Q&A: A Forum for Green Building Experts and Beginners

I live in a heating dominated climate with many cloudy days. Taking all window buying considerations into play I have found the replacement window decision making process tricky. I seem to have found a pretty good window sold through the local lumber yard here in Missoula MT. It is a PLYGEM vinyl triple pane marketed as R5 glass. The marketing is slick but the real values as rated by the NFRC back it up. Or seem to. Does anyone have feedback about this plygem product?

Mr. Holladay once wrote of rafters, "Yes, you can combine rigid foam and spray foam if you want to save some money. I would be inclined to install the layers of rigid foam first [I, Gordon, assume this means the rigid foam would go against the roof decking] -- cut undersized, and with canned foam sealing the perimeter of each rectangle -- and cap everything with spray foam [I'm seeing this as under the rigid foam and further away from the roof] from a contractor's truck."

I am an architect in Atlanta, GA (climate zone 3) mostly designing modern/contemporary homes that typically have flat roofs. There seems to be a lot of conflicting information and opinions out there as to the best way to insulate these types of roofs. Typical construction would be 12" deep ceiling/roof I-joists or 2x4 open-web trusses with flat OSB decking above. The most common potential options (all unvented scenarios)are:

Zone 4 marine. I'm pondering insulation strategies for cathedral ceilings.

In the past we have used typical cardboard baffles and either batts or blown in FG. Recently we did a small project where we cut and fit 2" polyiso for the baffles, with the usual 1" vent space above and foamed the edges, my theory being that this will reduce wind-washing of the fiber insulation and improve air-leakage performance. We also did one with 6" of solid polyiso where there was only 2x8 rafter space available.