Sheds are important storage areas that have to be able to protect your possessions from the weather. This is impossible, however, without a well-shingled roof, as water will just drip through and potentially damage everything inside. Shingling your shed roof is fairly simple and straight forward, fortunately, and if done correctly, it won't need a replacement for some time.
Always put safety first in any DIY project. In this case, wear goggles and work gloves at all times. Take special caution while you are on the roof as well, and wear the appropriate shoes to keep you steady. Any number of accidents can happen while up high, and most of them are caused by negligence; pay attention to where you step and always keep your balance. Using fall protection, a body harness and tying off securely is always preferable whenever you're working at heights greater than 6-feet above ground level. 50% of falls from 20-feet or higher are fatal.
Step 1 - Strip old Roofing Materials
If this is an old shed, you will need to remove the existing shingles before you can lay the new stuff. Use a fork to work the edges lose, and then begin to strip them off with a shovel. Take care where you discard the existing materials for the time being, and make sure to get rid of them properly later.
Step 2 - Apply Roofing Paper
Lay down a good layer of roofing paper along the entire length of the roof, trimming and overlapping when necessary. If there is still some old paper stuck in place, you can reuse it so long as it isn't rotting. If it is, or if you would just rather refresh it anyway, strip all of it off before you add the new material.
Step 3 - Layer the Shingles
Begin shingling at the bottom edge of the roof, starting at one end. Lay the entire first row one at a time, nailing each down with one-inch roofing nails. Place one nail at each corner, a little way in from the edges, and then one, if not two, in the middle. When you reach the other end of the roof, trim any excess off the last shingle with a utility knife.
The next row should overlap the first by at least 1/3 of the shingle and have each one centered over the seam of two in the previous row. Every subsequent row should follow this procedure as well.
A nail gun makes this process go so much faster, but there’s nothing wrong with doing it the old fashion way (with a hammer and some trusty elbow grease). You could use tar as well to hold the shingles down, but that’s a little bit more involved than necessary (still, it’s an option depending on the requirements of your roof and the design you’ve selected). There are a couple of varieties of roofing, and it’s generally good to keep a uniform distance between the rows and shingles. Just eye it and use good judgment (use measurement if needed).
Step 4 - Cap the Top
Do opt to use adhesive on the last row of tiles at the top to get a secure hold. Then, either buy ridge cap shingles or shape regular shingles to fit over this area. Lay them starting from one end and moving to the other, overlapping as you go. Secure these with 1 1/2-inch roofing nails in order to penetrate both layers of shingles.
This method yields durable, waterproof roofs. These roofs will last up to 30 years, depending on the thickness of your shingles, of course, thicker shingles work best in high winds and last the longest but they are the most expensive type. Whichever way you choose to go, you will gain some protected storage space.