Rolled roofing is easy to install and a very economical roofing material to use. It works well for backyard storage shed roofing applications. It is required as an underlayment for most low slope asphalt roofing applicaions and also works well for low slope shed roofs without any additional roofing on top of it.
Rolled roofing comes in a 36" wide roll and is most often used for lower sloped roofs. The installation of rolled roofing as described in this article is for roofs of a slope of 1" per foot or more. These instructions describe the concealed nail method of installing roll roofing.brief steps to installing rolled roofing on your backyard storage shed
Prepare The Roofing: Cut the roll roofing into lengths long enough to cover one run across the shed roof or of 18', whichever fits your shed better, and lay them out on a flat surface to smooth them out. This reduces the chances of wrinkles after the roofing is installed.
Weather: Rolled roofing should not be installed when the temperature is below 50 degrees because the roll roofing material becomes brittle and will more easily crack. If you do need to work with roll roofing when the temperature is below 50 you can warm the material and then unroll it but be careful because the colder it gets the more likely you are to have trouble with cracking.
Clean The Roof Deck: Make sure the shed roof deck is clean and that there are no nail heads or other things sticking up. Rolled roofing is very fragile and easily torn when the surface it is resting on is uneven. The roof deck must be dry before installing the roll roofing, when roofing is installed over moisture it may damage the roofing from below.
Roof Deck Strength: The roof deck should be strong, usually framed with a minimum of 7/16" OSB (Oriented Strand Board).
Install a metal drip edge along the eves and rake edges of the shed roof in the following manner.
The minimum building paper weight is 15 pound but I always use 30 pound because it is heavier which makes it safer to walk on without tearing and provides better protection of the roof. Underlayment has traditionally been made from felt paper soaked in tar, tar paper. Roofing felt is held to the roof using a nail or staple with a plastic cap that keeps the nail from ripping the building paper. Other products are made from reinforced plastic sheeting.
Safety: Do not walk on the underlayment if it is not fully nailed off. It may feel stable but will quickly give way and send you sliding down the roof. Be careful when it is nailed off, it is paper and can rip and cause you to fall.
Fasteners: Install the underlayment with Plastic Cap nails. Regular nail heads will tear thru the underlayment. Put a plastic cap nail every 24 inches horizontally and three nails vertically on the underlayment so that it is less likely to rip when you walk on it or a strong wind tries to lift it. The first row is the hardest because you need to stand above it to nail it on. After the first row is on you can walk on it to install the next row of underlaymet.
First Row: Start at the eve and one end of the roof and roll out about 5 feet of building paper. Square up the underlayment with the drip edge and install the plastic cap nails to hold the paper in place. Install the underlayment so that it goes on top of the drip edge but not over the edge of the drip edge, hold it back about 1/4" from the edge.
Successive Rows: Continue up the roof and overlap on top of the lower row by 2". There is a mark on underlayment material at 2" from the edges to help guide the successive rows. Cap the ridge after you have done both sides of the roof.
Owens Corning roofing recommends the use of a large head roofing nail that is 3/8" diameter or larger. The Nails should be long enough to penetrate into wood deck at least 3/4", or completely through plywood deck or OSB a minimum of 1/8".
Verify that the manufacturer of your rolled roofing requires a starter strip before installing one. Just like installing asphalt shingles you will begin by installing a 9" wide starter strip along the eves and rakes of the roof. Cut 9" wide x 18' long strips of roll roofing and install them in the following way:
Lift the edges that are over the starter strips and apply lap cement to the starter strips. Press the roll roofing into the lap cement on the starter strips making sure there are no wrinkles.
Where two pieces of rolled roofing need to be joined together at the ends you will need to install an end lap. End Lap joints should be staggered as you go up the roof by about 12". If you end up with two end laps in line with each other you should cut the upper one back 12". An end lap is installed by:
The second and remaining roll roofing courses are installed in the same way as the first course with these additions:
Hip and ridge caps cover the transitions at the hips and ridges. Lean to shed roofs do not have ridge caps but regular backyard sheds with a gable roof design will have ridge caps.
Resources: Owens Corning Roofing, Gaf Roofing