Roofing paper, sometimes known as tar paper, but more often known as felt, is a very important factor in the roofing process. Everyone has seen that black paper that is put on roofs. And most everyone knows that it goes between the roof decking and the shingles. But not everyone knows the full reason for its design and purpose. If you are interested in doing your own roofing project it would be to your advantage to have a full understanding of why roofing paper is so essential.
Roofing paper or felt is a waterproofing element designed to give an additional layer of protection to the roof decking and building structure that is underneath the shingles. Roofing paper comes in rolls which are commonly 36 inches in width and 36 feet long. This is a coverage of 1 square. It comes in two weights, 15 pound and 30 pound. The 15 pound roofing paper covers about 4 squares where the 30 pound roofing paper covers about 2 squares. Roofing felt is made of natural or synthetic materials which are coated with asphalt for water protection and yet still allows the roofing paper to breathe.
Roofing paper is installed after the roof decking is installed. The decking should be completely free of any debris before the roofing paper is put down. Never apply roofing paper when the decking is wet, the roof decking should be completely dry. The roofing paper will cover over the entire roof decking including valleys, eaves, flashing, etc.
The roofing paper should be rolled out horizontally starting at the edge of the bottom of the roof and work your way up the roof. The roofing paper will be installed in runs that overlap each other so that water will run off each run of roofing paper and not get underneath it. Use roofing nails with nail caps, or plastic washers, to secure the roofing paper to the roof decking. The roofing paper should be overlapped at least 4 inches on each run and nailed about every 8 inches in order to secure it. Trim the edges flush using a roofing or utility knife. When it comes to vent pipes the roofing paper can be cut with a utility or roofing knife and slipped over the pipe. Be sure to keep the roofing paper tight and smooth on the roof decking eliminating any bubbles, wrinkles, or air pockets.
Once you reach the ridge or peak of the roof cut the roofing paper along the ridge and remove it. Cover the opposite side of the roof in the same fashion as the first. When you have reached the ridge peak on both sides of the roof cut a piece of roofing paper that will fit over the ridge peak on both sides by about 4 inches.
Now that you have understanding of the roofing paper product and followed all the steps to install it you are ready to install the roofing shingles. Congratulations.