A tear-off is when the existing shingles, 1 or 2 layers, underlayment and existing nails are removed. Your roof is then inspected for rotten or deteriorated wood, CDX plywood or 1x boards. All necessary wood is replaced to match the existing. Ice & Water Shield is installed on all gutter edges, wrapping the fascia if gutters are to be installed , all valleys and protrusions on the roof. Moisture barrier is then installed on the remainder of the roof and it is shingled to manufacturer’s specifications.

 

If your existing roof is in good condition and it is a standard 3-tab, shingles not a dimensional, you can install a roof directly over the existing roof. You would cut a course of shingles at the bottom edge and install new shingles to manufacturer’s specifications. The draw back on this installation is the following: if your original roof did not include Ice & Water Shield or not the current village code amount you may not be receiving the protection you require for your overhang size. You are also relying on integrity of the original roof installation.