Job Hazard Analysis: Setting roof trusses

A general example for this task. Your JHA should reflect your crew, equipment and site — review it with a competent person before work starts.

Steps, hazards and controls

1. 1. Pre-task meeting and site setup

   • Crane boom or load contacting overhead power linesHigh
     • Call the utility to de-energize or cover the lines if the crane must work near them.
     • Place the crane so the boom and load stay at least 20 ft from lines up to 350 kV.
     • Assign a dedicated spotter to watch the lines during every lift.
   • Wind gusts making trusses sail and swingHigh
     • Check the forecast before starting; the crane operator and foreman stop lifts when gusts make trusses hard to control.
     • Stop work and get off the walls at the first thunder or lightning.
   • Workers struck inside the crane swing radiusMedium
     • Barricade the crane swing radius with caution tape or cones.
     • Agree on one signal person and hand signals before the first lift.

2. 2. Unload and store trusses on site

   • Truss bundle tipping or sliding when bands are cutHigh
     • Land bundles on level, firm ground on wood blocking, close to the building.
     • Stand to the side, not in front, when cutting steel bands.
     • Store trusses upright and braced, or flat on blocking, as the truss supplier shows.
   • Back strain and pinched hands moving trusses by handMedium
     • Use the crane or boom truck to move trusses whenever possible.
     • Carry long trusses with at least two workers, one at each end.
     • Wear work gloves when handling banding and lumber.

3. 3. Rig and lift trusses with the crane

   • Suspended truss falling or swinging into workersHigh
     • Rig at the pick points shown by the truss supplier; use a spreader bar for long trusses.
     • Inspect slings and shackles before each shift; remove damaged ones from service.
     • Control every truss with a tag line; never stand under a suspended load.
   • Hands caught between the truss and the wall or other trussesMedium
     • Guide trusses with tag lines until they are close to the top plate.
     • Keep hands on the sides of the truss, never under or between members.

4. 4. Set and brace the first truss

   • First truss or gable end tipping over and starting a domino collapseHigh
     • Brace the first truss to the ground or to the floor deck with diagonal braces before the crane releases it.
     • Follow the truss manufacturer's temporary bracing plan for brace size, spacing, and nailing.
     • Do not unhook the crane until the truss is nailed to the plates and braced.
   • Falls from top plates, ladders, or the floor edgeHigh
     • Work from ladders, an aerial lift, or scaffold at the walls instead of walking top plates when possible.
     • At 6 ft or more, use a personal fall arrest system tied to a rated truss anchor or guardrails on the floor edge.
     • Extend ladders 3 ft above the landing, set them at a 4:1 angle, and tie them off.

5. 5. Set remaining trusses and install temporary lateral bracing

   • Falls while reaching out to receive and space trussesHigh
     • Stay tied off to a rated anchor at all times above 6 ft; move anchors as the set progresses.
     • Use pre-marked spacing sticks so workers do not lean out to measure.
     • Never stand or walk on unbraced trusses.
   • Nail gun injuries from double-fire or contact triggerMedium
     • Use framing nailers with a full sequential trigger.
     • Keep your free hand at least 12 in. from the nailing point; disconnect air when clearing jams or moving.
     • Wear safety glasses while nailing.
   • Tools and lumber dropping on workers belowMedium
     • Keep the area below the set zone clear and barricaded.
     • Use tool lanyards and hang nailers on hooks, not on top of trusses.
     • Wear hard hats on the ground and in the work area.

6. 6. Install permanent bracing and hurricane ties

   • Falls while working inside the truss webHigh
     • Install permanent bracing from below on ladders or an aerial lift where possible.
     • Remove temporary braces only after permanent bracing is complete.
     • Stay tied off to a rated anchor when above 6 ft.
   • Aerial lift tip-over or worker ejected from basketMedium
     • Set the lift on firm, level ground and inspect it before use.
     • Clip your harness lanyard to the basket anchor point.

7. 7. Cleanup and secure the site

   • Trips and punctures from scrap, banding, and loose nailsLow
     • Pick up banding, blocks, and scrap as you go and put them in the dumpster.
     • Coil air hoses and keep walkways clear.
   • Partially braced trusses collapsing overnight in windMedium
     • Brace every set truss before leaving; the foreman checks bracing at end of day.
     • Do not leave loose trusses leaning on the structure.