Actually, this title is a bit like the old question: "Who is buried in Grant's tomb?" The way you detect a multi-layer roof is by looking. That can, however, be harder than you would expect. The photo below is the simple way, just tweak the shingles a bit and you see another color below. The best place to look is at the eaves or at the gable ends. Sometimes there will be a metal drip edge flashing put over an old roof and that can make it harder to be sure what is below. On the other hand, I did an inspection this morning and the roof was covered with ice and the material so frozen and non-pliable that I was afraid that gently pulling on it would tear a shingle. While most home inspectors like to see only a single layer of composition shingles on a roof, many roofers will put on two layers which usually leaves a number of old metal flashings, sometimes rusted, below the new roof. If there are already two layers, that pretty well guarantees that the next roof will first require a tear-off. If you think about it a concern with multi-layer roofs is weight. If you have ever carried a bundle of comp shingles up a ladder to the roof, you know this is no issue to take lightly -- pun intended. This is a heavy topic.
Thanks for looking.
Steven L. Smith
Bellingham WA home inspector
Check out "This Day In History" -- music and vintage television from the 1950's through the 1980's. I enjoy writing these articles because they take me back to my days in radio broadcasting. Click on Elvis' gold record, below, to revisit those golden hits of yesteryear.
