Every flat roof is the same, isn’t it? Absolutely not. Many homeowners are surprised to learn that there are 4 basic types of flat roof. While the price for these roofs is relatively similar, different types of roofs offer different benefits. If you are considering installing a roof on a new home, you should carefully consider your options and discuss them with an experience roofing contractor. In the meantime, let’s discuss the 3 main types of flat roof: built-up roof, modified bitumen roof, and rubber membrane roof.
Built-Up Systems
These are the most common type of flat roofs and include the traditional hot-tar-and-gravel roof. Featuring at least 3 layers of waterproof material with tar and gravel between each layer, these types of roofs are relatively inexpensive while benefiting from improved technology that makes them more durable. Among the main benefits of built-up roofs is that they offer excellent protection against fire as gravel is an excellent fire retardant. They are also the cheapest flat roof system and are an attractive choice if you have windows that overlook the roof. On the other hand, built-up roofs tend to be very heavy and joists may require extra support. Moreover, installation and repair is not recommended for the DIY-inclined as it can be difficult to find the source of leaks and this system is messy to install.
Modified Bitumen Systems
Modified bitumen roofing systems were first developed in Europe in the 1970s as an alternative to low performance asphalt systems. These are usually single-ply rolled roofing systems that are similar to ice-and-water shields, but they feature a mineral-based wear surface. There are two subtypes of modified bitumen roof: torch-down systems and peel-and-stick systems. Torch-down systems must be heated in order to activate the adhesive whereas peel-and-stick systems do not need to be heated making them safe and easy to install.
Peel-and-stick roofs should always be installed by a professional roofer, but they are easier to manager for a DIY homeowner. However, torch-down application is much more challenging and poses a significant fire risk so should only be applied by professionals. Moreover, torch-down systems should not be installed on occupied buildings. Another benefit of these roofs is that their light-coloured surface helps to reflect heat and reduce energy bills. These types of roof systems are moderately priced.
Rubber Membrane Systems
More expensive than built-up or modified bitumen roofing systems, rubber membrane roofs feature a durable construction made from rubber. Engineered to resist damage from sunlight, rubber membrane roofs are usually anchored with fasteners and may be ballasted with stone or glued.
Rubber membrane roofs are easy to install and the material is very light. These roofing systems are also highly resistant to damage such as scratches or tears and they are also easy to patch. Unfortunately, the black material of these roofs tends to absorb heat so they may require a light-coloured coating to reduce energy costs. Unfortunately, this coating can add as much as 30% to the cost of the roof.