How to Install Roof Flashing

When installing shingles on a new roof or a re roof you will need to install flashing along walls, dormer and
chimney chases. Flashing is a piece if aluminum 8 to 10″ wide folded on a 90 degree angle to allow at least 4″ to fits against wall and the rest lies along roof. When this flashing is installed up the pitch of the roof it is recommended that it be installed in steps , thus the name step flashing.

This is accomplished by cutting the aluminum into pieces 6 to 10″ long and 8 t0 10″ wide. It should be folded on a 90 degree angle allowing at least 4″ to fit against the wall and remainder laying on shingle above the area that will be exposed. all of the flashing on top of shingle should be covered by the next shingle that is on top of it. This process is repeated up the full length of the wall so that it is in a pattern of shingle, flashing, shingle, flashing and so on until you complete the lay along the wall.

When the wall runs across the roof as in the front of a dormer the flashing is installed in one piece along the length of the wall, This is commonly called pan flashing. The flashing should be folded on the same angle as the slope of the roof or close to the same with at least 4″ running up the wall and 4 to 6″ places under the shingles.

The flashing should be cut to a length that allows for at least 4 ” to extend past both corners of the wall if wall does not reach across entire roof. the 4″ that extends past the wall needs to be folded around the corner. This is accomplished by using tin snips and starting ir the top corner of flashing that is standing up. and cut at 45 Degree angle to a point at the fold that is even with the corner of the wall. Now starting at the end of flashing cut along fold to the end of the angle you just cut and even with the corner of the wall. Fold the angle cut around the corner and tack to wall, repeat the process on the other side of dormer.

Now the flashing running up the wall will be installed in steps with the first piece being cut on angle and wrapped around the corner to the front side just opposite to the last corner process you just completed.Using a caulk gun apply a small amount of silicon caulk to the area of flashing at the overlap around corner at the fold, If the corner is wrapped correctly you will not see through the corner to bare wall.

Now continue up the length of the wall with the step flashing alternating with flashing shingle flashing shingle. Remember to make sure the shingle covers the flashing under it.One rule to follow when installing shingles and flashing or anything else you may install on a roof , If remember two things you will always insure against leaks.The rule is, water runs downhill and you need to keep it on top of your roofing material or flashing. If you will keep this rule in mind and apply it to your situation while roofing you will have a leak free roof .

When you are installing flashing around any part of the roof where corners need to be wrapped you must start at the bottom or front wrap your corners and then install flashing up the walls . If you have a back wall also then wrap corners from side wall around to back wall and then apply back wall flashing and wrap corners around to side wall, apply caulk and finish installing shingles. Using your utility knife cutting and fitting shingles snugly at corners.

If you follow these guidelines you should be to handle any flashing that needs to be done on your roof and do a successful job with no leaks. Don’t rush your job and think out what you are doing. This will make your job easier overall and you will have a completed job with a great appearance when finished This is an extremely important part of your do it yourself task.

Work smart and always practice safety when working especially when working on a roof or ladder. The best practice is to never work on the roof alone> There should always be someone else around for safety.