A Leak in a Gable Vent

Gable vents provide a way for the attic to receive fresh air, helping prevent mold growth.
Blowing rain or broken seals around the vent can let water into the attic.Blowing rain or broken seals around the vent can let water into the attic.
If the gable vents become a source of moisture entering the attic, though, they no longer serve their original purpose. Gable vents have slats that are angled down to keep rain out, but if high winds are blowing rain to the side, it may then enter the attic. Tom Silva of This Old House recommends constructing a baffle piece that allows air flow but blocks water.

Step 1

Inspect the gable vent and its seal with the side of the house both from inside the attic and from outside using a ladder. Look for any broken seals between the gable vent and the house and apply silicone caulk to any cracked or broken seals.

Step 2

Trim identical triangle-shaped wood pieces from a solid sheet of wood. Design the triangles so the shortest side is about 6 inches long and the longest side is as long as the gable vent’s sides are tall. Nail the wedges onto the sides of the gable vent from inside the attic, with the 6-inch sides pointing upward.

Step 3

Measure the distance between the triangle pieces you installed. Cut a piece of plywood that is the same width as the distance between the triangle pieces and the same height as the triangle pieces.

Step 4

Place the plywood piece onto the edges of the triangle pieces and drive nails through the plywood and into the triangles. This allows for air flow but does not allow water to come into the attic.

Things You Will Need

  • Ladder
  • Silicone caulk
  • Measuring tape
  • Pencil
  • Solid sheet of wood
  • Circular saw
  • Sawhorses
  • Nails
  • Hammer
  • Plywood