Many commercial buildings are simply too large for a pitched roof to be feasible. Thus, architects will design a flat roof. With a pitched roof, overlapping shingles are enough to shed water since gravity will send precipitation flowing down the roof surface. You don't have this luxury with a flat roof, so you need to create a roofing system that is completely impervious to water. One popular option is the built-up roof from a place like A-J Roofing & Waterproofing Co. While this system creates a solid roof, you will face the need from time to time to patch your roof.
Layer after Layer: Building a Built-up Roof
A built-up roof begins with a layer of asphalt which installers paint onto a roof. This asphalt is covered with a layer of tar paper, followed by another layer of asphalt, followed by another layer of tar paper, and so on until there are three to five layers of tar paper and asphalt on the roof. By overlapping the sections of tar paper so that the seam of one layers falls in the middle of the tar paper used in another layer, roofers can create a roofing membrane that is impervious to water.
UV Damage: How Leaks form in a Built-up Roof
Built-up roofs are typically covered with a layer of gravel. The gravel does nothing to improve the roof's ability to shed water; instead, the gravel's purpose is to protect the asphalt beneath from the rays of the sun. Even with the gravel, some UV rays get through and dry out the asphalt. Once dry, the asphalt begins to crack. Frost wedging can widen cracks until you have a hole that penetrates through the entire roof surface.
The Patch: Making Repairs to a Built-up Roof
When you find a leak in your roof, follow these steps to make repairs:
1. Pull the gravel away from the leak.
2. Cut two squares of tar paper. Make sure the first square overlaps the crack by two inches and that the second patch overlaps the first by two inches.
3. Paint on a layer of asphalt and press the first patch down into the asphalt until the asphalt bleeds through the patch.
4. Paint on another layer of asphalt and press the second patch down into the asphalt until the asphalt bleeds through.
5. Paint on another layer of asphalt and allow it to dry.
6. Cover the patch with gravel.
While built-up roofs are not indestructible, they are easy to repair. If you have a built-up roof on your building, inspect it from time to time for leaks, and to save yourself money, make what repairs you can on your own.