Is Roofing Felt Waterproof?

An Industry Standard for Years, Roofing Felt Can Protect Your Home or Business for Years to Come

Roofing Felt is a water-resistant layer that acts as a barrier between the elements and your home or business. A standard in the building and roofing industry for years, felt roofing remains popular today for its low cost, durable strength, and exceptional performance.

This blog will look at Roofing Felt in more detail and explore different options as you gather information about what sort of roof your home or business will need.

is roofing felt waterproof

What Is Roofing Felt?


Roofing felt is a water-resistant layer that acts as a barrier between the elements – rain, snow, hail, sunshine, wind, and more – and your home or business. Roofing felt is typically sold in rolls and is rolled out across your roof base – which in most cases is plywood – and applied before the final layer, such as asphalt shingles or metal roofing material, is attached. 

What Is Waterproof Roofing Felt Used For?


Roofing Felt is added as an extra layer of protection and security as part of an overall roofing system. While wood shingles, asphalt shingles, metal layers, or slate tiles are the primary defense mechanism that keeps your home dry and comfortable, Roofing Felt is an additional layer of protection that safeguards your structure from water damage and the threat of other elements.

While shingles and metal roofing do most of the hard work in keeping your home safe and dry, they do have their drawbacks that must be accounted for in the building process. For example, while they do overlap each other, they are not sealed at the corners. If your home or office endures a significant wind event, shingles or metal roofing can be damaged or blown off, which means that water or snow can seep into your home. Shingles in particular can also become brittle and less adept at protecting your home as they age and are exposed to the elements. While brittle or cracked shingles should be replaced, they may also be hard to spot by an untrained observer – meaning that until a professional inspection is performed, your home still needs a backup layer of protection against the elements.

What Makes Roofing Felt Waterproof?


The combination of materials used in the manufacturing process of roof felt is what makes this material waterproof. The bitumen or asphalt used in the felt ensures that water does not soak through the material and reach the roofing base below it. Furthermore, placing the roofing felt between the shingles and roof base adds a layer of protection and prevents water seepage. The rubberized asphalt underlayment ensures the plywood underneath does not get wet. However, felt that is saturated with asphalt only provides temporary defense against water. This means that although felt roofing material is waterproof, a top layer of protection such as asphalt shingles or aluminum roofing is needed for complete protection.

What Is Felt Roofing Made Of?


Most roofing felt sold today is composed of several distinct layers of material. In most cases, there is a base, which is made from natural materials such as wood cellulose or synthetic materials like fiberglass or polyester. This base is then topped with a protective coating such as bitumen or asphalt, which keeps water from penetrating the base material but still allows the material to breathe.

Roofing felt is designed to absorb and then shed water like a sponge. This means that the felt can get wet but still remain waterproof and protect the structure beneath. This allows the roof to breathe. While roofing should ideally be dry when it is installed and also when the shingles above it are installed, it is still possible to install when it is wet. The only real problem with installing shingles when the felt is wet is that it is easier for the felt to tear.

What Are the Different Types of Felt Roofing?


There are several types of roofing felt. In general, roofing felt comes in two thicknesses – 15 pound and 30 pound. 15 pound felt thickness is the standard in most applications, although 30 pound may be called for when additional protection is needed or when the roof in question has a low angle pitch.

Different manufacturers sell roofing with different attributes. For example, felt roofing may be sold in rolls as large as 1,000 square feet or as small as 216 square feet. Others may advertise roofing felt as “premium synthetic roofing underlayment” or as fire-resistant underlayment. Other types include felt reinforced with fiberglass, an ice and water shield that is self-adherent, and peel and stick roof leak barrier rolls.

How Is Felt Roofing Applied?


Felt roofing is applied over the roof base material – which in most cases is plywood. First, drip edge flashing is nailed over the roof edge and down the edge of the facing board on all roof edges. Then, the roofing felt is unrolled beginning at one bottom corner of the roof. It is tacked in place and is run flush along the base of the roof to the edge. The material is attached to the roof base with staples or roofing nails with plastic washer heads. In either case, fasteners are applied roughly every 8 inches, though some are applied more frequently. Subsequent rolls are applied with each roll overlapping the preceding layer by about 2 to 3 inches.

Where Can I Learn More About Waterproof Felt Roofing?


Agave Roofing provides roofing for residential and commercial structures, as well as roof repair and roof replacement. To learn more about how waterproof felt roofing can protect your investment…

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