Some parts of your roof and exterior walls are more prone to leaks and water damage than other areas. These areas include roof valleys, the intersection between a dormer wall and the roof surface, chimney and skylight perimeters.  In other words, anywhere runoff is heavy or where two different opposing surfaces meet. These areas require the extra protection that flashing provides.

Roof flashing is usually made of rust-resistant metal–galvanized steel, aluminium, or copper.  

There are several types of flashing and several reasons why flashing may be a leak source:        

• Metal Counter flashing Problems
• Penetration Flashing Problems
• Drain Flashing Problems
• Gravel Stop and Metal Edge Strip Problems

 Metal Counter flashing Problems—Counter flashing is used where two opposing surfaces meet. Examples of metal counter flashing are chimney, dormer, and valley flashing.  Some common metal counter flashing problems are: 

• Metal deterioration caused by a lack or loss of protective coating.
• Cracks and open joints between metal pieces.
• The separation of counter flashings from vertical surfaces.
• Fasteners not being sealed.
• Counter flashings not tightly fit to base flashings.

Penetration Flashing Problems—Penetration flashing is used where a hole or entry point must be made on your roof. Some examples where there may be penetration problems are roof vents, plumbing stacks, and skylights.
Common penetration flashing problems are:

• The failure to properly design the flashing for the penetration.
• Open or broken seams in metal curbs caused by expansion and contraction—common in skylights.
• Standing water behind penetration curbs caused by the omission of crickets.
• Sagging or separating base flashings caused by omission of top wood nailers.
• Splitting or separation of the felt stripping over the edge of metal flanges.
• Improper priming and stripping of metal surfaces.
• Movement between stack vents or pipes and the flashing.

Drain Flashing Problems– A roof’s drainage system includes the eaves trough, leaders, drain openings and scuppers, as well as the slope provided by the structural deck, tapered insulation, crickets and sumps. The primary function of the drainage systems is to prevent the retention of water on the roof by removing water from the roof as quickly as possible.
Common drain flashing problems are:

• Inadequately designed or improperly installed drainage systems like using only one drain,
• Failure to install overflow scuppers in parapet walls,
• Poor placement of drains next to support columns instead of at points of maximum deflection, loose or missing drain clamping rings.
• Ponding or pooling water is an indication of inadequate drainage, and may point to the presence of structural defects.
   

Gravel Stop and Metal Edge Strip Problems—Gravel stops and metal roof edge strips are used to close off the edges of the roof to prevent wind damage or blow-offs. Another important function of gravel stops is to prevent the loss of aggregate surfacing near the edge of the roof.
Common problems with gravel stops and metal edge strips are:

• Leakage through open or broken joints between metal pieces,
• Splitting of the stripping felts at metal edges.
• Not using scupper cut outs where water must drain over the metal edge

At Mrroofrepair.ca we see many common roof flashing problems and are well versed on how to fix them to stop your roof leak.