heater). Now I have space for a 2.5 gal electric water heater and water pump (I imagine a hot shower – even an outdoor one – can go a long way for morale). With each revision I’ve tried to remain conscious not only of habitability, but also weight distribution.
    I am currently in the insulation phase of my build (which is why I’m posting in the comments of this article). I expect that I will be traveling in all climates, so I am insulating the van as much as I can. I have:
    – Installed Rattle Trap sound deadening to the skin of the van (including the cab area). I didn’t completely cover the skin, but installed strips over least 25% of each surface for basic resonance control (example:
    – Over this, I added a layer of UltraTouch w/ radiant barrier (roof, sides and floor (including the cab) with the radiant barrier toward the inside of the van, of course). I purchased the UltraTouch more for sound deadening than for insulation – although the manufacturer gives an R-value from 7.85 (up) to 16.4 (down). They also identify on the spec sheet: “The fibers used to manufacture UltraTouch offer excellent sound absorption properties and every fiber used is individually treated with an EPA registered anti-microbial agent that offers excellent protection from mold, mildew, fungi, and pests as well as fire resistance.” This isn’t to say I won’t have problems, but it’s the route I took.
    – Over this I am adding polyiso. 1/2″ on the floor (under the plywood subfloor – which is supported by a wood “frame” bolted to the floor pan). At least 1/2″ on the sides and roof (will use 1″ on the roof if I can get the polyiso panels to “shape” properly – I’m hoping to do something along the lines of what I saw in a video of yours where a lady had covered her roof polyiso panels with fabric and fit them between the ribs).
    – To try and mitigate thermal loss (bridging?) at the ribs, I’m planning to cover them with a thin strip of closed cell foam (EVA foam) and then use metal tape to cover the foam. This combined with the hollow rib should give me the preferred air gap and allow for a continuous radiant barrier (the rib contact with the exterior sheet metal might negate that, but it’s worth trying and can’t be worse than nothing). I’ll then cover the ribs with “bands” of insulated fabric that will be attached with plastic trim retainers (just as the old headliner was, thus no metal penetrating the barrier).
    – In all the gaps and cubbies I am using thick loft polyester quilt batting. I did not use polyiso in the door cavities because of the difficulty of trying to fit it. Instead I used about 3 layers of (I think it’s 1″ loft) batting. It’s easy to cut. For the tighter areas, I roll it a little, use a fish tape (or wire) to pull it through long channels, etc. and then do my best to unroll/fluff it. Although I’ve not read of anyone using this as such, I imagine it operates on the same principle as any batting insulation (i.e., fiberglass) – plus, I couldn’t bring myself to use spray foam in all these spaces given this is also where I am running wiring. I will also use this to fill any gaps that remain between the polyiso and the wall sheathing.
    – I’m still in the research/experiment stage of window insulation, but leaning toward creating custom fit covers for all windows (including the cab) using Temptrol fabric (Reflectix would work, but I dislike the noise and want something that will store easy and as small as possible) as the radiant barrier side, sewn together with an insulating fabric for the other (possibly Thinsulate or SpaceLoft on the high end or ironing board cover on the low end).
    NOTE: Right now I only have polyiso on the floor, but, between that, the RattleTrap, and the Ultratouch, there has been a significant reduction in road noise. Even though I’m currently driving an empty 20′ hollow tube down the road, it’s perhaps the quietest ride I’ve ever had.
    Appreciate any thoughts or advice you might have regarding my insulation “techniques”. I can send you pictures if you would like – just let me know how to send.

  51. Jerry J. Morris

    I have a .5 x 18ft trailer with z bar walls, out skin is aluminum and inter skin is painted luan board. I wanted to put carpet half way up to stop racing bikes from scuffing the walls. I was planning on using the thinnest sheet playwood or radiant barrier treated plywood on the lower halve of the walls. I could then cover the wood with marine short pyle carpet. What to do for the roof and upper half of the walls is the concern and should I even use the plywood at all? Second part to this is I am stuck at blistering hot locations with nothing but asphalt and scorching sun, hence I race motorcycles on the tracks so it would be great to have a cold as ice trailer to retreat to after my racing. I have a portable AC with direct out duct, 6inches tube 3 inches long that connects directly to the ac. No long twisty tubes, just a 6inch galvonized tube. This works good, but wanted to be more efficent in hopes of limiting the generators running 24-7. any and all help would be appreicated. Costs are not a concern as much as “the best money can buy for this option”. I race street bikes, all italian so I am familiar with burning thousands of dollars on bikes and parts that have a shelf life of my next mistake. This should be easy as pie for you. budget is around 1 to 3k for insulating this trailer…

