Putting a Truss Roof on Building

Mark truss locations on both outside wall caps, using a ladder, a tape measure, speed square and marker. Start at the back end of one wall. Measure 1 1/2 inches in and draw a line across the cap for the first truss. Measure 23 1/4 inches from the wall end and make another line for the outside line of the second truss; add a line 1 1/2 inches farther for the inside of the second truss.

Measure 24 inches from that inside line and mark another pair of 1 1/2-inch spaces. Continue down the wall marking 1 1/2-inch truss spaces 24 inches apart; the last space may be slightly under 24 inches. Mark the other wall the same way; be sure the spaces are the same on both walls.

Set the first truss in place at the back of the roof. Lift it upside down with workers on ladders or scaffold or using lifting poles for workers on the roof to set it upright. Have roof workers fasten truss ends to wall caps with 16d framing nails driven diagonally with a hammer through the truss into the cap. Put two nails on one side, one on the other. Get that truss plumb with a level and brace it temporarily with 2-by-4-inch boards nailed to the truss and to stakes in the ground outside.

Lift other trusses into place, upside down, let roof workers erect them and nail them to wall caps. Nail 1-by-4-inch temporary braces across the edges of the trusses after the third truss and every three thereafter. Check every truss with a level for plumb before securing it.

Install permanent braces as specified by building codes after all trusses are up. Use 1-by-4-inch purlins or 2-by-4-inch lateral braces, placed across the bottom chords and between top and bottom chords from one truss to another. Install braces in triangular patterns, from side to center and from top to bottom; follow the rules of a code or design of a house plan. Remove the temporary bracing once permanent braces are completed.

Add truss ties and hurricane clips on all trusses. Put truss ties, L-shaped metal brackets, where truss bottom chords meet interior wall top plates; install these with four screws per tie, two into the truss and two into the plate. Put hurricane clips to connect truss chords to cap boards on outer walls; install these with 8d galvanized nails, two nails to connect the clip to the wall caps, two to the truss.

Nail pieces of 1-by-2-inch lumber, about a foot long, vertically to the ends of every truss, as temporary supports for roof decking. Put 4-by-8-foot panels of oriented strand board (OSB) on the trusses, with the rough side of the board out. Lay OSB panels lengthwise, braced against the 1-by-2s, and nail them to the truss rafter chords with 8d galvanized nails.

Butt OSB panels together. Nail on full panels and trim edges and tops as needed to fit the roof with a circular saw. Overlap OSB panels at the peak; let the end of one panel go over the top edge of the panel on the other side.