Low slope roofing is considered any roofing slope that is less than or equal to 14 degrees. These roofing systems should be weatherproof and always allow for adequate drainage. There are a handful of low slope roofing options to choose from which should support the overall purpose of your structure. Speaking with your contractor to go over what you desire architecturally as well as understanding what is best for the structure of your building will help narrow down your options.
Single Ply Membranes- This roofing system is made of large, factory manufactured sheets which are either made from a thermoplastic material that can be repeatedly softened when heated, hardened when cooled or a thermoset material that solidifies irreversibly by molecular cross linking after it’s been heated. Both can be fully adhered, attached mechanically or ballasted allowing for assembly in all types of weather. Because they are installed in large sheets that are joined together to make one continuous membrane it is crucial that they are installed properly to prevent any leaks. The benefit to this type of roofing system is that it allows contractors to accommodate unique roofing designs because of the flexibility of its material.
SPF Systems- SPF stands for spray polyurethane foam-based system. It fully adheres to the roof through a layer of foam insulation and protective surfacing. The foam base is made of isocyanate and polyol which is heated and pumped to the roof. A spray gun is then used to mix the two components together and then applied to the substrate. The protective surfacing element is an elastomeric coating that is either sprayed or applied by hand providing a weatherproofing coat that protects the foam from UV exposure, assists with fire resistance and protects against mechanical damage. This roofing system requires a dry environment to be installed properly but can be mixed into different ratios to accommodate varying temperatures in the weather. It is an extremely lightweight system that offers durability when proper foam densities are chosen.
BUR– Built up roofing membranes consist of altering layers of bitumen and reinforcing fabrics called felts or ply sheets. These are typically made of glass fiber mats but can also be made from organic or synthetic felts that are saturated with bitumen through the manufacturer. Bitumen consists of either tar or gravel that is heated to a viscosity and then adhered with hot liquid asphalt over the roof ensuring its high durability. These types of roofing systems are assembled on site as they must be applied directly to the roof deck, insulation or a base sheet with an added top layer of pea gravel to protect from UV rays.
Structural Metal Panel Systems– There are two types of metal panel systems: structural or architectural. The structural metal panel system is used for flat roofs due to its strength and water barrier characteristics. Architectural metal panel systems are more commonly used in steep slope roofs because of their design capabilities yet do not offer a watertight seam. Structural metal panel systems are engineered to be strong and durable rather than focus on appearance.
Mod Bit- Mod bit or modified bitumen is a roofing system made of manufactured sheets of bitumen usually composed of asphalt that has been modified with either atactic polypropylene or styrene butadiene which gives the sheets their plasticized or rubbery quality. It is a single ply material that is welded together by heat and applied with a cold adhesive or self adhering backing. Upfront it is the most economical choice however it also needs to be replaced more often.
Structure, traffic, weather conditions, design, code requirements and budget will all come into play when it comes to which type of roofing system will be the best fit for your building and your roofing contractor will be there to help you choose which low slope roofing system will work best for you.