Flat Roof Against Wall

Step 3 flashing angled roofs with the step method you can use the step method to flash an angled roof.

Flat roof against wall.

Flat roof and flashing against brick wall install base flashing under shingles or over metal roofing material. This makes it very simple however it does create a weakness in the design. Flashing must be applied along the gap between the flat roof and the brick wall to ensure that everything is watertight and secure. 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.

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. 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. It is common for flat roofs to terminate against walls that are higher than the roof. Follow the photo for illustrated instructions.

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. If the membrane is asphalt built up or modified bitumen a cant strip is typically used. You need step flashing which is metal flashing that is in an l shape. 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.

The flat roofing material must go up the wall a minimum of 12 or up the wall and over the top of the wall if the wall is less than 12 high. The sheet acts as a backup at a vulnerable junction. 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. For example a one story garage with a flat roof may be attached to a two story house.

Proper roof wall abutment flashing examples. 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.