Belly Pan ideas for '48 Boles Aero

[bgordon]

I'd like to put some insulation on the underside of my trailer (pic attached). The frame is made of 1.5" angle iron with some 3" structural channel as the main rails. This would be mainly to extend the comfort range of the trailer. On that note, I have a few questions:

How beneficial is 1.5" of insulation going to be? I assume not much, but would be noticeably better than the bare subfloor. I have a tongue and groove flooring on top of it. No vapor barrier or anything else.

I have looked into putting skirting on the trailer. Would it be wiser to do this first?

--
My thoughts on the design

1.5" solid foam insulation seems like the obvious insulation to go with. Those can be cut to the shape of the frame quite easily and should install well.

I am less sure about how I would setup the skin or belly pan. It seems like aluminum or ABS plastic would be a good covering.

An initial thought is that the skin could mount to the foam and be installed in pieces. Two concerns there are that the skin could delaminate from the foam and that the gaps between the panels would negate the insulation.

I'm hesitant to build a belly pan that is sealed. It seems best to have something that could drain. Although I have no plumbing right now and plan to keep it as such - I just use a refillable water jug. There is no shower or toilet so there wouldn't be the worry about a pipe busting or a leaking shower.

Any thoughts on how tightly sealed the pan should be and wether it's worth it are welcome. I am comfortable in the trailer without it down into the low 30s. I would like this to do some skiing out of it this year so that means teens or lower.

[HiHoAgRV]

I used 3/4' foam spacers and a 3/4" sheet with all edges sealed by tape.

http://www.airforums.com/forums/f109...tml#post998462

[FC7039]

You could spray it with foam insulation then spray the foam insulation with truck bed liner and forgo a belly pan

[bgordon]

The trailer is a work in progress, so I don't want something that would be too much trouble if I had to go back in there.

Would 3/4" foam with 3/4" spacers be better than 1.5" foam? It seems that would be dependent on sealing all the seams as well.

The trick is how to mount a protective material. It seems like even with truck bed liner a chunk of foam could get knocked out. I take the trailer on dirt roads.

I've attached a quick cross section sketch of the frame. The angle iron doesn't leave a face to connect anything to so I maybe looking at tacking on a bunch of tabs.

If I were to do foam with a sheet of aluminum on top, how tightly should I try to seal it?

[HiHoAgRV]

I used 3/4" foam because it was the best available locally. The 3/4" airgap will have an insulating value as longs as the edges are taped to minimize airflow.

Your frame sketch look similar to my '63, here is how I assembled it all.

[robwok]

You may want to be careful about water being trapped between the wood floor and the polystyrene. For such a small area, you could consider the radiant bubble wrap type product.

The belly pans seem to be a place to collect water in the airstreams. it drains into the belly pan, and then drains out from there. Whatever you do, just keep from creating a wicking to that pan - i.e. don't fill the space with fiberglass.

[bgordon]

I used radiant barrier on the walls and ceiling and it is working well. Keeping the heat down when the sun hits this tiny aluminum box in the summer is important. The resistance to moisture is a bonus.

It doesn't seem like the radiant barrier would be as effective under the floor. The plywood subfloor has two coats of waterproofing on it. It seems like coating with an undercoating or truck bed liner would've been a good idea prior to install.

[ventport]

I would go with the spray foam and bed liner if it was mine. Great R value and it really seals it up.