How To Flash A Flat Roof To A Vertical Wall

Roof shingle over step flashing.

How to flash a flat roof to a vertical wall.

One common method is to lay the edge metal under the eaves membrane and over the rake. When the flat roof as on a more elevated position compared to the sloped roof the flashing of the sloped roof extends onto the flat one. Long helps it to fold onto the roof sheathing. I then add a second piece of flexible flashing tape to cover the open corner of the metal flashing and i fold it down onto the subfascia.

The roof flashing is then placed up behind this through the wall z bar flashing on the outside of the vertical blocking backing material. Two ways to flash roof edges. The gravel stop prevents material on the roof from falling off and also serves as a shield to protect the roof from damage. Protect the eave from ice dams and sideways rain step one in steep slope roofing is the edge flashing.

I fold a piece of metal flashing for the inside corner between the subfascia and the wall. Use flashing cement at joints to help secure flashing. Most simply use a nominal 6 piece of lumber. To install the roof wall flashing above the builder bent the top edge of the flashing into a 90 degree lip about 2 cm in width.

Use step flashing that has a 2 to 4 inch longer vertical leg than normal. At roof to wall intersections see figure 1. When fitting cover flashings to a flat roof like the one pictured bottom right there is no need for the third covering angle of lead the lead is simply cut just above the flat roof to stop capillary action and the flashing cutting into the flat roof itself. If you do not wish to form your own corner flashing you can buy pre bent pieces and cut them to size or use a piece of corrugated aluminum which is easier to bend.

And when the flat roof is below the sloped one flashing is applied on the flat one and extend upwards to the slope. The exterior wall covering material is then kept off the surface of the roof. Strips of the roofing material itself are sometimes installed before the membrane attached to the roof perimeter and the vertical surface. Tape the top of step flashing with 4 inch wide minimum self adhering modified bitumen roof tape.

Gravel stop flashing helps protect the fascia from water damage just like the drip edge. Step flashing on roof peak. Bend the corner flashing tightly around the corner. Fastening strips or termination bars may be used to pinch the membrane down to the roof deck or into the bottom of the wall before the base and counter flashings are installed.