What is the process like, or how easy is it? I'm referring to the process of adding roxul/polyiso/xpe/eps to the outside of new construction. I'm curious how you fasten the boards with the furring strips - do you do a small piece at a time, or do you try to get three boards up and apply a furring strip to all three at once? Thanks!

It's pretty easy; tack up the insulation with long roofing nails or nails/screws with large washers. Does not take very many as you're only holding it up until the strapping is screwed on. Be sure to mark out your studs so you know where to find them after the insulation is up! Have't used Roxul but it's "softer" than the foams so you'll need to use care when setting the screw so all the strapping is on the same plane.

Ah, ok. No concern with small holes? Or do you typically tack where a screw will eventually go? Or do you just leave the nails in?

As for insulation, not sure. I'm leaning towards one layer of 1.5" polyiso, the remainder being XPS or roxul, though I heard some good things about EPS type II that I need to read about still. I'm in a cold climate (USDA Zone 5).

Thanks!

John

don't obsess about the small holes, but do tape the outside of the foam with a long lasting tape like 3M 8067 or SIGA. If you go with Roxul, you'll need to air seal the wall under the Roxul. Polyiso gives you the best R/$. look for it at a commercial roofing wholesaler; they have much better pricing than lumber yards or box stores.

If you order it from a commercial roofing supply, specify aluminum foil face; otherwise you might get the asphalt paper face which the roofers like, but is hard to tape.

I'm not sure about using all polyiso - from what I've read its performance degrades in cold weather. I'm contemplating a sandwich of multiple insulation products, with poly being closest to the wall, then one other product. I'll create another post to discuss the insulation I'm planning.

Thanks!

I used 1.5" Roxul Comfortboard attached with 7/16 x 1.75" crown staples. Using a pneumatic stapler made it go quick and the length worked perfect to hold well without blowing through the 1/2" osb sheathing. Most people put the wrb under the Roxul board but I am also doing an open joint cladding system so I put Vaproshield's Revealshield IT over the insulation. To attach the Revealshield I used 6d x 2" plastic cap nails. This also worked really well, I was worried about getting furring strips on right away but its not a problem the membrane is plenty secure with cap nails, integrated tape, and wrb sealant. Furring strips are pre-painted 1x3 pww attached with #10 x 3.5" screws. Getting a flat plane over the Roxul is not too difficult. I use a level or straight edge to check as I go and adjust screws as needed, not a significant amount of extra work pretty simple.