Flat Roof Against Wall

Housewrap creates the foundation.

Flat roof against wall.

In the case of the perpendicular gable the roof rafters are parallel to the wall the rafters that form the wall side gable are flush against the wall and the ridge board at the peak of the roof. The sheet acts as a backup at a vulnerable junction. Flashing must be applied along the gap between the flat roof and the brick wall to ensure that everything is watertight and secure. Step 3 flashing angled roofs with the step method you can use the step method to flash an angled roof.

This makes it very simple however it does create a weakness in the design. You have to install the roof side of the flashing either under the last layer of shingles or over the roof materials if the roof runs flat up against a brick wall. When building a single story flat roof addition on a two story house the flat roof will normally simply butt up against the side of the wall. You need step flashing which is metal flashing that is in an l shape.

A base flashing and counter flashing are typically used. Sheet of housewrap or even better a piece of self adhering roof underlayment to the wall before the first truss or roof rafter is placed against it. If the membrane is asphalt built up or modified bitumen a cant strip is typically used. If the roof runs flat up against the brick wall you must install the roof side of the flashing either under the last layer of shingles or over the roof material if it is metal.

Follow the photo for illustrated instructions. Ideally i like to start by installing a 3 ft. For example a one story garage with a flat roof may be attached to a two story house. Flat roof and flashing against brick wall install base flashing under shingles or over metal roofing material.

Below are two photographs of roof wall step flashing completed and effective of a slate roof against a brick wall below left and in process with step flashing against a dormer sidewall before the dormer siding has been put in place below right. Here is an attempt though maybe not a very good one to make the roof flashing serve also as a through the wall flashing with a tile roof.