A good roofer should be an expert at installing roofing, of course. But roofing jobs need more than roofing—they also need flashing. Even if roofing is perfectly installed, a flashing error can lead to major leaks and rot.
Roofers should install flashing:
- At the perimeter of most roof planes, including at eaves, rakes, valleys, and ridges;
- At penetrations like vent pipes, chimneys, and skylights;
- Where roofs meet walls or dormer cheeks;
- At locations where dribbling water may lead to rot.
In the 2018 International Residential Code, flashing requirements can be found in Section R903.2. According to the IRC, “Flashings shall be installed at wall and roof intersections, wherever there is a change in roof slope or direction and around roof overhangs. A flashing [kickout flashing] shall be installed to divert the water away from where the eave of a sloped roof intersects a vertical sidewall.”
The terms used to describe roof flashing usually refer either to the location or purpose of the flashing. Flashing types include dripedge, kick-out flashing, step flashing, ridge flashing, chimney flashing, vent pipe flashing, valley flashing, skylight flashing, and flashing associated with roof-mounted PV arrays.
Flashing profiles (and flashing methods) vary depending on the type of roofing being installed. Roofers who install asphalt shingles usually use generic flashing pieces that are widely available, while installers of less common types of roofing (including metal roofing and concrete tile roofing) may need to buy proprietary flashing profiles from the roofing manufacturer or bend their own flashing pieces with a brake.
Until about 1970, all roof flashing was made of metal—generally copper, lead, galvanized steel, or aluminum. In recent decades, however, plastic materials, rubberized materials, and peel-and-stick products have begun to be substituted for some types of traditional metal flashings.
For information on different flashing materials, see…
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