Spray Foam

[jerrypike]

I'm completely removing the interior skin on my 31 footer
to find and fix water leaks, plus wiring updates
I'm considering spray foam insulation in place of fiberglass, but am not sure how it will perform

cant find any discussion about this

thanks in advance

[slowmover]

There is more than one long thread on insulation comparisons.

The drawback is if one ever needs to replace a panel or two. For starters.

Avion and Streamline both used spray-in.

[GeocamperAS]

Originally Posted by jerrypike

I'm completely removing the interior skin on my 31 footer
to find and fix water leaks, plus wiring updates
I'm considering spray foam insulation in place of fiberglass, but am not sure how it will perform

cant find any discussion about this

thanks in advance

There is a thread out there somewhere. If my memory has not failed, the consensus was: the SOB's that take two pieces of aluminum in a wood frame and inject foam into it. The foam then adheres to both pieces. What you are thinking will only adhere to the outer skin. (here is where the thoughts went) Adhering to only one side, with all the bouncing and vibrating down the road will in time cause it to break apart.

[kb0zke]

Newell uses it. They have a totally different suspension, are are several times as heavy, so that may make a difference. I've not heard of them having any problems. They actually spray three layers, so maybe that makes a difference. I suspect that there is more involved than just getting a can of foam at Wal-mart and spraying away. There is probably some prep on the inside of the exterior wall, and perhaps some sort of adhesive on the outside of the interior wall that helps the insulation stick to both walls. An organic chemist could probably answer in more detail.

[slowmover]

The stuff is an option. It is in repairs down the line that makes it a burden to remove. Any leaks from the shell may therefore be compounded.

[AWCHIEF]

Unless you are experienced using spray foam expansion can be unpredictable and potentially damaging. I use it in flotation chambers in the boats that I build.

[NJtoNC]

I have considered using tiger foam. However I feel the R-value is comparable to prodex. The closed cell spray foam would add rigidity and won't soak in moisture. Could help seal seams, perhaps. I put very little weight on those who claim the spray foam will shake to bits. Avion used it and I have seen it still stuck on the walls of a avion in a junk yard that,had a fire,in part of the trailer. It was an early model - pre 63 I believe.

[scamp]

I think it would be a improvement make the shell more rigid it wouldn't absorb water ,and if got wet it would still have aprox same R value but like some have said would be a challenge to replace outside panels or work on wiring unless the wires are ran in pvc tubing, it would also provide more support to the aluminum skin in hail storms and maybe lower the damage.

Don

[blkmagikca]

If you use spray foam and ever have to do any repair that requires you to have access to the inner side of the outer skin or wiring between the inner & outer panels, you will have a lot more work on your hands. Back in the '90s I rebuilt an SOB and used Roxul Plus. Roxul+ is a "mineral wool" and handles like fiberglass without the skin irritation and the R-factor is good.

[IanRae]

As a building performance contractor (lots of retrofits on existing houses) we use spray foam and other insulation materials regularly.

There's two types of spray foam that we regularly use: "1-part" (the kind that comes in a can from the lumberyard) and "2-part" (which comes in two separate tanks and is mixed during spraying.)

Tiger foam, etc. is 2-part. Great Stuff, etc is one part. One part foam is ok at sealing cracks, but doesn't stick as well. My hunch is that, in a trailer, either kind of foam is less likely to disintegrate than to just come loose from the surface it's sprayed on.

With either type of foam, you need to be very careful applying it to eclosed spaces, as the expansion can destroy stuff as it cures (even minutes or hours after it's applied!)

In my trailer, I'll probably use a combination of sheets of foam cut close to fit, and then fill in gaps with one part foam. You can also have two part foam professionally installed for a similar cost to just buying tiger foam kits (mostly due to them purchasing in bulk.)

Roxul is also a good option, but you will get the highest R value out of foam.

One other trick - you can apply something like plastic or wax paper to places you don't want the foam to stick to.

Good luck!