Stormproof Your Roof
Self-adhering underlayment provides critical protection in vulnerable locations.
Synopsis: When you’re making sure your roof is safe from water penetration, it’s important to use the right materials in the right locations. In this article, FHB editorial adviser Mike Guertin describes his process for making sure a roof is protected from water infiltration by using self-adhering underlayment in vulnerable locations such as roof valleys, eave edges (to help deal with ice dams), rake edges, roofs to vertical walls (such as dormers), sidewall protection, the bottom of dormer valleys, and joints in sheathing. When working with self-adhering membranes, Guertin cautions that it’s important to work carefully and to adapt based on outdoor temperature, to buy the appropriately sized membrane for the job, and to get a strong bond so that the membrane adheres firmly to the sheathing.
I’ve done enough roof repairs to know that storm water that gets past the shingles and underlayment doesn’t penetrate through the roof sheathing. Instead, it leaks through the joints between panels and the places where the panels tie into other building elements and roof planes.
The first and most obvious areas to focus on when preparing a roof for shingles are roof penetrations such as chimneys, plumbing vents, and skylights. A more thorough approach, though, involves protecting leak-prone areas such as rakes, eaves, valleys, and dormers. Some of these storm proofing details are installed before the underlayment and shingles. Others are layered into the underlayment or roofing so that water is redirected to the roof surface.
Because I’m going to all the trouble with these details, some people ask me why I don’t just cover the whole roof with self-adhering waterproof underlayment. Call me cheap, but I think I’m getting 98% of the benefit of covering the whole roof with 10% of the material.
Working with sticky…