- 1). Make the trusses by cutting two rafters and a "collar tie" cross-member for each truss. Determine the number needed by dividing the shed length by 24 for trusses spaced 2 feet apart. Measure the width of the shed to get the rafter run, the length each side must support; the run is half the width, 6 feet on a 12-foot wide shed, for instance. Decide a pitch; a 5/12 roof will slope 5 inches in every foot of run.
- 2). Mark one 2-by-4-inch board as a pattern rafter. Set the point of a framing square at the bottom of one end of the board. Align the pitch mark, 5 in this example, on the thin tongue and the 12-inch mark on the wide blade along the top of the board to form an angle at the end called a plumb or top cut. Draw that line with a pencil.
- 3). Figure the length with a table on the square's blade. Look under the pitch mark, 5, which will show 13, meaning a rafter must be 13 inches long for every foot of run; that would be 78 inches for a 6-foot run. Mark that distance down the bottom of the board from the plumb cut with a tape measure and draw a vertical line 1 inch up into the board. Measure 3 1/2 inches back up the bottom and connect that point with the top of the vertical line to form a triangle notch to fit on top of the wall.
- 4). Add any overhang desired, typically about a foot, and draw another angled line. Figure this like the plumb cut but with the square point at the top of the board. Cut all those angles with a circular saw and use that as a pattern to cut all needed rafters.
- 5). Lay two rafters out with the plumb cuts together and measure from the bottom of the peak halfway down to a horizontal line between the two wall cap notches. Measure a 2-by-4 to fit between the rafters at that point and mark the angles on each end to fit flush between the rafter boards. Cut those "collar ties." Set out all rafter elements and secure joints with gussets cut from 1/2-inch plywood to overlap the seams where the boards meet. Fasten gussets, on both sides of the truss, with 1 1/4-inch galvanized ring shank nails.
- 6). Erect the trusses on the walls, starting at the back. Set them plumb vertically and space them 24 inches apart on centers. Secure each truss with framing nails driven diagonally through the truss end into the wall caps, two nails on one side and one on the other. Add "hurricane" clips, metal brackets that overlap the truss ends and cap boards and are nailed to each with galvanized nails.
- 7). Cover the trusses on each side of the roof with 4-by-8-foot panels of oriented strand board (OSB) cut to fit at the peak and nailed to the trusses. Lay roofing paper over the OSB and install composition shingles. Nail 1-by-4-inch boards on the roof, from end to end, spaced the width of the wood shakes and nail the shakes to the strips on top of the shake, working from the bottom up. Finish with an appropriate cap strip to cover the peak.
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