I’m doing a roof job for a customer in Naperville who just bought a home. The current roof has two layers of shingles on the roof deck. In cases like this the old shingles have to be removed as a third layers would add too much weight to the existing structure. A third layer is never an option.

When we removed the shingles we discovered that 35 sheets of decking plywood had to be replaced due to mold and rot. I usually do a interior attic inspection, but in this case I couldn’t get into the house, and I had to rely on the buyer’s home inspection report. They were in error.

A significant problem with the roof was that it wasn’t vented properly. This allowed condensation to built up which significantly contributed to the rot problem. See the photos below for more details.

Stains on the old roof.
My crew stripping off the old shingles.
Prying off parts of the old deck. You can see the black damage.
Here you can see that there is more damage towards the bottom of the decking plywood. This is where the moisture was trapped.
You can see all of the damage to this sheet of plywood
The roofing material supplier has a lift truck to lift the plywood up to the roof.
One of the 35 boards that we replaced.
Adding the underlayment. You can also see ice and water around the chimney.
The new roof.