American housing can be divided into a few distinct groups. If you live in the suburbs, you likely dwell under a sloped or pitched roof. Such construction allows for the installation of fiberglass roofing shingles as the primary membrane keeping rain and snow from penetrating into the wood sheathing beneath them. Usually, shingled roofs are guaranteed by the manufacturer for 20-30 years, depending on the thickness and quality of the product.
If you reside inside of the city limits, you may very well have a flat roof. A flat roof is exactly what you would expect…very little pitch or slope to aid in the draining process. These roofs are typically found on houses built in inner-cities between 1900-1950.
Historically, rolls of fiberglass were installed over the older layer of roof covering with the help of hot asphalt in order to adhere a new membrane for protection against the elements. Since flat roofs are problematic with regard to proper drainage, only 8-10 year guarantees were offered by flat roofing contractors. Even then, the flat roofs needed to be coated with a fresh layer of asphalt every three years to keep the warranty in force and valid flat roofs toronto!
As you can imagine, after 30-40 years of continually adding layer after layer of new roofing material over the older layers, the durability of each new layer was reduced substantially. Look at it this way: suppose you placed a piece of duck-tape over a hole in the side of a Styrofoam cup filled with coffee. For a while, perhaps a long while, the tape would do its job just fine, holding the liquid inside the cup. But, after a period of time, the tape would need some help doing its job. At that point, you’d add yet another piece of tape over the old one, extending the protection. Well, once you had about six layers of tape, you might be wondering whether tearing everything off and starting from scratch might be in order.
That’s exactly what homeowners need to do in many cases: remove ALL layers of roofing membrane and haul them away in a dumpster, prior to applying a new roof covering over the original roof decking, which is typically constructed of wood.
Today, homeowners would be well-advised to steer away from fiberglass and hot asphalt on their flat roofs. Instead, rubber roofing material, typically modified bitumin, should be applied over the decking at the existing roof’s base. This material is warranted for 15 years if installed by a professional roofing contractor. He will also replace the drain-box and downspout in the rear section of a flat roof to ensure that all water will drain easily, leaving no puddles on the rooftop. Inside our city, these drain-boxes often need to be lowered by a qualified contractor familiar with flat roofing projects on 60-100 year-old housing. Only then can you be certain that your new roof will last for nearly a generation.