I understand some of these expanding foams have been reformulated to reduce the volume of expansion compared to the first formulations that were marketed a few years ago. One real life account I know of was a fellow who decided to eliminate the drafts around the double hung windows in his house, so he shot Great Stuff into the void area between the jambs and the framing of the rough opening for the window. The great stuff expanded so greatly that it bowed the jambs in tight against the sashes, and as a result his "double hungs" became "fixed panes." And it's one of those decisions that is fairly unforgiving, if not irreversible, in nature. Once you've done it, you will either live with the result or expend a lot of effort to undo it. Robert / Susan Harper wrote: > >I'm planning to insulate my trailer using this > >kind of stuff too ..... My concern with this process > >would be to fill up the wall cavity without bulging out the panels. > > > >I had figured on applying to the open wall, trimming it flush and then > >installing the interior panels. I suppose applying a plastic liner first > >would to the trick? > > > >Jay Griffin > > Before anyone gets carried away with Great Stuff foam or any other expanding > foam and blows out their Bubble, let me clarify that my intention for this > product is to fill and seal the gaps between the plywood floor edge and the > belly pan, from the bottom. I would NEVER consider filling the walls of an > Airstream with this stuff. It expands a LOT, and it will DEFINITELY put > bulges in wall cavities if used there. I am really using it more as a caulk > to get into places not easily reached. I'm sticking with the fiberglass > batting in walls. > Jay, if you've got access to the entire panel (open), why don't you cut > solid foam sheeting to fit? I personally would not, because I think you'll > find that a double skin of aluminum with something fairly rigid inside (even > expanded foam) will not be nearly as forgiving about being bumped and poked > and banged. It will not "give" as easily from the outside. It will dent more > easily having lost it's ability to flex into the cavity behind it. Be > careful. You might consider a combo of thin foam sheet and fiberglass bats > to bump up your R values ... maybe. Another blanket might be easier. > > Bob Harper > '62 Globetrotter in SC
