The Importance of Underlayment on a New Roof

All new roofs need an underlayment, which is a membrane applied to the plywood — or deck — of your roof. It provides an extra layer of waterproof protection prior to the installation of shingles. It resembles a long thin tarp beneath your shingles, made of heavy black felt paper featuring an asphalt layer on its surface. This helps to bond the shingles to the underlayment itself.

It’s important to add an underlayment, especially to low-sloped roofs and high water risk areas of the home. Underlayment also offers another benefit: it boosts fire resistance. This membrane is typically applied in long, overlapping strips designed to keep water penetration at bay. They protect the joints and seams between those plywood pieces as well as form a seal around nails used in shingle installation – which represent vulnerable areas that water can leak into. These membrane strips are breathable, which means your decking can release internal moisture and condensation that tends to build up over time.

As a key component of your roofing system, the underlayment’s importance cannot be ignored.

3 Types of Underlayment

There are three types of underlayment: asphalt-saturated, non-bitumen synthetic underlayment, and rubberized asphalt underlayment.

  1. Asphalt Saturated felts are placed on the deck before placement of the asphalt shingles. This is a dependable and traditional form of underlayment, or at least it was prior to synthetic materials becoming readily available. They’re water-resistant and very flexible, as well as affordable and ready to use.
  2. Non-Bitumen Synthetic is one of the more common types, and will fully cover most roofs without posing too high a cost. Most roofers and homeowners prefer this option – considered an upgrade from the asphalt-saturated underlayment due to its higher water resistance.
  3. Rubberized Asphalt has the best water resistance of all three options, with a higher percentage of asphalt to rubber polymer. It features a protective membrane with sticky backing, leading to a waterproof seal. It will cost you more than the other two options, though.

It’s important to ask your roofer which underlayment type he or she will use. Ask about which materials they use and why, so you can better understand the underlayment option being used in your home for optimal protection.

Contact Hi-Tech Windows & Siding for Expert Roofing Services

Looking to install a new roof on your Methuen home? Hi-Tech specializes in roof installation of all types and can enlighten you about the type of underlayment we use. To learn more or to get a free quote, contact us at 800-851-0900.

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