There are many different types of underlayment for roofing, but one thing they all have in common is the need for a good barrier to prevent wind-driven rain from seeping under the shingles. This can be damaging to the structure of your home and its interior. Traditional asphalt felt underlayments are susceptible to tearing and absorb moisture, causing wrinkling through the shingles. In comparison, the more effective, modern roofing underlays are made from a variety of different materials. epdm roofing
Synthetic underlayments are a great option if you’re looking for a high-quality water barrier. These synthetic materials are made from polymer-reinforced plastic, which is strong and elastic. The polymer-reinforced polyethylene products are also waterproof, which is especially important for heavily-storm-damaged areas. Self-adhered underlayments like Polyglass(r) are also great for reducing the labor costs for contractors and offering extra protection from water.
If you’re considering a metal roof, you’ll want to choose a synthetic underlayment, as metal roofs tend to trap more heat. Synthetic underlayment is better for both snow and heat, but you’ll need to research which one is right for you before you make the final decision. A synthetic underlayment will cost between two and five times more than felt paper, so make sure to choose one that is strong enough to handle the temperature of your climate.
While synthetic underlayment is more expensive, it has some hidden advantages. First, it’s recyclable. Synthetic underlayments have low weight, making them easier to haul onto the roof. They also hold up well under high wind exposure. Those benefits are worth the additional expense. Besides being environmentally friendly, synthetic underlayment also improves worker safety. If you’re building a new house, you can choose to use environmentally friendly products such as polyethylene and propylene.
There are two kinds of underlayments: modified bitumen and asphalt. Modified bitumen is made of polymers and is often used in the construction of asphaltic roofs. Usually, the latter is shortened to “mod-bit” and refers to modified bitumen. Besides being a type of asphalt, bitumen is also used to make roofing shingles. Built-up roofing uses bitumen as its core.
The disadvantages of felt underlayment include its weight and moisture absorption. Felt is heavier than synthetic underlayment, making it harder to install and remove. Felt is also prone to tearing, especially when it’s exposed to heat. Felt is also prone to tearing in high winds and strain during the installation. Further, it’s not as durable as synthetic underlayment.
Before synthetic underlayments gained popularity, felt paper was the common material used as an underlayment for roofing. It was made of tar paper and different mixtures of materials. Its basemat acts as a flexible base layer for shingles, and its asphalt saturation results in water resistance. However, felt paper is the most expensive option, and the amount of asphalt and rubber polymers in the felt makes it a more effective waterproof barrier.