If you have a flat roof, it will be easy to install roof felt. Roof felt, often called tar paper, is laid on flat roofs below shingles in case they are damaged to stop water from getting in your home. Roof felt is commonly made from asphalt and sold in rolls. Here are some tips to install roof felt on a flat roof.
Do not lay roof felt in wet or cool weather. If there is existing felt, remove it with hammer or pry bar, being careful not to pull up planks. Inspect the roof for rotted or bowed decking and replace damaged pieces. Unroll the felt and let it stand for 30 minutes so it is easier to use.
Remove extra nails with a claw hammer. Determine how much felt you need by measuring the width and length of the roof and multiplying this figure together for the total square footage and then by three since you will need three layers. For example, if the roof is 12 by 12 feet, the square footage is 144 and 432 when multiplied by 3.
Lay the First Layer of Felt
Cut a roll of felt to fit the roof length with a utility knife. Nail the first layer of felt with roofing staples or galvanized clout nails, making certain the felt stays even while you work. Begin laying the felt from the middle and work out, allowing a two-inch overhang. Place nails each six inches along the short sides and sides connecting to roof edges avoiding the side that faces the roof.
Lay the Second and Third Layer
Trim the next layer of felt to fit the roof length, and then cut it in half vertically to keep the seams from aligning which helps make the barrier. Coat the first layer of felt with a construction adhesive with a trowel pushing the first piece for the second layer on the first layer. Smooth out bubbles with your hands.
Coat the next piece with the adhesive, setting this piece to overlap on the first piece by two inches. Continue laying the rest of the second layer in this manner. Apply adhesive on the second layer using a whole piece of felt and lay each piece to overlap two inches until the roof is covered. Cutting the felt lengthwise isn't necessary for the last layer.
It should be simple to lay roof felt on a flat roof since you don't have to deal with angles. You could cover the felt with gravel for extra stability. If your existing roof is in bad shape, you may prefer to have a roofing company like Pasco Roofing replace or repair it.