Peeling Back the Layers

4 Types of Underlayment You Should Know (Better)

Atlas Roofing
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For homeowners, shingles are the star of their new roof. But as most roofing contractors know, underlayment plays an important supporting role as the first layer of defense against leaks and is a crucial component of every roofing system.

For veteran roofers, choosing the appropriate underlayment is likely a no-brainer. But even the most professional of pros doesn’t always have all the facts!

To help your customers select the best underlayment for their homes (and perhaps serve as a refresher for you), we’ve put together this handy list detailing four types of underlayment, as well as the associated Atlas products:

Asphalt-Saturated Felt Underlayment

Made from organic felt — a type of fabric composed of cellulose fibers derived from wood pulp — that is saturated with asphalt, this budget-friendly option is easy to install, provides a solid base for other roofing materials and acts as a moisture barrier to keep water from seeping into the roof deck.

Asphalt is a hydrocarbon material that is composed of a complex mixture of organic compounds. It is typically a viscoelastic material, which means it exhibits both viscous and elastic behavior when subjected to deformation. The chemical properties of asphalt and the physical properties of the organic felt work together to create a moisture-resistant barrier that helps protect the roof deck from water infiltration.

Atlas offers three types of asphalt-saturated felt underlayment:

Made with specially developed additives and glass fibers that make it more durable and efficient, Gorilla Guard 30 is designed to outperform traditional felt underlayments.

Designed for virtually any type of roof covering, Gorilla Guard 30 is a high-performance engineered underlayment, which is lighter than traditional organic #30 felt, has a stronger substrate that reduces the need for more re-working before shingle installation, and it lays flatter than traditional felt.

Suitable for most standard-pitched roofs, Atlas Roofing’s #15 asphalt-saturated underlayment features a heavy organic mat with high asphalt saturation and excellent tear strength.

Atlas’ #30 asphalt-saturated felt paper underlayment is thicker and stronger than other organic underlayment, offering superior tear strength and more secure footing for roofers in steep-slope applications.

Synthetic Felt Underlayment

For those looking for something a little more high tech, synthetic felt underlayment might be the way to go. It’s a lightweight roofing material made from synthetic fibers, such as strong polypropylene and woven polymeric scrim.

Atlas offers two types of synthetic felt underlayment:

Ideal for standard application in steep-slope roof assemblies, Summit 60 and Summit 180 are premium quality, woven scrim synthetic underlayments that offer enhanced tear resistance, come in 10-square rolls and provide up to 60 and 180 days of exposure, respectively.

Both products also lay flat, while also protecting against moisture and mold growth.

Self-Adhesive Underlayment

Designed to go under a variety of steep-slope roofing materials, including asphalt, metal and tile, self-adhesive underlayment has an adhesive coating that allows it to easily bond to the roof deck, providing a secure and stable base for the roofing material. The adhesive also helps the underlayment stay in place on the roof deck, even in high-wind or extreme weather conditions.

Atlas offers several types of self-adhesive underlayment:

WeatherMaster self-adhesive underlayments feature SBS-modified asphalt membranes, which provide an additional layer of waterproofing protection in extreme weather.

Made from a proprietary fiberglass mat, WeatherMaster Ice & Water 200 is ideally suited for continuous protection against ice dams and wind-blown rain.

WeatherMaster Pro-Grade Ice & Water can be used as a primary underlayment for asphalt shingles and metal roofs. It also features a soft-surfaced polyester face that provides superior slip resistance and walkability.

The skid-resistant plastic film surface of WeatherMaster Flexible Ice & Water is ideal for metal applications and can also be used as flashing tape, offering critical protection along eaves, rakes and valleys.

WeatherMaster Tile aggressively bonds with the foam adhesives used in tile roof installations and can withstand the weight of stacked tiles without slippage or damage. The woven polyester top surface also delivers superior slip resistance and walkability.

Fire Retardant (FR) Slipsheet

As the name suggests, FR slipsheets are designed to make a roof more fire-resistant. They are composed of a base layer of glass fiber mats with a flame-retardant coating.

The glass fiber mats in FR slipsheets provide a strong and durable base for the roofing material, while the flame-retardant coating helps to prevent the spread and penetration of flames through the roof. FR slipsheets are often used in commercial roofing applications to provide an additional layer of fire protection for the building.

In addition to their fire-resistant properties, FR slipsheets can also act as a barrier between incompatible insulation and roof membranes. They can be used in multiple layers to achieve certain fire resistance ratings, as specified by building codes and regulations.

Atlas offers one type of fire-retardant slipsheet:

With a coated-glass fiber mat specifically designed for installation over wood decks or certain combustible insulation, FR-10 fire-retardant slipsheets enhance the overall fire performance of many conventional commercial roof systems and materials, including metal.

Decisions, Decisions

Underlayment is the unsung hero component in a roofing system. And while your customers may not understand or truly appreciate its purpose, you (and we) do.

So, whether you need something that’s budget friendly, high tech, specialized or fire resistant, Atlas has the perfect underlayment product for your next roofing job!