Flat roofs are used more often in commercial buildings or homes in arid regions of the country. The term flat roof is actually rarely correct, most roofs that are considered flat are actually a low slope; meaning less than 3inch drop in 12 inches. Truly flat roofs are problematic because there is no drainage and standing water on a roof can cause problems. Most reputable roofers will suggest installing a taper system, which is a way to install angled panels to a roof to create positive drainage. These panels may be made of a variety of material but most are a type of foam or wood fiber. Over these panels the roofer will then install a low slope roofing material. This material may be a single ply such as EPDM or TPO or a Built Up roof containing one or more plies of felts and asphalt with gravel or a cap sheet on top.
Common sense will tell us that more layers of roofing are going to be better at stopping leaks, if one layer fails the others should still protect. Common sense also tells us the more layers the more the cost. You need to balance your decision by using a cost vs. reward system. Remember always that the roofing material is only a small part of the process in roofing. Parapet walls (walls that extend up above the roof line) need special attention, as do scuppers (drainage cut into parapet walls) and any type of mechanical units that might be installed on the roof. Unless you have a qualified roofer that understands the product and system he is using, you may not be satisfied with the end result.
A great (Pueblo) roofer who typically roofs sloped roofs may not be the best choice for a flat roof. When looking for a contractor it is nice to know someone who says “he did a great job for me”, but you should still ask questions like how many of this type of roof have you done? What type of products do you suggest and why? How do you plan on dealing with drainage? What are your plans for ensuring the water drains where it should and doesn’t pond (stay) on the roof? If your roofer uses terms like crickets (a way to divert water around obstacles), taper systems and single ply versus built up; chances are he knows a little about low slope roofing. Ask for addresses of other jobs he’s done like yours and don’t be afraid to drive by and see what they look like, although from the ground it is sometimes difficult to see details. Check with your local building department to see if there are any problems with the completion of the roofing, many building departments have an online service that you can go into and see if a roofer ever failed and inspection and why.
As with anything do your homework and ask questions, a roof protects everything you own so take the time to ensure you hire a good (local Colorado)contractor.
Pam Simmons Pueblo Roofing Expert for RCI 719 250 1961