Our garage door probably is the original one in our 30-year old house, and I am wondering what the R-value is likely to be.
The exterior is wood, and the interior looks as though it could be Masonite. The door is a couple of inches thick, but I have no idea whether it is hollow or whether it has insulating material in between the surfaces.
What is likely to have been used in those days, and what kind of R-value might it have?
Perce