A shed roof is one that has a single sloping side. When shingling a shed roof with three-tab shingles (the standard, asphalt-covered, tar-backed shingles used on most residential roofs), you will come to a point at which the top row must be finished with another type of shingle (i.e., ridge cap shingles). Ridge cap shingles are square shingles that you will lay left to right along the top edge, or ridge, of the shed roof.
Determine when to stop laying three-tab shingles and switch to ridge caps. You will know it is time to switch to ridge caps when the non-decorative (adhesive) portion of the three-tab shingles protrude out beyond the top edge, or ridge, of the shed roof. Use a utility knife to trim off the protruding adhesive portions of this top shingle row.
Lay the first ridge cap. To do this, begin on one end of the ridge and place the ridge cap so that the asphalt portion points towards the end of the ridge, and the adhesive points in towards the center of the roof. Drive a nail through the adhesive portion of the ridge cap into the roof decking. Snugly fold the ridge cap shingle over the ridge of the shed and drive one more nail through the facia.
Lay the second ridge cap so that it completely overlaps the adhesive portion of the first ridge cap. Secure it with two nails the same way you did with the first ridge cap. Repeat this until you reach the center of the ridge length.
Go to the other end of the shed ridge and repeat laying ridge caps until you reach the center of the ridge length. The two lines of shingles will meet in the center such that the adhesive portions of the two adjacent center shingles are exposed.
Use a utility knife to trim one of the exposed adhesive portions of the two center shingles such that there is no overlap.
Use a utility knife to completely trim off the adhesive portion of one last ridge cap shingle. Lay the last ridge cap shingle in the center of the shed roof on top of the exposed adhesive portions of the two center ridge cap shingles. Secure the last ridge cap shingle with four nails at the corners of the shingle, and cover the nail heads with roofing cement.