Probably used the wrong insulation.

[Kornbread]

I built my floor and coated it with roof tar. Then I pressed pieces of foil backed Styrofoam insulation into the wet tar. I started to doubt my choice of Insulation when I tried to cut the stuff. But, it was late in the day and I wanted to get the floor done so it would have plenty of time to dry before I tried to install it on the trailer.

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I came home this evening and checked on the drying process. The foam feels like it's firmly adhered to the tar. I planed on adding some screws and washers to help hold the insulation in place. However, I noticed that the foil on the back of the Insulation is already pealing at the corners and edges.

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I can imagine that when I'm driving at highway speeds this foil is going to start to peel and it'll look like I've run over a weather balloon.

I'm thinking of picking up another sheet or two of some solid foam insulation and adding another layer over the foil. However I'm not sure about the thickness. I'm not crazy about having the foam stick out past the wood on the bottom as that would interfere with mounting the wood floor onto the trailer.

Also I'm not sure what would be the best way to attach it over the existing foil backed insulation.

Any Ideas?

[DMcCam]

Hi Kornbread, I used Styrofoam insulation with the foil on my build too. I peeled the foil off because I couldn't think of a way to keep it in place. It peels very easily so I thought it would release inside my walls and ceiling not keeping the structural panel solid. It probably doesn't give much of a boost to the overall R value anyway. To glue my two layers of insulation together I used the 3M foam adhesive from Home Depot and a grooved trowel.

All the best,

Dave

[Kornbread]

...To glue my two layers of insulation together I used the 3M foam adhesive from Home Depot and a grooved trowel.

All the best,

Dave

So you used two layers of the Styrofoam without the foil? How's that holding up? I'm asking because as I cut it (with a brand new razor) the little white pebbles are all over the place. So I wonder how they hold up in the wind at hwy speeds? Also, I assume you used some screws and washers in addition to the glue?

[les45]

I would cover the entire bottom area with a sheet of luan or 1/4 ply and then seal the heck out of it with your asphalt sealer. Nothing you do with the foil exposed will keep it from coming apart over time.
It looks like you have room to add more insulation and stay within the width of your framing. If you do, you might want to consider adding more insulation, preferably the rigid board type, to fill the void.

[DMcCam]

Hi Kornbread, My Insulation is sandwiched between 2 layers of 1/8" Baltic birch plywood in my walls and ceiling but not the deck. When you glue all of it together it makes a very strong structural panel. I used the 3M foam glue between the layers of insulation then Titebond 2 covering the whole thing under the 1/8". So far so good (I'm still building her).

It looks like you are building for cool weather camping? If so, then it makes sense to cover the insulation. For your deck I'm with Les, you might what to encapsulate it with 1/8" plywood or something. There are several members' trailers without anything over their insulation beneath their decks. As long as it has been seriously glued in place it seems to hold up pretty well, as long as you're not boon-docking that is.

All the best,

Dave

[bobnlyd]

dave...are your walls 1/8" ply with framing 1 1/2" sq studs in between also...what skin did you use outside

[jeff0520]

Hey, I used the same insulation. I just painted a second coat of tar on top of it to seal it in. Seems ok so far. We'll see how it does on the road

[DMcCam]

Hi Kornbread, I mostly followed Steve Fredrick's shop manual for construction in which you build from the inside out. You can find it http://www.campingclassics.com/ Once my deck was in place I glued the interior 1/8" Baltic birch ply to the 3/4" then added the insulation. My walls are skeletonized 3/4" 'signboard' with the voids filled with Styrofoam insulation. With both layers of birch plywood the walls end up 1" thick. When all the interior cabinetry was built, I stood the walls. Then added the headliner then the spars and blocking. Once that was done, we insulated the roof between the spars and the headliner then added all the wiring. I'd drill your wiring holes before you glue the ply to the walls and install the spars; it's easier trust me. When we had all the wiring in and set, I skinned the exterior with my second outer layer of 1/8" ply. The whole structure becomes a very solid yet pretty light unit.

Cheers,

Dave

[Kornbread]

I picked up a second sheet of insulation to go over the foil backed stuff. This time I got the solid blue Styrofoam. I pealed the loose pieces of foil. if it wasn't loose I left it alone. I used some spray adhesive between the layers. The I ran some screws with washers through the foam and into the plywood floor.

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One sheet wasn't enough to cover the entire bottom so I doubled up on the foil insulation underneath the galley section. I don't guess that needs to be insulated anyway.

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[bc toys]

all you need now is some plywood on top and you are ready for the walls you moving right along.