- Q.I want to vent an existing
shed roof that intersects a vertical wall at the ridge.
Because this roof is at the front of the house, I
don’t want to place any visible vents in the
roof. Is there an inconspicuous ridge vent available
that can be installed where the roof meets the
Henri de Marne responds: There is a product
called the Flash Filter Vent that is designed for
the application you face. This shed roof vent has a
low profile and comes in dark brown, black, white
and mill finish. It is available from AVI, a
division of CertainTeed (800/247-8368).
The vent replaces the apron flashing normally
installed at the joint between a wall and a shed
roof. It requires removing the bottom course of the
siding and lifting the housewrap or felt paper to
insert its 4 1/2-inch leg against the wall
This vent features an external baffle to deflect
the wind over the vent. The importance of the
external baffle must not be underestimated. I
recently checked a house where a porch roof butts
against a second-story wall. Wind had driven rain
and tree debris — leaves and pine needles
— under the apron flashing and caused the
sheathing and the end of the beam to become wet.
Carpenter ants infested a large structural beam
inside the house. The same situation can occur with
unbaffled ridge vents, as I have seen a number of
time over the years.
I cannot emphasize enough the importance of
inserting any flashing under the housewrap or felt,
so that any leakage from above is directed over the
flashing and not behind it and into the structure.
Too often, flashing is installed over these because
the housewrap or felt was installed first.