Roofing felt is a popular product for what is commonly referred to as roofing. This product is made from various ingredients that include asphalt, tar, bitumen, liquid tar, naphtha, and acrylic. These ingredients are combined in a special formulation to make a strong, durable, and waterproof material that can be used on asphalt based roofs. This material can be applied directly to the surface of the roof. Roofing felt is highly flexible and can stretch to fit any space, including small gaps. It also seals the edges of the roof and prevents leaks from occurring.
Roofing felt is an excellent alternative to traditional felt materials. Traditional felt is typically made from materials such as cedar, paper, or wool. Bituminous coating on the exterior of these materials create a barrier between the wood and the sub-flooring. However, bituminous roofing felt will not provide the same type of insulation benefits because it is not filled with air. Roofing felt is also not a good choice for covering metal roof spaces because it can easily scratch or dent the metal. It is not recommended for use on cold climates because it will not insulate effectively.
Roofing felt layers are applied to asphalt based roofing membranes. A high quality roofing felt product consists of two layers. The first layer is called the impregnating layer and is applied to the surface of the tar paper. The second layer, called the penetrating layer, penetrates the surface of the tar paper and creates a waterproof layer beneath the surface of the tar paper.
Generally speaking, a three inch by six inch area can be covered with one inch by six inch felt. If you have an asphalt based shingled roof then you would be using one inch by twelve inches felt. There are variations in what is considered to be a three inch by six inch area. A one inch by twelve inches areas will cover a standard size roof like that used on a single story house.
When applying felt to asphalt shingles you should first saw the shingles. Use your construction camera or a dark picture frame to view the pattern of the felt. Then see if the felt is level or not. If you find uneven felt you need to make adjustments to the sizes of the sheets you are planning on using. If you are planning on using a larger felt size than what is listed here then you will need to add two to three additional inches to the size of the sheets you are planning on using.
What is roofing tar paper? Asphalt shingles are generally rolled up into a tight bundle and held together with a thin paper or felt paper. The tar paper acts as an added layer over the top of the rolled up asphalt shingles to keep them in place and also to help them weather and resist damage from the weather. If you are trying to install a flat roof then you will need additional tar paper to help the roof to hold its shape.