Renovation to address heat gain (summer), heat loss (winter) and ice dams
We have a home at about 6000 feet elevation in Utah. It’s dry, and the temperatures can vary from below zero F in winter to over 100 F in summer. Our house was built in 1994 with some attic space and lots of cathedral ceilings. From what I have observed, the roof/attic was not insulated well when built. This has been partly remedied by blowing in extra insulation into the attic, but most of the cathedral ceilings where framed with 2”x12” with probably 8” or 9” thick batts of fiberglass. In short, the roof has lots of heat gain during the summer and lots of heat loss in winter. It appears that the builders tried to overcome this by installing a huge AC unit (for the summer) and several hundred feet of heat cable (for the winter). Not surprisingly, our electric bill is quite high and we have massive ice dams.
This website is by far the best resource I have found for the issues I am describing, and I have spent several weeks reading articles. I was originally thinking of adding a cold roof, but I now realize that won’t help with a ceiling that is poorly insulated to begin with. Based on what I have learned I am leaning toward the following solutions:
-Add rigid foam insulation (nailboard or SIP) on top of the existing roof sheathing to bring the R value up to R-49 for the cathedral ceilings (we will do this at the same time we replace the roof).
-Add additional blown insulation to the attic to bring it to R-49.
-Improve attic ventilation with soffit vents+baffles and roof vents.
-Get rid of the skylights.
-Build a utility room in the attic so that the attic furnace/AC operates in conditioned air space.
-To the degree possible, move flexible attic ducts into conditioned air space.
Does this plan sound reasonable or am I missing something fundamental?
Why do I never see heating cable in cold regions in Europe? In fact, I have several German friends and colleagues and they don’t even know what I’m talking about. Is my perception correct and if so what is different about the way their houses are built? Obviously the roofing materials are different – many of those homes have tile or steel roofs.