Chris Butson’s Utah home sits at an elevation of 6,000 feet and experiences everything from sub-zero temperatures in the winter to 100-degree summer days. Built in 1994, the house has what Butson believes is an underinsulated roof that contributes to big electric bills and massive ice dams.
“From what I have observed, the roof/attic was not insulated well when built,” Butson writes in a post on GBA’s Q&A column. “This has been partly remedied by blowing in extra insulation into the attic, but most of the cathedral ceilings were framed with 2x12s with probably 8-inch or 9-inch thick batts of fiberglass. In short, the roof has lots of heat gain during the summer and lots of heat loss in winter.”
To compensate, the builder installed a huge air conditioning unit to make summers more comfortable, as well as hundreds of feet of heating cables along the eaves to melt ice dams as they form in winter. Does it work? No. “Not surprisingly,” Butson says, “our electric bill is quite high and we have massive ice dams.”
Butson has done his homework. His solution includes adding rigid foam insulation of some kind on top of the existing roof sheathing to get the R-value up to 49, adding blown-in insulation to the attic, improving attic ventilation, eliminating skylights, and building a conditioned mechanical room in the attic for the furnace and AC equipment.
“Does this plan sound reasonable, or am I missing something fundamental?” he asks. “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?”