Welcome to Thomas Ford Roofing Company
Roofing Specialist In Modesto, California
Roofing Specialist In Modesto, California
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Should I tear off my old roof or just roof over it?
Complete removal of the existing roof system is mandatory if it
contains moisture, or if the additional roof layer exceeds safe load
design, or if local codes require that the existing roof be removed.
Most local codes will only allow two layers of 3-tab shingles.
A second layer of shingles can be installed over Dimensional /
Architectural style shingles, as the weight would meet most local
code requirements.
Installing shingles over an existing roof system requires proper
preparation of the surface. Blisters, splits and other roof membrane
or flashing defects should be repaired in accordance with good
roofing practices to attain a surface which is smooth, dry, clean and
free of sharp projections and depressions. If the roof is not smooth
and flat, the flaws will project and be seen through the new roof.
Finally, the service life of the new shingles should be considered.
The U.S. Department of Housing and Urban Development performed
a study which concluded that as much as 25% of the service life of
the new shingles will be lost when installed over an existing layer of
shingles due to heat retention.
Complete removal of the existing roof system is mandatory if it
contains moisture, or if the additional roof layer exceeds safe load
design, or if local codes require that the existing roof be removed.
Most local codes will only allow two layers of 3-tab shingles.
A second layer of shingles can be installed over Dimensional /
Architectural style shingles, as the weight would meet most local
code requirements.
Installing shingles over an existing roof system requires proper
preparation of the surface. Blisters, splits and other roof membrane
or flashing defects should be repaired in accordance with good
roofing practices to attain a surface which is smooth, dry, clean and
free of sharp projections and depressions. If the roof is not smooth
and flat, the flaws will project and be seen through the new roof.
Finally, the service life of the new shingles should be considered.
The U.S. Department of Housing and Urban Development performed
a study which concluded that as much as 25% of the service life of
the new shingles will be lost when installed over an existing layer of
shingles due to heat retention.
