Drafts and Comfort complaints, while sitting on the couch in front of a bay window in the TV room.
Bay and bow windows come from tha factory with a plywood sill. In many cases the sills never get insulated. The top surface of this plywood is inside of the house, and the bottom surface is outside!! Often, they leak air as well. This is a ridiculous oversite. The large uninsulated sill contributes to a cold drafty room inside.
First the underside is caulked or foamed to prevent air leaks. Then a 4" piece of Silverglo, foam insulation board is installed under the sill. Then a wood panel is installed over the foam and a finish skirt board is applied to the perimeter.
The result is less air leaks, a warmer room that is easier to heat and lower fuel bills.