Today's big job was: insulation. SPRAY FOAM. Yep, we did that.
I thought and thought about how much of a PITA it was going to be trying to jam foam sheets or reflectix in the hard to get to spaces around the trailer, and decided that it was worth investigating some of the actual properties of spray foam. I did a couple of experiments with latex foam and discovered that this what I would call "cautious" formulation would not pose a problem at all inre fears of the foam blowing the hulls apart with the force of its expansion. When I sprayed it into a little cardboard box that some Allegra allergy meds had been packaged in, nothing exploded. I thought if the foam wasn't going to wreck a weakly pasted paper box, it wasn't going to wreck a trailer.
I started by taping a 20-ish length of vinyl hose to the spray foam nozzle to extend the reach, and set about trying to fill the considerable volume of the hollow door. After dumping 3 cans into the door and seeing that it barely filled the bottom, I decided that the latex foam was just not going to cut it. So we switched to Great Stuff foam in the window & door version, blue can. This is the kind that cures soft and flexible, not super hard and powdery, but has better expansion properties than the latex type foam.
Anyway, it did the trick. We actually found that shortening the vinyl hose extender to about 10 inches gave us more control over where the foam was going. In order to direct the foam into the many hard to reach places between the Burro
hulls that were not easily accessible from the open areas under the seating cubbyholes and from behind the kitchenette, we drilled several very ugly holes into the inner wall, mainly along the ceiling and front corners. Well, we'll patch those up, no big deal, including the one that accidentally went all the way through to the outside (oops).
The reason we are doing this job now, before painting
, is that I realized while the camper is still mostly white (except for the areas that have been Bondo'ed and primered) we could use a strong shop light
to shine against the outside hull to illuminate the empty air pockets, taking advantage of the slightly transluscent nature of the glass and gelcoat. My theory was that the foam would obscure the light
from the inside as the foam covered the space. And sure enough that worked as a strategy for making sure we were getting decent coverage.
And here is the key thing about this spray foam: as long as it has a place to go, it will get out of its own way. In this window & door flexible-cure formula, there's just not enough force in the foam expansion to affect the fiberglass trailer walls. Now, if I were spraying it into a space where there was no exit and exceeded available volume, that could potentially be a problem, especially with a harder-curing foam. But in a Burro
- and probably also in Uhaul
and similar trailers - there are no sealed off spaces in the air space between the hulls.
What the foam does is travel around to fill the available space, and when that runs out it squelches in a very messy, ugly way from the nearest opening. That could be the hole I was spraying into, or some other gap. So the inside of my trailer now looks like it has been in a neon colored horror film, but that will all sand off.
One more note: if you try this at home, I have a couple of recommendations because it's about the messiest job ever. I trashed a hat and my otherwise useful cotton-duck coveralls because of the excess foam that was goobering out all over the place. So if I did this again I'd wear those tyvek painting
coveralls and a hat I didn't want any more. Uh, I put the hat on AFTER a couple of gobs of foam dripped into my hair from ceiling holes....Great Stuff, not great in your hair, actually. Also, very sturdy protective gloves are useful for this stuff, too.
Well, some photos of the carnage.