  52. Kayt

    My head is now hurting. There are so many differing opinions.
    I am just starting my van conversion and plan to be mostly in moderate climates with the occasional bit of cold or excessive heat. The plan is to move on when either of those are constant. Having said that, my preference is to be warm vs cold, so I will spend more time in sunnier climes.
    I was originally going to use ultratouch cotton batting as the insulation of the walls, and poly iso board on the ceiling and floor. Is that a good plan?
    Also, I’m now confused about how to deal with moisture accumulation. Should I add a vapor barrier (bubble wrap) in between the cotton and plywood wall?
    Thank you!

  53. Luis Santana

    Hey Bob, thanks for a very informative article. I thought it was great. However I have to disagree with your suggestion to not insulating in Florida. I own a black Sprinter van and when I first got it the heat was unbearable. The roof and walls would get so hot they would burn you if you touched them. Even while driving around the a.c. couldn’t cool it down. Insulating made a huge difference. I used polyfoam and reflective with an air gap on the walls and roof. I can now park in the sun and my roof mounted a.c. quickly cools the interior of the van. Even when parked out all day in the sun the heat inside the van is substantially less than it was before.

  54. acoustic insulation

    Insulation is an excellent sound absorber and can assist in reducing noise transmission through walls, ceilings and floors making the home or work environment quieter.

  55. underfloor insulation

    Another benefit of insulating your home is a reduced environmental impact. With an insulated home you will be using less energy for heating and cooling your home.

  56. Nico

    I live in Indonesia, I am more concerned about keeping heat out and waterproofing! I read this post and understood i am better off not insulating at all, bar having some handy reflectors for the windows. (FYI we are looking at a minibus conversion).
    Do you have any suggestions for us for keeping heat out and waterproofing. We are especially concerned about monsoon season and wet season, it rains everyday, torrentially in some places! Our house leaks like a faucet often, so it would be great if we didn’t have to worry about the campervan too!

  57. Michael

    Are you gluing or attaching the Polyiso or Blue/Pink against the metal wall/roof or just letting it float? Are you facing the metal foil outwards or inwards?

  58. Taylor

    Hey Bob,
    Wondering if you had any insight on insulating a slide in truck camper. The camper is aluminum sided with air in between an 1/8” plywood which is covered with wallpaper. Would you recommend the same method as your trailer insulation? It has a built in propane heater that we will use frequently to heat the camper as it will be a winter skiing rig.

  59. knauf insulation

    Lower temperatures are proven to suppress your immune system. When we go outside in the middle of the winter, we don’t head out in shorts and a t-shirt.

  60. underfloor insulation

    Insulation is an excellent sound absorber and can assist in reducing noise transmission through walls, ceilings and floors making the home or work environment quieter.

  61. Peter

    I think in a video Bob paid some company to spay insulate his van. Has anyone considered using some form of spray Aerogel?
    Spray aerogel seems to be between R6.8 and R10 or higher.

  62. underfloor insulation

    The insulation present in a filled cavity reduces this heat loss, making the house warmer or reducing the amount of fuel required to maintain a comfortable temperature.

  63. John

    Hi Bob, Thanks for helping those of us that have no clue! Have you had any”squeaking” problems with the foam sheets on the walls?

