Low Profile Roof Vent Leaks

Roof Ventilation Basics

• When it comes to attic and roof vents, more is usually better. Most roof vents are static, meaning they do not contain electric or wind-driven turbines that suck the air up and out of the attic. Static vents depend upon careful placement of exhaust vents, which allow hot air to escape, coupled with intake vents, located in the soffit, that draw cool air into the attic. Soffit vents, which are tucked under the eaves of the roof, are flush or very low profile, but because they are on the underside of the soffit, they rarely leak.

Flashing Leaks

• Low-profile hip and jack vents sit high upon the roof, as near the ridge as possible. Most low-profiles vents feature a round or square shape and come in two parts. The base of the vent is wide, flat and hollow in the middle to allow attic air to escape. The base also has a flat flange that extends along the roof sheathing. A process of layering the shingles both under and over the flange, called shingle counter-flashing, in addition to caulking, diverts rain away from the vent. If either the shingles or the caulking is worn or incorrectly installed, the vent could leak.

Ridge Vent Leaks

• A ridge vent is one of the most visually appealing low-profile vents on a roof, and it’s so well concealed that you might not see it unless you know what to look for. A ridge vent runs along the entire length of the roof’s ridge and is covered with shingles so it appears to be part of the roof. Beneath the shingle lip, the horizontal, louvered vent may leak if rain blows up and under the protective shingles, although the louvers will block most rains.

Snow

• What appears to be a leak around a vent might be melting snow in the attic. While most roof vents block all but the strongest rainstorms, powdery snow can blow into low-profile vents and collect in a little snow pile in the attic. As the temperature in the attic rises, the snow melts, making it appear as though the vent is leaking.