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Installation of Aluminum Flashing

Ben Wakeling

Roof flashing is an effective way of preventing moisture from entering the joint where a roof is attached to the outside of your home, such as a porch or house extension. It can be fitted in a few hours, and --- although easiest with helpers --- is a task that can be completed by yourself. Lead is commonly used for flashing, but aluminum is a cheaper alternative that is just as effective.

Aluminum flashing should be used whenever a roof meets external brickwork.
  1. Use a stiff brush to remove any loose dust and debris from the wall on which you want to install the flashing.

  2. Determine the length of flashing you need by measuring the joint where roof meets wall. If the total length exceeds that of a standard roll --- which is about 10 feet long --- you will need to use another flashing material, such as lead. Strips of lead can be soldered together, which is not possible with aluminum flashing. Alternatively, you can slightly overlap two pieces of flashing, but this may look odd.

  3. Cut the flashing to the correct size using your tin snips if required.

  4. Use the metal break tool to bend the flashing in half lengthwise, so half of the flashing sits on the roof and half is pressed up against the wall against which the roof is constructed.

  5. Make sure that the metal is flush against the wall and the roof, and hold it in place. You may need a friend to help you with this.

  6. Nail the flashing to the wall and the roof using your hammer and galvanized nails. Make sure you nail as close to the edge of the flashing as you can.