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)":

• Do flat roofs always leak?

• What causes bubble-like blisters in a built-up and gravel roof?  

• Why does it cost so much more to replace a steep roof than a low slope roof? 

• Why are most house roofs slanted instead of flat?

• What is "ponding" on a flat roof?

• Why is there no attic access hatch in the house?

• What is the difference between roll roofing and modified bitumen? 

• What is the purpose of the gravel on a flat tar roof? 

• Can metal roofing be used on a low slope/pitch roof? 

• What is a TPO roof? 

• What is the stuff you paint an old mobile home metal roof with to extend its life?

•  I'm buying a '50s modern house with a "gravel" roof. Is the roof going to be a problem? 

• Is "ponding" (standing puddles of water) normal on flat roof?

• What is a low slope roof?

• What is the average life expectancy of a built-up roof? 

• What is the average life expectancy of an elastomeric roof coating?

 • Can you coat a TPO roof to extend its life? 

• What causes ponding (standing water) on a flat roof?

• What are the signs my flat roof needs to be replaced? 

• What is the average life expectancy of a PVC roof?

    Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.