Pre-Manufactured Wood Trusses AHA (Activity Hazard Analysis / Job Hazard Analysis)
Updated 2026-06-23
A Pre-Manufactured Wood Trusses AHA (Activity Hazard Analysis / Job Hazard Analysis) is the plan that keeps the crew erecting pre-manufactured wood trusses safe through the truss stability and bracing during erection, from the fall during truss erection, and around the truss handling and rigging. Pre-manufactured wood trusses erects factory-built wood roof/floor trusses — combining the truss-stability and bracing-during-erection hazard, the fall-during-truss-erection hazard, and the truss-handling and rigging hazard. This guide walks through building a Pre-Manufactured Wood Trusses AHA that names the truss-stability/bracing-during-erection, fall-during-truss- erection, and truss-handling/rigging hazards and assigns the bracing, fall-protection, and handling controls that hold up in the field.
Why pre-manufactured wood trusses needs its own AHA
Pre-manufactured wood trusses is the erection of factory-built wood trusses — the engineered, pre-manufactured wood roof and floor trusses (metal-plate-connected wood trusses) set and braced to form the roof/floor structure. This continues the engineered-lumber cluster. The defining feature is the truss erection, which has a specific, deadly, and well-documented defining hazard: like all trusses, pre-manufactured wood trusses are unstable until braced, and the collapse of unbraced or inadequately braced wood trusses during erection — including domino-collapse of a row of trusses — is a leading cause of death in truss erection, specifically addressed by truss bracing requirements and industry guidance. The hazards combine the truss-stability and bracing-during- erection (wood trusses are unstable until braced — the stability hazard (an individual truss and a row of trusses are unstable until braced — an unbraced truss can buckle or topple, and unbraced trusses can domino-collapse, a leading truss-erection fatality — requiring temporary and permanent bracing per the bracing requirements)), the fall-during-truss-erection (erecting the trusses at height — the fall hazard (roof/floor truss erection at height)), the truss-handling and rigging (handling and rigging the trusses — the handling/rigging hazard (trusses are large and can be long/floppy, and mishandling can damage or destabilize them)), and the tool/connection. The truss-stability/bracing-during-erection and the fall-during-truss-erection justify a dedicated AHA.
Breaking pre-manufactured wood trusses into steps
The steps for a Pre-Manufactured Wood Trusses AHA follow the erection:
- Plan the truss erection (bracing plan, sequence, fall protection)
- Set up fall protection for the truss erection
- Rig/hoist and set the trusses (handle without damage)
- Install the temporary bracing as each truss is set
- Brace the truss run (prevent tipping/dominoing)
- Verify bracing before loading/sheathing the trusses
- Install permanent bracing and sheathe per the sequence
- Complete
Each step carries a hazard, and the truss-stability/bracing-during-erection, the fall-during-truss-erection, and the truss-handling/rigging are where the most significant risks concentrate.
The hazards step by step
Truss-stability and bracing-during-erection
Wood trusses are unstable until braced — the stability hazard (an individual truss and a row of trusses are unstable until braced — an unbraced truss can buckle or topple, and unbraced trusses can domino-collapse, a leading truss-erection fatality — requiring temporary and permanent bracing per the bracing requirements). The controls are bracing the trusses during erection (pre-manufactured wood trusses are unstable until braced — a single erected truss can buckle or topple, and a row of erected but unbraced trusses can domino-collapse (one truss falling into the next, collapsing the whole roof), which is a leading and well-documented cause of death in truss erection; so installing the temporary erection bracing as each truss is set (ground bracing, lateral bracing, and diagonal bracing per the truss bracing requirements and the truss manufacturer's/industry bracing guidance), bracing the truss run to prevent tipping and dominoing, and not loading or removing bracing before the permanent bracing and sheathing are in place), and the stability/bracing controls. The truss-stability/bracing- during-erection is the primary defining hazard — unbraced wood trusses collapse and domino, a leading fatality. (These follow the truss-bracing fundamentals.)
