Obviously, we can not install roof shingles before first installing plywood on the roof. Cut 4-ft x 8-ft plywood to the length needed. Install them on the roof frame using mix of screws and/or nails.
Once done installing roof plywood, installing shingles on such a small roof is probably the easiest part of the building process. However, before doing so, shingles underlayment needs to be installed first.
It is assumed that you have already covered the instructions to build the foundation, back side wall, front side wall, the rest of the sides and finished constructing roof frame at this point.
Make sure underlayment layers overlap to prevent possible water leakage if any of the shingles get damaged over time.
Start the underlayment from the lowest edge of the roof. Secure the first layer to the roof plywood using Hammer Tacker Stapler or Steel Stapler. Once you have stapled the first layer, run the second layer and make sure they overlap at least 6-inch, wherein the second layer overlaps on top of the first layer.
Once you are done with the underlayment, start installing the roof shingles. It is very important to start shingling from the lowest edge of the roof too as shown on the picture to the left. Continue installing the shingles till you reach the highest peak of the roof.
When you are done with front side of the roof, follow exactly same procedure to install shingles on the back side.
You should have access shingles hanging down for the sides, simply take a utility knife and cut them, forming straight line if possible. It looks much more neater if caught straight.
As you can probably tell from the picture to the right that the shingling of the peak area has not been completed yet.
Your shed should look something like this picture, with only the front side remaining. Let us finish installing the front side siding and then build a custom door.