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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 wall?

A.Corresponding Editor 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 sheathing.

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.