A low slope roof is any roof under a 4/12 pitch
Low Slope Flat Roofing Installation Methods and Materials Used
Low slope roofing requires completely different products and installation techniques than roofs that have a notable pitch to them. Some roofing materials can be better suited for a slight slope on the roof, whereas other materials can handle ponding water for longer periods of time. Knowing which materials will perform best for your roof application, will give you the knowledge necessary to make sure that you have a roof that will last for decades.
One common material that has been used for many years in low slope roof applications, is modified bitumen torch down material. Installed correctly, it is fairly durable, and is a watertight roofing system. This roofing application carries inherited risks with it. And you should only consult with roofing companies that are very experienced in torch down roof installation. We like to use a granulated cap sheet whether we are doing 2, or 3 ply systems. As long as the water is able to shed itself after the storms are over, modified bitumen torch roofs can handle just about anything the weather can throw at them. There are less qualified torch roofing installers available to do this type of work than there were years before. So finding someone that specializes in this type of roofing can sometimes be difficult.
EPDM Roofing is done using synthetic rubber membrane that can be mechanically fastened, or glued with a rubber cement like industrial glue. Large sections of this material can be purchased to reduce seams on the roof, lowering the chance of leaks due to installation, or premature seam failure. As with torch down roofing, EPDM requires a roofer that is specialized in this specific field of roofing.
Self adhered modified bitumen is similar to torch down roofing, in that it looks very similar when installed, and has similarities in some of the installation practices. This type of roofing adheres itself to the base sheet which is nailed to the roof. It can be done in a 2 or 3 ply system, but we always suggest a 3 ply with this material when it is going to be covering the roof over the interior of a home or building. This type of roofing is very different from torch down, in that it carries none of the same risks to property. A novice can install this system with guidance from an experienced roofer. But it does have its limitations with regards to pitch in how the water sheds from the roof.
One type of roofing that has become very popular with roofs you can entertain on, are PVC roofs that can sometimes be printed to imitate natural materials. This type of roofing can provide a durable surface that can support foot traffic, along with items such as tables and chairs. Installation is often done with either a solvent or water based glue, and the seams are permanently sealed with a heat gun.
There are many other materials that can be used for low slope flat roofing installations, such as TPO, and hot roofs, etc.. They will all have applications that they are best suited for, and being able to install one low slope roofing system, does not necessarily mean that the same skills are required to install another. People that don't have experience with these roofs should always consult a professional roofer for the best systems and proper installation.
The image shown here is a single ply modified bitumen torch down roofing system while being installed. Note the fiberglass base sheet that is nailed to the decking before torching the cap sheet to the roof. 2-ply and 3-ply torch roofing systems are available, and will typically come with greater cost, and extended roof warranties..