Floor Insulation

[Venom]

Hello. Been browsing for quite awhile, finally joined the conversation. Just starting my 1st build and have a question about floor insulation. I see most everyone sandwiching the insulation between 2 pcs of ply for the floor. However, has anyone skinned the bottom, filled the frame with insulation and just used one sheet of ply on top? My purpose is to utilize every inch of space possible, lighten the load just a bit and reduce the height just slightly. Pro's/con's? Your thoughts are welcome. Thanks

[Shadow Catcher]

Our floor insulation is a 5" foam mattress, works well.

[KCStudly]

People have skinned under like you are suggesting. Others have put ply directly on the trailer frame and fit insulation up under the trailer with no bottom skin, or a lesser plastic skin (not structural). One build I recall just used long drywall screws and fender washers placed along the edges and seams holding the insulation up.

It all depends on what climate you live in and think you will be camping in. Some feel that the mattress is enough insulation (like SC ^), while others have concerns about condensation building up under the mattress. Supposedly having dedicated insulation in the floor helps reduce that tendency.

[tony.latham]

Hello. Been browsing for quite awhile, finally joined the conversation. Just starting my 1st build and have a question about floor insulation. I see most everyone sandwiching the insulation between 2 pcs of ply for the floor. However, has anyone skinned the bottom, filled the frame with insulation and just used one sheet of ply on top? My purpose is to utilize every inch of space possible, lighten the load just a bit and reduce the height just slightly. Pro's/con's? Your thoughts are welcome. Thanks

I'm in the camp that if you need floor insulation in a teardrop, your mattress is too thin.

I'd argue for a foam-core floor if you are thin-skinning a boxed construction floor and need to add support and keep the weight down.

Tony

[Venom]

Good to get some advice from experienced folks. I do plan on doing some camping in less than favorable conditions, so I think skinning the bottom and filling the frame with insulation is my best option. I don't like the idea of leaving the foam exposed on the underside. This is going to be used offroad at times, so mud and muck will ruin any exposed foam. Thanks again to all of you.

[kokomoto]

Hello. Been browsing for quite awhile, finally joined the conversation. Just starting my 1st build and have a question about floor insulation. I see most everyone sandwiching the insulation between 2 pcs of ply for the floor. However, has anyone skinned the bottom, filled the frame with insulation and just used one sheet of ply on top? My purpose is to utilize every inch of space possible, lighten the load just a bit and reduce the height just slightly. Pro's/con's? Your thoughts are welcome. Thanks

I am one who elected to sandwich my floor with insulation. I wasn't worried about the cold floor with a nice foam mattress, but I was concerned about condensation forming under the mattress. Although that may just be a conspiracy theory, or very dependent on climate and region of the country. In the end, I decided that it was better to have and not need than to need and not have.

1x4 sandwich frame and foam insulation between two sheets of 1/4" plywood (which is actually 3/16" thick). It seemed like a good compromise, and I saw not much downside to doing it other than it takes a little time to assemble the whole thing. I probably could be just as happy with a solid plywood floor, but I'm pleased with how my floor turned out. If you enjoy building stuff and gluing it together, then I would consider it, but recognize that it may not be providing you with a lot of benefit.

[KCStudly]

Well said Kokomto, ^this parallels my thoughts nicely.

The thing that concerns me about skinning under the trailer frame and filling in between xmbrs, etc., is all of the places around the suspension and whatnot where water has a potential place to get in. The advantage of building the floor off of the trailer and bolting it down on top is that it is a lot easier to seal a contiguous flat surface and just seal around the bolt holes, than it would be to fit and seal around irregularities. Not saying that it can't be done well, just saying that it may require some extra effort to get it done that way and have it last.

We all seem to go to some extra effort on some aspects of our builds that are important to us. Pick your battles and keep your eyes wide open so you know what you are getting into. (I've been down the rabbit hole many times!)

Maybe it is a moot point. Many people report that they don't ever see a problem under their trailers, that there is surprisingly little activity under there; some don't even do much treatment at all (maybe they live in dry climates and stick to paved roads?). OTOH, people like GPW, in sweaty NOLA, have trouble with rot just from sitting in the driveway (tho drip edges and resealing edges thoroughly seemed to have helped fix it).

[Atomic77]

Let me offer my two cents...

