Chinook RV

Has anybody put spray foam insulation on the outside of their actual bathroom walls (not the coach walls)? We'd previously stuffed a lot of insulation in the space between the coach and bathroom walls and definitely noticed a temperature difference. Unfortunately, we later ended up removing all the insulation after having to clean up the resultant mess from a mouse invasion. Now we've finally decided to try again and are considering foam, just in case (God forbid) we ever have another mouse issue.

I'd appreciate any thoughts, pro or con.
Thanks.

Well, it depends on the foam type. I would assume you are considering the common building insulation material Spray Polyurethane Foam (SPF).

This certainly has good insulation and void filling properties BUT there are health concerns, both during application and after curing (drying). Nasty chemicals you may become exposed to include isocyanates, benzene and formaldehyde, depending on the formulation.

The manufacturers have the usual warnings like “for professional use only, avoid vapor, mist, etc….” and recommend protective gear when applying. After that they claim the material is safe. However persons who have allergies or asthma problems may well claim otherwise.

There’s more here from the industry leader BASF:
http://www.spf.basf.com/material_safety.php

Otherwise, I'm sure our boat friends will chime in with more practical experience. B~G, I'm thinking of you

Cheers, Ted

Thanks for your reply, Ted. Food for thought, for sure.
Since there's already some spray foam on our Concourse walls, we thought it might be ok to add more. Still haven't decided which way to go.
What else, if anything, have others put behind the bathroom walls for insulation?

I'm sure you could wedge some foam board in there, but if it's not secured it can get awfully squeaky going down the road.

Considered that but I think the squeak would make me crazy(er). I couldn't even stand to hear the wall clock ticking!

I tried rigid styrofoam board in there once but it breaks and crumbles easily. Also squeaks, as noted. Another option is fiberglass home attic insulation. It is inert and soundproof but be sure to wear gloves as the fibers can irritate the skin. Last time I looked Ace hardware had this in rolls or panels with various thicknesses.

I hate to work with fiberglass insulation, but it is probably one of the best option since it does not break down like the spray foam or styrofoam, and squeaks. It also is pretty forgiving to variation in thickness, so you don't have to be very strict about how thick should you get.

I haven't installed it yet, but I purchased 3M Thinsulate automotive insulation for that area. I may try to pull it up into the cavity via the bathroom skylight hole (or if that plan doesn't survive reality, I'll figure out another way). I bought it from Hein at Impact Products. I think it was something like Thinsulate 600 SL, but don't quote me on that (is something like 1-1.5" thick, IIRC).

Thinsulate is apparently used in a lot of vehicles now. It comes in a roll something like a fiberglass batt, with scrim on one side. Does a combo of R-value and sound insulation (I'm mostly interested in R-value).

I think one of the newer Thinsulate type products is the easiest way to go for the curved walls. Costs more but probably worth it. There really isn’t that much foam on the walls of the chinook, and it’s not applied all that uniformly. I’m also looking at thinner foams for the floor, with a thin layer of plywood on top.

I'll check out some of the Thinsulate products. We previously had fiberglass insulation in that area. It was pretty easy to stuff it into the cavity and as I said, it did make a good bit of difference in temp. However - it was a mess to clean up after mice got in and decided they were fans of living in a Chinook.