What is felt roofing?
Felt roofing is a roofing system comprised of modified bitumen felt which is a combination of asphalt and fibres. The new modified bitumen has evolved from an old roofing method known as built-up roofing. Built-up roofing is achieved by applying multiple layers of asphalt between ply sheets to create a watertight layer.
Felt roofing is commonly known under many different names including; modified bitumen, bitumen roofing, bitumen felt, mineral felt, asphalt flat roofing, bitumen sheet roofing and torch on felt. The name torch on felt comes from the installation process which involves the use of a flame torch to heat the felt so that it will adhere to the roof deck.
What is an example of a built-up roof?
Built-up roofing essentially means a roofing system created from multiple layers. Torch on felt is a great example of a built-up roof as it is commonly installed in multiple layers to increase its durability. The layers often include fibreglass to increase the strength of the whole system.
Torch on roofing can be used as a single ply roofing application, however this isn’t advised as bitumen felt as a single layer doesn’t provide durability.
Is bitumen felt still used in flat roofing?
Yes, bitumen roof felt is still used by many contractors today. Felt roofing that was installed many years ago will likely be suffering from weathering as it is a brittle product that can easily tear and rip. This can cause severe issues such as damage from damp and leaks. Replacing roof felt is often complex and costly as it can only be repaired by a trained installer.
Although felt roofing is still used by many contractors, alternative roofing membranes with easier installation and longer life expectancies such as EPDM are becoming increasingly popular.