[Greenbuilding] Cathedral Ceiling & Icynene Insulation

[Ken Beiser]

We are in Montana and this is certainly ice dam country.  I use foam insulated roof systems on most of my projects.  Some are SIPS and some are either built up or spray urethane.  I have done quite a few designed as "warm roofs"  (un-vented and no space between sheathing and insulation) with no adverse effects for more than 15 years now.  A lot of roofs are metal but some roof coverings were three tab asphalt/fiberglas shingles and I always recommend a good quality architectural grade shingles with a 50 year warranty.  On one project we had to switch brands (to Iko?) so the warranty would not be void.  

The only areas I have ever seen ice dams on my roofs are when against my recommendations, they put in roof windows or skylights.  Another area that has shown some ice damming is in some valleys.  I think we need to be extra careful insulating and sealing valleys.  

I would have your inspector review the information from the SIP association on roof coverings.

Be careful up there.  A friend of mine died on Friday in a work related incident.  We are just devastated by it...

Ken
Whitefish, MT