How-To Do-It-Yourself

Repairing a Leaky Roof with Mastics
By Frank Suster

With all the rain we had this year, many homeowners are attempting to repair their roofs. Flat roofs in Hawaii are subject to extreme weathering. Heat and sunlight bake and eventually the roof membrane becomes brittle and starts to split. Corrugated metal roofs can rust and corrode with Hawaii's salt air. Also, over time, the asphalt-based “plastic cement” used to seal around the pipes, vents and flashing will deteriorate and cause leaks.

Recoating your roof with an aluminum topcoat offers the following benefits:
• It reflects the sun's heat and UV rays.
• It will reduce interior temperatures and air conditioning bills.
• It will lower roof temperatures and roof movement.
• If can dramatically extend roof life.

A word of caution: Climbing on to any roof can be dangerous. Be extremely careful by making sure your ladder is on even, firm footing. Also, on the ground, your extension ladder should be sloped about one-fourth its length from the side of the house.

Before you put a coating of aluminum roof coat on make sure all holes, cracks and splits are properly patched with a good quality plastic cement. Inspect the roof for breaks, splits, holes, raised edges, rusted metal or other signs of deterioration. Leaks often occur where dissimilar materials join, such as where metal flashing is joined to roofing materials. Another likely area of leakage is where pipes and other penetrations stick up through the roof.

To apply the plastic cement you should first remove all dirt, dust, gravel and mud. Wire brush metal to remove rust and scales. The plastic cement should be applied 1/8” to 1/4” thick with a small trowel or putty knife. Press firmly, working the cement into the hole and spreading at least 2” or 4” beyond the repair. If the hole or crack is greater than 1/4” wide or 2” long, embed a glass mess reinforcement fabric between two layers of plastic cement.

Use mineral spirits to clean your tools and a waterless hand cleaner for your hands. When the roof patch is dry, you can now coat your roof. First, make sure you have removed all dirt, dust and gravel. Stir the aluminum roof coating thoroughly and apply at a rate pf 1 to 2 gallons per 100 square feet with a deep pile paint roller or a 4-knot soft bristle roofing brush. Just pour the coating on the roof and spread uniformly.

Always read the label thoroughly before beginning the project.

For City Mill, this is Frank Suster saying, “You Can Do-It-Yourself.”