Roofing felt is a waterproof fiberglass sheet or tape that is impregnated with tar. It is used as an underlayment beneath shingles or other roofing materials. It is also commonly used for temporary roofing. Roofing felt acts as a moisture barrier beneath the shingles. After they are nailed down, the shingles should be able to prevent water from running down the nails. However, during a rain storm, moisture may gather under the shingles and travel to the wooden surface of the roof. By installing roofing felt, home or building owners can prevent rain from causing damage to their roof decks. In some areas, roofing felt is required as part of the building code.
Those who need to install roofing felt can make the task easier by getting self-adhesive roofing felt. This kind of roofing felt is usually sold in rolls, which can range from two to ten metres in length. The widths of these rolls may vary from 50 mm to 600 mm, with 300 mm, 450 mm and 600 mm being the most popular. There are several different colours for buyers to choose from, including grey, blue, green and others. Certain types of roofing felt can also be used for other purposes, such as sealing roof lights, flues, extractor vents, concrete columns and guttering.