I took a peek inside a small wall panel and found dirty fiberglass insulation. The cavity appears to be about 2-3/4 inches deep, so that’s plenty of space to replace with a modern line of foam insulation board like this:
Owens Corning FOAMULAR comes in various thicknesses: 1/2″, 3/4″, 1″, 1-1/2″, 2″ and 3″. The R-value ranges accordingly from R3 to R15. By comparison, a typical 4-inch wall cavity in your home is insulated with R-15 fiberglass, which implies that foam board is 25% more effective and probably easier to apply to square surfaces. For 4’x8′ sheets at Home Depot, the cost ranges from $19 to $29 for each 32 square feet. And that means even with waste, this step will afford good bang for the buck.
I went to Home Depot today and found a different brand that is made of styrofoam and includes a thick layer of aluminum foil. Not sure which would be better now, but a reflective thermal barrier seems like an upgrade.
For the Scenario Mobile, it’s as much about acoustics as thermal comfort. So the walls will probably get 2-inch foam while the floor and ceiling might only get 1/2 inch. That’s to maximize headroom. As-is, I only have 6’1″ of clearance from floor to ceiling. But the ceiling appears to also have a 2-3/4 inch cavity, which gives me some hope that I can do this without losing any height. My son is 6’1″ and it’s going to be awkward if he has to hunch over. If I can reduce the ceiling cavity to one inch or so (even in pockets), that’s a major win because i can put in a new hardwood subfloor.
So I’m thinking the process will go something like this:
- Pop all the rivet heads with a hammer and chisel and remove all the aluminum interior panels. I’ll number them in case I want to reuse them later.
- Clean out the old insulation and dispose of it properly.
- Clean out the bare frame rib cavities.
- Figure out my finished wall depth and measure out all the frame ribs to sanity-check my Window Plan.
- Patch all holes with aluminum tape. Even a small hole under the floor can allow water to spray in while driving.
- Apply a vapor barrier to the whole thing. I need to research options there.
- Figure out where to run electrical conduit so that I can snake wires easily.
- Cut and adhere the foam insulation boards with construction adhesive.
- Join all the seams with aluminum tape.
And hopefully, that will create an airtight and watertight box ready for cladding. I’m imagining black-and-white checkerboard vinyl on the floor, loop pile carpet on the walls for sound absorption, and quilted aluminum on the ceiling for that retro diner motif.
What did I miss? Oh, yeah, the ceiling. We’ll need low-profile LED lights, skylight vents and an air conditioning unit. More on that later…