How long does a built-up roof last?

You can expect a 4-ply built-up roof to last from 17 to 25 years, with an average of 20 years. Built-up roofs have between 3 and 5 layers of roofing paper, called “plies,” mopped with hot asphalt between each ply. More plies means a longer life, and a rule-of-thumb is 5 years for each ply.

    Here’s a bar graph comparing built-up roof life expectancy of other types of roof coverings.

     Go to our blog post What is the average lifespan of the parts of a house? for rating of other house components. To understand the basis, potential use, and limitations of lifespan ratings, see How accurate are the average life expectancy ratings of home components? Are they actually useful? 

Here’s links to a collection of some of our other blog posts about “FLAT ROOFS (LOW SLOPE)":

• 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? 

• 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? 

• Does a gravel roof need maintenance?

• What is the average lifespan of a built-up and gravel roof?

• What is the average lifespan of a modified bitumen roof? 

• What is the average life expectancy of a TPO (Thermoplastic PolyOlefin) roof? 

• What is an EPDM roof?

• What is the average life expectancy an EPDM roof? 

•  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?

• Why are most roofs slanted instead of flat? 

• What is a low slope 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.

NOTE: These life expectancies are based on data provided by InterNACHI, NAHB, FannieMae, and our own professional experience. Because of the numerous variables that can affect a lifespan, they should be used as rough guidelines only, and not relied upon as a warranty or guarantee of future performance.