A lot of homes built in San Jose were built between the 1950s and 1970s. As the initial roofing failed, repairs usually meant placing a new layer of shingles over the old ones. Sometimes this happened more than once. We regularly encounter homes with multiple layers of asphalt or composite shingles. The sheer weight of these shingles puts strain on the structural supports of the home. With the number of small earthquakes in the region, any extra weight on the structural supports of a home can result in cracking and potential failure. Relieving this pressure from the roof is one of our number one priorities during a roof replacement. That’s one of the reasons we do full tear offs before putting on a new roof.
Another reason that we do the full tear off instead of simply putting a new layer on is that we can inspect the decking for potential wood rot or water damage. Putting a new roof over one with existing problems is a temporary patch that will need to be fixed again in a very short time. We do patch jobs, but usually only during the rainy season.