Roof Underlayment Types

There are 3 main types of underlayment that homeowners can choose from when it comes to protecting their roof.

1. Asphalt-saturated Felt

This used to be the most popular choice for roof underlayment until it was replaced by synthetics. It’s usually known as tar paper or felt paper and it can be made from various mixtures of asphalt, polyester, cellulose, or bitumen.All types of underlayment are made with a basemat, which acts as a flexible base layer. In felt paper, this basemat achieves water resistance with a saturation of asphalt.

2. Rubberized Asphalt

This tends to be the most expensive option for roof underlayment due to higher amounts of rubber polymers and asphalt. This mixture creates a 100% waterproof seal but comes with a steep cost in price.

3. Synthetic Underlayment

This is currently the most popular choice for roof underlayment, and with good reason. Made with an asphalt-saturated basemat and fortified with a mix of fiberglass, this product is not only extremely water-resistant, much stronger and more resistant to tears than other types of underlayment.

The highest quality versions of synthetic underlayment also feature anti-slip properties.

The Enemy: Wind-driven rain and ice dams are the culprits, allowing water to get under a roof’s outer shell — whether it’s shingles, slate, tile, cedar shake or metal. And unless your roof deck is protected with a waterproof barrier, damage is the inevitable consequence. Wind-driven rain can drive water up the slope of a roof, forcing its way under the shingles. In regions with colder weather, Ice dams are those nasty build-ups that form on the gutters and eaves of roofs as freeze-melt cycles take place. The result is trapped water, which has been forced under the shingles, that will penetrate the deck unless properly sealed. Both may result in trapped water which can penetrate the deck, if not properly sealed.

The Defense: WinterGuard® waterproofing shingle underlayment is the solution for winning the battle against water penetration in your roof’s most vulnerable places. WinterGuard is a composite material of asphalt polymers, formed into a rolled sheet. The asphalt makes it vapor-tight, and the polymers make the asphalt elastic and sticky. This protective barrier is able to stretch and seal around nails driven through it. Placing WinterGuard a minimum of 24″ past the interior wall line at the eave provides your first line of defense. WinterGuard is warranted against manufacturing defects and to remain watertight for the same period as the warranty duration carried by the shingles applied above it — up to a maximum of 50 years