How to Install Rubber Flashing

What You'll Need
Rubber roofing materials
Utility knife
Tape measure
Metal straight edge
Roofing sealant/cement
Metal termination bar
Masonry screws

Rubber flashing is ideal to use with rubber membrane roofs, as it's the same material and gives a continuation of look and fit. Rubber flashing can also be used with other types of roofs, offering greater flexibility than metal flashing while being just as watertight. It’s easy to cut and apply, and there’s very little wastage when using it.

Step 1 - Cutting

When cutting strips of rubber flashing to use, make sure they’re about 24 inches wide. Cut them with the utility knife and use a metal straight edge to ensure you obtain a straight line as you cut.

It’s important that you don’t try to make the strips too long or they can prove difficult to work with. No longer than 6 feet is recommended. If you need a longer run than that, overlap the strips by about 6 inches.

Step 2 - Installation on Metal

Where you’re installing rubber flashing on a roof that meets metal, you need to use a roofing sealant or cement that’s appropriate for the rubber membrane. Check with the manufacturer to see which ones are recommended.

You want to position the rubber flashing so there’s between 12 inches and 18 inches going up the wall and between 6 inches and 12 inches on the roof. Apply a layer of sealant to the wall and the roof and then apply a coat of the sealant to the back of the rubber flashing. Press into place and move along the entire length to take out any air bubbles. If you’re covering an area more than 6 feet long, put the first piece of flashing in place and then use sealant for the next piece, giving an overlap of 6 inches over the first piece and securing with sealant as before. For extra security, always add more roofing sealant over the top edge of the flashing.

Step 3 - Installation on Brick

Where you’ve been putting on a rubber roof that joins a brick wall, you can use the membrane of the roof as its own rubber flashing. Make sure that the final piece you apply against the brick wall is about 24 inches too long. This is the part that you’ll use as the rubber flashing. Secure the roofing in place as instructed. Apply a coat of sealant to the brick and also to the back of the rubber and then press it firmly in place, moving along to force out any trapped air bubbles.

Step 4 - Finishing

To finish you need to have an extra barrier at the top of the rubber flashing. Use a metal termination bar for this. It has beveled edges on a strip of metal. Put it in place so that the screw holes are over the flashing, then screw it into place with masonry screws. This makes a very watertight barrier between the flashing and the brick.