First, I am by no means an expert on building campers. My background is in building construction, hotrods and race boats. I did a lot of research as well prior to starting my build. I kept seeing builds with a double floor and insulation sandwiched between. To me, and this is just an opinion, I think it's overkill. With that said, I do think insulating the floor is important, just not to that extreme. A double floor is added weight and materials that I believe to be unnecessary. Are you camping in the winter frequently? Because that's about the only time I think it would do any good. Heat rises. I think insulation in the walls and ceiling are far more crucial. Of course, moisture is a concern and it needs to be insulated for a barrier and to stop possible drafts. If you get a chance, stop by my build and explore how I did our floor. It's simple. It's inexpensive. It adds little weight. I've also spent two very comfortable nights in it in below freezing temps with a small ceramic heater and all is well and good. Good luck!

[QueticoBill]

Michael - I looked at your build thread and I didn't see where the foil wrapped celotex was. Under the 5/8" ply? Adhered with epoxy? Between frame or continuous over frame?

Thanks!

[Nobody]

Whan I built my TD in 2006 I seriously debated (with myself) the insulation ??. I wanted a quiet, warm/cool unit that I could camp in anywhere (much of our camping has been in national forests, ofttimes dispersed camping where there is no organized campground). We have towed our TD with a 4X4 pickup since new & frequently had to use the 4WD to access the areas we wanted to camp. I built my floor frame from ripped 2X4s with a 1X6 faschia board on either side. My floor is 1/2" CDX plywood, with 1" foam board insulation in the 'voids' created by the framework. I cut the foamboard & placed it in the voids after coating the underside with asphalt fence post protective emulsion. I placed the foamboard while the emulsion was still sticky, then used scrap 1/2" square boards from my build as 'battens', stapled in place to hold the foamboard in case the sticky stuff didn't hold securely.






We've towed it nearly 30K miles in 10yrs, over almost every kind of road/terrain. The exposed foamboard still looks nearly new under the trailer, with a few 'scars' from rocks/pebbles thrown up by the wheels/tires in particularly rough toads/trails.




The sides were built with stick framing (3/4"X1-4", inner walls 1/4" oak ply & outer 1/8" luan ply, with 3/4" foamboard insulation) & the roof/front again ripped 2X4s which gave me 1 1/2" voids to fill with foamboard insulation on the roof & front of the TD. Roof & front outer layer is 2 layers of 1/8" luan under the aluminum skin. We sleep on a 4" memory foam mattress from WalMart with a 1 1/2" memory foam 'egg crate' topper, giving us 5 1/2" which is plenty of support since we're not large folks. We've found over the years that while the insulation is welcome for temp control in extra warm or cold weather, we're most grateful for the effect it has on external noise. It works great for sound deadening effects in noisy campgrounds if we want to sleep while other campers are 'celebrating' something... We're very happy that I added the insulation. It was relatively inexpensive & easy to do while building.

[Venom]

Appreciate everyone's input here. A little more info on this. I do plan on using my teardrop during colder weather here and there, but not very often. I want some insulation under me just in case. Foam doesn't weigh much and the space in the frame is wasted anyway. My trailer is a HF bolt together, however, I have removed all the bolts and welded everything. So, skinning the bottom wont be difficult. As far as water/mud intrusion, after skinning the bottom ill be sealing it with some rhino liner or something similar. I apologize for leaving that info out of my original post. Thanks.

[Padilen]

I insulated my CTC with rigid foam between the frame members. I used 1" for spacers the 2" cut tight and caulked around seams. I then painted it with UGL waterproof paint. I travel on dirt roads and my underside is clean. I'm planing on another layer to go over my frame members and repaint. This insulation is for a clean look and sound deadening. Pest and OCD control.


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[Atomic77]

Michael - I looked at your build thread and I didn't see where the foil wrapped celotex was. Under the 5/8" ply? Adhered with epoxy? Between frame or continuous over frame?

Thanks!

It's on the first page of the build journal, last post on the page. The 1/2" Celotex was bonded with epoxy to the 5/8" ply then sandwiched between the frame and the ply. It's very simple and effective. Once installed I also coated the underneath with heavy bed liner. It looks very clean and nice. Also, the bedliner is thick so it really sealed everything up. Like I said, I've spent two nights in it, in sub-zero temps. I had a small, ceramic heater that kicked on in about 20 minute intervals and ran about 7-8 minutes at a time. I walked around in my socks and the floor warmed up nicely. I didn't see any signs of moisture and everything stayed warm and dry. I'm pretty pleased. Clean, simple and light.