Flat Roof Facts

Boyd Construction Co Inc, Flat roof specialist in the Washington DC area

• Most flat roofs are typically not as long lasting or durable as many sloped ones, because the latter shed snow and rain a lot quicker. However, over the last few decades new and advanced flat roofing membranes have been developed that are highly durable, energy efficient and can compete with sloped roofs in longevity.
• There are three general types: 1. Single – Ply 2. Built-up 3. Spray-on/paint-on.
  
• Today, single ply membranes are the most popular flat roof materials used in both commercial and residential construction.
  
•  Built-up roofs are manufactured using built-up layers of either tar-saturated paper and liquid tar with gravel, asphalt, rolled asphalt, or modified bitumen. As the roof is installed, more and more layers are added to increase durability and longevity, hence the name “built-up”.
  
• There are two main types of spray-on roofs:
  

1. Spray Foam Insulation (sprayed directly onto the roof deck and then coated with acrylic or urethane coating, as well as a layer of crushed stones/sand.
2. Roof coatings (manufactured for existing roofs and used to extend their service life by 10-15 years). They are typically installed on top of single ply, modified or low slope metal roofs.

• A flat roof costs less than a pitched/sloped one.
• It is critical to find a contractor who specializes in single ply roofing to ensure that there will be no leaks after installation. Many customers make the mistake of hiring contractors specializing in sloped roofing (asphalt shingles), who have little to no experience with complicated flat roofs.
• Manufacturer warranties offered on different types of flat membranes vary greatly depending on membrane’s thickness, size, method of installation, and environmental conditions.
  
• The biggest problem for most flat roofs is the presence of seams and flashing, because that is precisely where leaks occur.
  
• If no leaks occur, its still recommended to re-seam (apply 6 inch cover tape over all seams) an EPDM rubber every 7-10 years, when adhesive starts to naturally fail. Repairs are done using EPDM peel & stick flashing + EPDM primer (recommended method) or using older black glue. Penetrations are repaired using uncured flashing that can be stretched to form around angled surfaces.
  
• A flat roof is the best material on a very large size building. Installing a pitched roof on such a building is not recommended, because it will be a lot more difficult, and costly. It will also require special engineering to accommodate the additional structural weight, as well as rooftop HVAC equipment and drainage.
  
• A rooftop garden installed on a flat roof improves air quality and reduces the heat island effect in large urban areas.
  

Contact Boyd Construction Co Inc, Washington DC area flat roof specialist for an estimate on repairs or rebuilds.