How to Install Roof Trusses
Setting engineered roof trusses safely — from unloading and staging to bracing, setting, and permanent connection.
Step-by-Step
- 1
Review the truss placement plan
The truss manufacturer provides a placement plan showing each truss number, location, and orientation. Read it before the truck arrives. Gable end trusses, valley trusses, and hip sets all go in specific positions — they are not interchangeable.
- 2
Prepare the wall top plates
Snap chalk lines on the top plates for each truss bearing location at the specified spacing (typically 24 inches OC). Mark the center of each truss location. Verify the walls are square and the top plate elevations are equal — unequal walls mean crooked ridgelines.
- 3
Unload and stage trusses
Trusses must be stored upright or flat on multiple supports — never on their side or at a steep angle, which can cause them to bow. Stage them on the ground in order of placement, with the first truss to be set on top.
- 4
Set the first gable truss
Set the gable end truss first and plumb it. This is the reference for all other trusses. Brace it temporarily with 2×4 kickers to the wall framing. It must be perfectly plumb before any other trusses are set.
- 5
Install trusses in sequence
Crane or hand-set each truss onto the bearing marks. Nail through the truss into the top plate and install hurricane ties at every bearing point. Keep the trusses evenly spaced — use a spacing stick cut to the truss spacing dimension.
- 6
Install temporary bracing immediately
Install diagonal bracing per BCSI guidelines as each truss is set. Do not set more than 4–5 trusses ahead of bracing. An unbraced cluster of trusses is a collapse waiting to happen — this is where truss fatality events occur.
- 7
Install permanent lateral bracing
After all trusses are set, install permanent top chord bracing, bottom chord bracing, and web member bracing per the truss engineering documents. Permanent bracing is not optional — it is part of the structural system.
- 8
Apply roof sheathing
Begin sheathing at the eave, working up toward the ridge. Stagger end joints and leave 1/8-inch gaps for expansion. Nail per the sheathing schedule — typically 6 inches OC on edges, 12 inches in the field. Sheathing provides the final lateral stability for the truss system.
Pro Tips
- → Never cut or notch a truss for any reason without a stamped repair drawing from the truss engineer.
- → Photograph every truss placement and hurricane tie connection — inspectors check these specifically.
- → Label trusses on the ground before hoisting — it's much harder to read the tags once they're 20 feet up.
Watch Out
- ! Trusses are unstable until sheathed. Falls from collapsing unbraced trusses are a leading cause of construction fatalities.
- ! Never modify a truss in the field — even a small notch for HVAC can cause structural failure.