- Provides expansion and contraction control measures for a roof system.
- Provides protection from the weather and UV rays.
- Flashing can accent a roof design.
- Directs water and snow away from vulnerable areas.
- Allows for the installation of roof top accessories like skylight roof decks and solar panels.
What is Metal Flashing?
Flashings are pieces of metal or roll roofing used to prevent seepage of water into a building around any intersection, projection, or termination point on a roof, such as vent pipes, chimneys, adjoining walls, dormers and valleys. Anywhere a roof joins with any structural impediment, a termination point in the roof is created. Flashing is designed to keep out the water while providing expansion and contraction between two difference surfaces.
Why is the Flashing So Important for a Roof System?
Flashings are installed at termination points; simply put a “break” in the roof. These areas are typically the most vulnerable areas in a roofing system. When there is a separation, a crack in the flashing or sealant has deteriorated due to UV rays or weather wearing, water will infiltrate into those areas and eventually cause a roof leak. An undetected roof leak in attics and behind walls may damage the structure of your walls and insulation. The installation of these roof parts are typically the most time consuming and often corners are cut because of the time it takes to install correctly. In our market we often find the roof coverings replaced with the original flashings left in place, painted to look like new. These materials should be replaced during the new roof replacement as they frequently lead to leaks.
Where do you most typically see flashing on a roof?
Metal or PVC-based strips cover the joint between the roof and the chimney. They are bent in the corner and overlapped on one side by the edges of the shingles, and on the other by the cap flashing, which is attached into the mortar joints of the chimney’s brickwork.
Drip Edge / Raked Flashing
This edge metal is designed to provide support to the perimeter edge shingle and promote efficient water direction directing the water into the eaves. This helps protect the underlying wood from rotting. In addition this metal can also prevent animals from burrowing into the overhang and attic.
Metal flashing is usually chosen for dormer windows. Flashing squares are inserted between each row of roofing material. Flashing can also be used as a strip that runs around the dormer and under the roofing material. Unlike other windows in your home, the flashing is also extended into a front apron, which overlaps the roof material.
Flashing around skylights is usually a continuous piece. Skylights are raised using a wood curb allowing enough room for flashing material. If you are reroofing your house you may need to raise or remove your skylight for the installation of proper flashing. Even if your skylight is manufactured with flashing attached, you may need additional flashing.
When metal is being used, the valley flashing should be installed with W-shaped metal rather than V-shaped. This helps provide the expansion and contraction needed where two different materials join. The hemmed edges help control water flow and creates an air gap that resists the capillary migration of moisture from the metal to the roof covering.
Usually found at an exterior wall or façade to enhance the architectural detail of a building. A decorative detail and material can enhance the curb-a-peal and value of the building.
Plumbing Stacks and Roof Protrusions
Typically consists of rubberized flexible materials like neoprene or even copper that can be formed easily into different shapes. These flashings provide protection for pipes, and other round or odd shaped roof protrusions penetrating the roof coverings.
When to Repair or Replace?
It is a good idea to replace the flashings at the same time as the roof covering so that waterproofing materials can be installed behind or underneath as a second layer of defense. Flashing parts of a roof system can be repaired or replaced. It’s important to remember during these repairs, waterproofing materials should be installed prior to the repair. If you have a leak or would like to know about the condition of the flashings on your roof contact us today to book a service call.