I love insulation! The wall composition of this house is the aspect that I am most excited about. Windows are nice, radiant heating is cool, hardwood floors lovely, but INSULATION is tops with me. (see “Anatomy of a Double Wall” for details on our wall system).
I’ve spent the last four weekends insulating. It took two weekends to install roxul in the outer 2×4 wall (R14), and two more to install the 4×8 sheets of 5.5″ EPS foam (R21) between the two walls. Each of these sheets has been joined together or caulked with expanding spray foam, creating what I hope will be a very tight wall (aiming for 0.5 exchanges per hour ACH @ 50kp).
I still have a little bit of work to complete around the window headers. For this task, I will be using 4″ EXP boards (R20) in order to ‘boost’ the insulation in the constrained space (less space because the ‘header’ is a beam made from double 2x12s – so there is no space within the header to place insulation). I love using foam here because it enables me to eliminate all thermal bridging. Combined with the R4 sheathing board on the outside and the insulative value of the wood (when sealed within the wall effectively) and even the headers – traditionally a weak area with respect to insulation – will be R35 or greater.
When complete, the inside 2×4 will be stuffed with dense-packed cellulose too. (nominal R55 wall):
By the way, all of this foam is used and sourced locally. As such, it is 100% recycled and local (kind of). This is very useful if you are seeking LEED certification (we are not).
If you are planning a superinsulated house build, it is worth your effort to keep an eye out for used foam through kijiji or craiglist, etc. Or, contact Chuck Cobeil from “Clean Fuels Pipeline and Conservation Products” in Westport, Ontario. Chuck has been buying and re-selling foam insulation for a couple of years – he has a warehouse full of the stuff . If you don’t like the idea of used materials, Chuck has plenty of seconds (typically with printing flaws or rounded edges) and new materials too. I have bought a bunch of material from Chuck and his prices are about 40% of retail. He can be reached at 613-561-6780.