Ice dams on this new home in Michigan's Upper Peninsula formed above interior cathedral ceilings.
The cathedral ceilings were insulated with low-density open-cell spray foam and were unvented.
The roof sections with no ice are above unheated areas of the home.
By taking surface and air temperature readings on both sides of the foam-insulated garage walls, the author was able to estimate the R-value of the insulation in that location and — by extrapolation — in the cathedral ceiling.
