A well-made, durable and lasting roof depends on more than just quality shingles. Homeowners spend considerable time and effort choosing shingles because shingles are the primary, visible element of a new roof. But homeowners seldom give much thought to underlayment because it is unseen.

Roofing underlayment is installed between the roof deck and the shingles, so once the roof is complete it is not visible. However, the choice of underlayment plays a major role in the overall performance and durability of the finished roof system.

Roofers today commonly use two types of underlayment: felt and synthetic.

The Classic Standard: Felt Underlayment

Felt underlayment is typically made of an organic substrate. In some cases, however, such as Gorilla Guard® underlayment from Atlas, the felt substrate is composed of a reinforced fiberglass. Available for several decades now, felt underlayment is suitable for use and is cost effective.

Felt underlayment comes in two levels of thickness: #15 felt and #30 felt. The #30 variety provides better protection than its #15 counterpart because it uses a thicker felt mat and an increased asphalt saturation percentage.  Thirty-pound felt is also more resistant to potential damage during and after installation, and will offer better protection to the roof if exposed to the elements.

Unfortunately, felt does not handle heat or ultraviolet (UV) radiation as well as other options available. Asphalt shingles gradually degrade over time, leaving the underlayment less effective. When felt is exposed to heat or ultraviolet (UV) radiation, the degradation process can occur more rapidly. Heat exposure can be the result of a warm/tropical climate, a particular type of roof-covering material or poor ventilation.

The Advanced Option: Synthetic Underlayment

Synthetic underlayment, such as Summit® 60 from Atlas, is designed to address many of the drawbacks of its felt predecessor. By offering greater strength, better water-shedding abilities and resistance to UV damage, as well as the longer exposure to varying weather conditions, synthetic underlayment has significant advantages over organic felt.

Summit® 60 synthetic roof underlayment is made of a lightweight but strong polymer fabric. It is skid resistant, less permeable than organic felt and more resistant to fungal growth. It also it does not absorb moisture the way felt does.

In some situations, shingle installation might be delayed, leaving underlayment completely exposed to the elements and vulnerable to moisture and UV damage. Synthetic underlayment, however, can withstand such delays much better than felt.

Choose Wisely. Choose Atlas.

The decision to use either felt or synthetic underlayment is an important step in the process of installing or repairing a roof. A comprehensive variety of premium options from Atlas, including Summit® 60 synthetic roof underlayment, provides an additional layer of protection and durability under every shingle. For more information, visit the Atlas website.