  64. Grace

    Hi Bob, Thank you for all the insulation information you have provided. I am totally lost with what to use for insulation. I am in the process of looking for a van to convert. I’ve found a few vans with some type of rubber on the floor and walls. I believe you said that mildew/mold tends to grow under the rubber, is that correct? So I should remove all the rubber in the van and do my insulation. I live in Texas but plan to travel all over the USA so the weather will vary. So will the pink/blue foam be sufficient for my insulation if I can’t afford the polyiso foam?
    Also, once I’m on the road, can I come by and meet you? How can I make that happen? I’d really like to ask you some questions since you have been living in a van for a while, but I have to many to write down. I’m 66 and single and will be driving alone with my two fur babies. Thanks Bob

  65. Kevin Duff

    This is a great post! Thanks for all the useful information! I’m just starting to research my van conversion project and I’m wondering about the following… I live in Mexico and will be in some hot places this summer. I know it is advised to not insulate but what about the following. If well insulated then would it be possible to blast the van’s built in AC from time to time? If insulated well then possibly the car would stay cool for an hour or two after using the AC? This could be done around noon, late afternoon and again near dusk to cool down the van? It sounds like AC units can’t typically be run off of solar power but would the van’s AC be an alternate option?

  66. Gee

    Hi Bob and All. Still in design and plan phase of new Ford Transit Med Hi/148″L RV (mostly) DIY reno.
    I will not live (but spend extended travel times) in this vehicle, and will lean toward warm (not snow country) climates. That said I need to insulate to both accomodate staying warm and staying cool for travel flexibility. I will not initially install an A/C (I won’t design myself out of the option however) and I will initially rely on my existing Mr. Buddy for heat. Maxx fan and T slide windows for better insulation.
    >>> That said this is my insulation plan: Please feel free to offer suggestions and amendments as you see fit; the information and variables are overwhelming at times and I’m new to this all, despite heavy research;-)
    1) Foam caulk and ‘stick and peel’ pads for sound.
    2) R-Max on ceiling ‘and’ floor between ribs (with foam fill in) foil sides out???
    3) Plywood ceiling and floor over ribs (vinyl on top of plywood on the floor).
    4) Walls with Reflectix lined plywood over ribs only (thinking no R-Max since expectations lean toward needing cooling vs. warming) Again it’s a compromise.
    Please comment and Kind Regards,

  67. Gee

    RE prior post:
    “Maxx fan and T slide windows for better ‘Ventilation'” that is:-)

  68. Karren

    Hi Bob & Everyone!
    GREAT post! Thank you!!!, for this and all of your amazing care/love for people and recognizing the need and filling it.
    I felt very attracted to your videos at first, I didn’t know why…(when I found them about a month or so ago), but all of your information was so important to me, I binged on the videos… At that time and for some years, I had been so depressed that I am 63 years old, and had 3 vacations in my working life of 48 years and since my divorce last March I was assuming I would have to have roommates, (so stressful) and work until I’m dead just to avoid being a burden on my son!
    Less than one month later I own a 2017 Savana Cargo Van with 100K mi. power train and 36K mi. bumper to bumper! I Bought it on October 23 and am hoping to be at WRTR, RTR, & I wanted to be at Jamies Van build but I am not ready… sadly might still go anyway to help. I love this community.
    To the subject at hand: Lol, I am thinking I will do polyiso with spacers of .5 in. to be sure I don’t waste it with foil side to the wall and ceiling as thick as I can afford and just styrofoam on the floor, thin.
    Did I get it right. Using reflectix on the windows. Now, I am having the top done at Fiberine with plywood mounted in the top and 2X3’s for cabinet mounting. Do I need to insulate as well. (The plywood is for strength solar and fans.)I was thinking of just painting it when done but i want to have a sound barrier as well. What is best for sound, if you know.
    Again, thank you for all you do!

  69. Rv Roof

    Thanks for sharing excellent details for van insulation. Insulating the van is less exciting process, but keeps good insulation is paramount for living a long and happy van life. I just want to add, that if you want more RV roof protection and noise reduction simply apply a coating of RV Roof Magic.

  70. RV Roof Sealants

    You did a great job insulating the camper van internally but you forgot the roof part. Reflectix insulation will not work on roof and for that reason I would recommend applying RV Roof Magic. RV Roof Magic will not only act as insulator but it will also protect your van from leaks and seepage.

  71. Sophie Turner

    These are some great tips! And you’ve got it right; it makes a massive difference. Choosing the right technic can be pretty tricky, but this guide made it a lot simpler! Thank you so much for writing; this was helpful!

Table of Contents