3 Factors Supporting a Switch to Synthetic Underlayment

by Marcy Marro | February 1, 2022 12:00 am

In recent years, technology and manufacturing advances have led to underlayment innovations that deliver better performance compared to traditional felt products. Synthetic underlayment has been gaining traction across all types of roofs, including metal. As the name implies, synthetic underlayment is made by weaving together synthetic fibers—typically a polyolefin (e.g., polyethylene, polypropylene) with a polymer coating to form a protective material that defends against moisture.

The three primary benefits of synthetics compared to felt materials are—water repellency, safety and toughness/tear resistance. Below, we consider three reasons contractors who are still using felt underlayment should consider switching to a synthetic material.

1. Repels water
   Data from organizations that track weather trends reveal some regions of the country are experiencing increased annual rainfall. For example, GlobalChange.gov reports that heavy precipitation is becoming more intense and more frequent particularly in the Northeast and Midwest. The primary function of underlayment is to keep liquid moisture off the roof deck. Unlike felt materials which absorb water, synthetics are designed to repel water. As this water repellency attribute defends against moisture intrusion, it also helps make the material inert to mold.
2. Safety
   Materials that complement a safety culture on the roof go beyond worker harnesses and boots. The burden a material places on workers—including its weight—must also be considered when establishing a safety culture. Most synthetic underlayment materials are lighter compared to their felt counterparts. The lighter material weight also complements the design of the rolls. Longer, wider rolls can mean workers need to make fewer trips up and down the ladder to complete a job.

   A typical 27-square residential roofing project requires approximately three rolls of synthetic material. In contrast, about 14 rolls of #30 felt would be required. Looking at these numbers, a job using synthetic underlayment instead of felt could mean 11 fewer worker trips up the ladder. Traction also comes into play and synthetic underlayment is designed to provide a surface with better walkability than felt. Supporting traction and grip on the roof, Titanium underlayment materials feature a patented slip resistant Sure-Foot nodular walking surface technology. The surface allows for easier steep slope walkability, even in wet or dusty conditions.

3. Toughness and Tear-Resistance
   Material toughness and strength are essential on a home’s roof. Synthetic materials are less likely to tear compared to felt underlayments when being walked upon, or when fasteners are installed. The toughness of synthetic underlayments can resist small tears and stand up to boot traffic. In fact, testing data shows that synthetics may be up to 12x stronger than felt.¹

While underlayment is an unseen component of a roofing system, it plays a vital role during installation as it guards against moisture infiltration, supports safety and delivers toughness. By making the switch from felt to synthetic underlayments, contractors can help achieve roofs that offer water repellency, support safety and deliver toughness and tear-resistance.

¹ *Test data is based on average of samples tested in accordance with ASTM D2261.

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Greg Keeler is a technical services leader for Toledo, Ohio-based Owens Corning. For more information on synthetic underlayments and their performance compared to felt paper underlayments, visit the switch to synthetics page at www.owenscorning.com/en-us/roofing/synthetic-underlayment[1].

Source URL: https://www.metalarchitecture.com/articles/3-factors-supporting-a-switch-to-synthetic-underlayment/

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