The roof is the last step in building your bike shed. You can use shingles like I am showing here, or you could use rolled roofing or even a nice metal. But shingles will look good, are readily available, are cheap and will last many years.
If you don’t want to make your shed modular then skip paragraphs 2 and 3 below.
Roof sheeting: After cutting your roof sheeting to size, lay it on top of your shed with the back edge flush with the back wall and even from side to side.
Eliminating the overhang on the back wall will allow the shed to sit directly up against the side of your house.
Now make sure the shed is square to the roof sheeting by measuring the overhang at the front and back edge of both sides of the shed. When all measurements are equal then the shed is square. If necessary you can lift the floor at one or the other of the front corners to make it square.
If you are not making your shed modular you can nail the roof sheeting into the top plates now.
Modular: If you want to make your bike shed modular, then do not attach the roof sheeting yet.
Make a pencil mark on the underside of the roof sheeting where it meets the top plates.
Do this for all 4 sides.
Modular blocks: Now remove the roof sheeting and screw a scrap of 2×4 to the bottom side of the roof sheeting at the middle line where it meets the top plate. One 2×4 block for each of the four walls.
Attach it from the top side with screws so you can adjust the fit if necessary. Then lift it back in place on top of the shed and check for fit.
Adjust your 2×4 blocks as necessary to get a tight fit and make sure the sheeting is still square front to back and side to side. You can either attach it with screws to the shed now or remove it and finish the roof on the ground.
Front flashing: You can save money by skipping the flashing and felt paper if you like. But including them will make a better roof so that is what I’m demonstrating. Cut and attach a piece of galvanized metal flashing to the front edge of the roof with 3/4 inch roofing nails.
Felt paper: Cover the sheeting with felt paper and attach with a roofing nail in each corner. Than put your edge flashing on over the felt paper and nail it down.
Do not put flashing at the top edge just yet because we will put it on top of the shingles to make a water proof edge at the top.
Starter strip: Cut the tabs off a full shingle to make a starter strip. This sticky edge will hold the tab down that rests on it.
Start from the left side with a full strip and cut another piece to finish the row.
Nail the starter strip down and begin your full shingle from the right so the joints will not overlap.
Nail it down with for 3/4 inch galvanized roofing nails just above the tab.
Finish up to the top but make sure you stagger the seams so they will not leak.
Top flashing: To keep the top edge water tight install your last piece of flashing over the top of the shingles.
This is what your finished roof will look like.
I made the mistake of using too long of staples and they were sticking through the sheeting. This would not allow the finished roof to sit flush on the top plates.
So I had to grind them down before I could install the roof.
This gives you an upside down look at the roof with the 2×4 blocks attached. Now lift it in place and attach the finished roof to the shed with two 3 inch screws through each block into it’s matching top plate.
The flashing hangs over the back siding making for a water tight joint at the high point.