If a roof is leaking, it is likely that the leak is at a flashing. Flashing is any material that is used as a transition between roofing and another surface or at a roof penetration, or at a change in plane of the roofing itself. It is usually aluminum or galvanized steel, but can be lead or copper. When used at the edge of a roof it is called a drip edge flashing, but flashing is also used where a roof meets an adjacent wall, at the intersection of two different roof planes—a valley, for example—and at roof penetrations like a chimney, skylight, or roof vents. The construction worker in the photo above is installing lead, stepped flashing at a chimney penetration of a tile roof.

   There are several types of roof flashing defects that we can come across during a home inspection. Here’s some examples

1. Deteriorated/corroded flashing
   
2. Damaged and missing flashing 
3. Roofing used as flashing  
4. Amateur flashing
5. Lifted flashing
6. Caulk or mastic used to repair damaged flashing 

    Having a professional roofer walk your roof every year or two to look for areas that require repair is a good idea. Roof flashing material comes in standard shapes that can be easily replaced for some areas. But, in others, the roofer will have to cut and shape replacement flashing from sheet metal. 

    Also, see our blog post The inspector says that a missing kickout flashing caused water damage inside the wall. What's "kickout flashing"? 

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  To learn more about roofs and attics, see these other blog posts: 

• What is a dead valley at a roof?

• Why is my roof sheathing sagging between the trusses?

• Why is granule loss a problem for an asphalt shingle roof? 

• What are the mistakes to avoid when doing attic improvements?

• What causes roof shingles to curl up at corners?  

• What causes shingles to buckle along a line on the roof?

• What causes leaks at a fake roof dormer? 

• What causes a sagging roof ridge line?

• 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?

• Is an attic required to have a light by the building code? 

• How can I inspect my roof for hurricane damage?

• Why is premature curl of roof shingles a problem?

• How can I tell if a roof has more than one layer of shingles? 

• What are the common problems with attic insulation? 

     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.