Roof flashings and terminations are one of the most overlooked aspects of the roof system – and one of the most important.
This is because leaks frequently develop in these areas, where the roof joins with walls and chimneys. To help prevent these leaks from occurring, corrosion-resistant metal flashing is typically applied. Metal flashing is effective, because when properly installed, it can help accommodate roof, chimney, wall, or structural movements due to settling, expansion, and contraction.
However, if it isn’t properly installed or maintained, flashing won’t prevent those leaks from occurring.
Roof leaks occur when water makes its way into the interior of the roof structure. Flashing is designed to direct water away from the interior of the roof structure, and to the topside of the roofing material.
Areas where the plane of the roof is interrupted by a ridge, another roof intersecting at an angle, a wall or penetration are the areas most vulnerable to leaks.
Like shingles, roof flashing overlaps and sheds water. Flashing is always constructed in a system to work with the effect of gravity. When correctly designed and installed, flashing can only be defeated by water running uphill. This can happen in the presence of snow, ice or wind-driven rain.
Flashing works in conjunction with the entire roofing system – sheathing, underlayment, roofing materials — to prevent leaking.
A waterproofing shingle underlayment provides a backup that works in conjunction with your flashing system. However, local experience may call for other flashing modifications to withstand weather-related conditions.
Flashing typically consists of:
- “Step” flashing, which is attached to the roof
- “Cap” flashing, which is attached to the chimney or a wall
- “Drip edge” flashing
- “Valley” flashing
(Step flashing is sometimes called “base flashing” and cap flashing is sometimes called “counter flashing.” Often, exterior wall siding serves as cap flashing.)
Metal Cap Flashing
To learn more, visit our Learning Center.
When the fastening for the flashings comes loose, and the flashing pulls away from the seams and joints, then flashing needs to be repaired.
Installing and repairing flashing should only be carried out by a trained professional. However, you can examine the condition of shingles and flashings when you clean your gutters.
Flashing problems – what to look for:
- Loose nails and damage to seals around the edges
- Dried out roofing cement, leaving joints exposed to water
Badly corroded flashing needs to be replaced. To do this, several rows of shingles have to be removed along with the old flashing.
NOTE: New flashing can be exceptionally shiny, especially in contrast to the earthy brick walls of many homes. New flashing can be painted to match the roof.
Juffs Roofing is here to help you! Ask us about repairs or to replace your roof flashing.