How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
What is the purpose of the gravel on a flat tar roof?
Friday, July 6, 2018
Gravel provides shade to the top layer of asphalt tar, protecting it from the ultraviolet rays in sunlight. UV rays speed up asphalt deterioration and cracking when the asphalt is directly exposed to sunlight.
Next time you are close-up to an asphalt roof shingle roof, notice that they also have a coating of rock, but it is finely ground granules and serves the same protective purpose. When a shingle roof loses its tiny rock coating, as in the photo below, it means the roof is at the end of its lifespan and the shingles are brittle.
A secondary benefit of the layer of rock embedded in the top flood coat of asphalt is that the white or light tan color reflects the suns rays, keeping the roof cooler. Heat is factor another that accelerates the deterioration of a roof surface. Also, the weight of the gravel helps keeps the roof secured in place.
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Here’s links to some of our other articles about “FLAT ROOFS (LOW SLOPE)":
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