EPDM vs. Felt: which one is better for your roof and why?
EPDM, or Ethylene-Propylene Diene Monomer, is a high-density membrane, which is impermeable to water. In the flat roofing industry, it is fast becoming one of the most widely used synthetic rubbers. The rubber can withstand some extreme weather conditions and comes with a long list of benefits.
Felt, on the other hand, still remains a popular choice. It is a waterproof material and can be applied on any flat roof by torching to create a smooth finish. Felt is also often used under slate or tiles as an extra layer of protection.
While both these methods are popular, EPDM is clearly a more preferred method for flat roofing because of several factors. Let us examine these categories to see what makes EPDM so special.
- Life Expectancy & Cost
EPDM rubber lasts a lot longer than felt, with warranties varying between 20-30 years and a life expectancy of about 50 years. Here at Rubber Flat Roof, we offer the highest warranty in the market on our thickest membrane of 1.5 mm EPDM rubber, while the lower 1.2 mm one comes with a 20 years warranty.
Felt usually has a much shorter life expectancy of around 10-15 years and a little cheaper than EPDM rubber. So initially, even if the price is slightly lesser than EPDM, overall the cost actually ends up becoming more when you consider that you have to redo the roof again within 15 years.
- Single sheet of membrane
EPDM rubber is usually dispatched as per the size of your roof. It has few or no joints, thus making it less prone to damage or leakage in the future. The membrane also remains flexible so it does not crack easily. In case there is a small damage, it can very easily be taken care of by a small repair kit.
Felt is not only more prone to being damaged by extreme weather conditions, it also requires a skilled tradesman to do the repairs, even if it is something as small as a crack. The repair can also look patchy as new felt is torched on the damaged area to repair it.
EPDM is cold applied, meaning no flame or heat is required for installing the rubber. Whereas felt requires to be torched on and has a far more complicated installation process. This is why EPDM is a DIY choice for most as people can install it themselves. Felt requires professional installation and is time consuming. It also raises the risk of fire related incidents because it requires torching and must be handled carefully. On the other hand, EPDM is very simple and quick to install. All it requires is a dry day and some hours of your time to make the roof weatherproof.
- Better for the environment
EPDM is the best choice for the environment as well. It does not leech dangerous oils or Phalates when rainwater runs down the roof, unlike other roofing systems. EPDM remains unaffected by water and vice versa. Thus, any rainwater that gets in contact with EPDM is still perfectly usable and when it goes into the soil, does not make it poisonous. This is also the reason why EPDM is a great pondliner material, as it does not affect the quality of water for the aqua life. Felt is a bitumen product which contains a crude oil that is not considered to be sustainable. EPDM is the better choice between the two.