How to Install a House Truss

Get on a ladder to reach the wall caps. Use a tape measure, marker and speed square to draw a line across a wall cap 1 1/2 inches in from the end of the back wall; that marks the first truss. Measure in 23 1/4 inches and draw another line across the wall cap, with another line 1 1/2 inches in from that, for the second truss. Measure 24 inches from that inside line and mark another pair of lines 1 1/2 inches apart, then continue down the wall making 1 1/2-inch spaces every 24 inches. Mark the second wall the same.

Lift the first end truss to the roof, upside down. Have workers on ladders or scaffolding lift it until roof workers can grab it and carry it into place. Use workers with lifting poles as an alternative; cut notches in the ends of 2-by-4-inch boards to hold the truss ends, lift the truss upside down and walk it down the roof to its location for roof workers to raise.

Set the first truss in place between the end marks and stand it up. Use a level to get it plumb. Have roof workers nail it to wall caps on both sides, two nails on the inside edge of the truss and one on the outside edge. Nail 2-by-4s to both sides of the trusses with framing nails and a hammer and to stakes in the ground outside to brace the wall temporarily.

Lift and erect all other trusses the same way. Fasten them to wall caps and brace them temporarily with 1-by-4-inch purlin boards nailed between trusses on the outside. Check each truss to make sure it is properly spaced on the marks and is perfectly plumb. Add permanent bracing according to a roof plan once all trusses are set and remove the temporary braces.

Finish truss installation by putting truss and hurricane clips on the bottom chords of all trusses. Screw truss clips, L-shaped metal brackets, to truss chords and interior wall top plates where those elements meet. Use a screw gun and four screws per clip. Place hurricane clips on the ends of trusses at the wall cap. Nail these with galvanized nails, two nails in each truss chord and two nails in the wall cap boards.