My Roof Leaks!

One of the most annoying and potentially damaging things that can happen in a school is roof leaks. The most warranty call backs that we receive as architects is roof leaks. So what can be done to reduce the amount of leaks in your roofing system? You will notice that I said 'reduce the amount of leaks' and not eliminate them completely. I honestly do not believe that you can totally eliminate roof leaks in a large structure over a long period of time. All roofing systems take maintenance and over time the amount invested in maintenance will increase no matter what type of roof you have. So what is the best roofing system to use? Many clients will tell me that they want a pitched metal roof "because they don't leak". Well, even pitched metal roofs will eventually leak. The type of roof system you select will largely depend on the design of the school - or vice versa - if you insist on pitched metal roofs, then that will affect the design of the floor plan. For example, pitched roofs such as you have on your house would not work over a compact school floor plan. The span of the roof is so great that the height of the roof would be excessive, over several stories high. So what designers do is create low sloping roofs that can span great distances, but not create excessive volumes under the roof. Don't get me wrong, I like metal roofs but don't expect them to be perfect. If you can limit the amount of penetrations through the roof, then metal is a good choice. There are several roof systems that are used for these low sloping applications. Four Ply Built-Up roofing is one example. This system uses asphalt impregnated fiberglass sheets with layers of asphalt between them, hence 4 sheets or plys, then a top coat of asphalt and gravel. This is a long time proven system and you can get a warranty up to 20 years on this type of system. There are variations of this type of system that use three plys or two plys with various top coats of gravel or modified bitumen sheets. There is also several manufacturers of single ply roofing that use specially formulated thermoplastic coated membranes (PVC or TPO) products. The single sheets are laid and welded together to form a seamless membrane on the roof. These systems also have the added value of a light reflective surface that reflect the sun's rays to keep the roof from absorbing heat. The single ply's typically have a 10 to 15 year warranty. Before going into your building project, know what type of roofing that the design professional is recommending and why. What type of roof can you afford? What type of roof will give you the best warranty? All of these issues need to be thoroughly discussed. As an added value, you may want to employ a roofing consultant to help you wade through the myriad of choices. This is something that we recommend because this professional can help not only in the design of the roof system, but can also be present when the roof is being installed to insure that a proper job is being done. Michael King AIA