Fall-during-truss-erection
Erecting the trusses at height — the fall hazard (roof/floor truss erection at height). The controls are fall protection for the truss erection (erecting and working on the trusses at height — fall protection, safe access), and the fall controls. The fall-during-truss-erection is a defining hazard — truss erection is at height. (These follow the fall-protection fundamentals.)
Truss-handling and rigging
Handling and rigging the trusses — the handling/rigging hazard (trusses are large and can be long/floppy, and mishandling can damage or destabilize them). The controls are safe handling and rigging of the trusses (wood trusses are large and can be long and floppy — rigging them at the correct pick points to avoid damaging or buckling them, controlled setting, and not damaging the truss plates/members, since a damaged truss is compromised), and the handling/rigging controls. The truss-handling/rigging is a defining hazard. (These follow the rigging fundamentals.)
Tool/connection
The tool and connection (fastening the trusses and bracing — nail guns, tools) carries the tool/connection hazard. The controls are safe tool/nail-gun use (fastening the trusses and bracing), safe connection, and the tool controls. (These follow the nail-gun fundamentals.)
A simple Pre-Manufactured Wood Trusses AHA structure
| Step | Hazard | Control | Standard |
|---|---|---|---|
| Plan | Truss collapse | Plan the truss erection (bracing plan, sequence, fall) | project |
| Fall protection | Fall | Set up fall protection for the truss erection | OSHA 1926.501 |
| Set trusses | Struck-by | Rig/hoist and set the trusses (handle without damage) | project |
| Temp bracing | Truss collapse | Install the temporary bracing as each truss is set | project |
| Brace run | Truss collapse | Brace the truss run (prevent tipping/dominoing) | project |
| Verify | Truss collapse | Verify bracing before loading/sheathing the trusses | project |
Truss-bracing stability control and erection fall protection
A Pre-Manufactured Wood Trusses AHA centers on truss-bracing stability control and erection fall protection. The truss-bracing stability control addresses the unstable trusses — controlled by bracing the trusses during erection (temporary bracing as each truss is set — ground, lateral, and diagonal bracing per the bracing requirements, bracing the run to prevent tipping/dominoing, not loading or removing bracing before permanent bracing and sheathing), since unbraced wood trusses collapse and domino (a leading fatality). The erection fall protection addresses the at-height erection — controlled by fall protection for the truss erection. And the truss handling, rigging, and tools get handling and tool controls. An AHA built on truss-bracing stability control and erection fall protection, with handling controls, addresses the hazards that define pre-manufactured wood trusses.
From the field: what actually goes wrong
In fourteen years across federal, heavy civil, and industrial projects, pre-manufactured wood trusses erects the factory-built wood roof and floor trusses, and it has one of the most specific, deadly, and well-documented defining hazards in all of carpentry: the collapse of unbraced wood trusses during erection. The truss-stability and bracing-during-erection hazard is the primary defining concern — pre-manufactured wood trusses (the engineered, metal-plate-connected wood trusses used for most residential and light-commercial roofs and floors) are unstable until they are braced: a single erected truss standing alone can buckle or topple, and — the deadly scenario — a row of erected but unbraced or inadequately braced trusses can domino-collapse, one truss falling into the next and collapsing the entire roof of trusses, often with workers on top, which is a leading and well-documented cause of death in wood-truss erection. So bracing the trusses during erection is the critical, life-saving control: installing the temporary erection bracing as each truss is set (the ground bracing for the first truss, and the lateral and diagonal bracing per the truss bracing requirements and the truss manufacturer's and industry bracing guidance, which specify exactly how to brace trusses during erection), bracing the truss run to prevent tipping and dominoing, and not loading the trusses or removing the temporary bracing before the permanent bracing and the sheathing (which brace the trusses permanently) are in place. The domino-collapse of unbraced wood trusses is the defining, deadly truss-erection hazard, and proper bracing is what prevents it.
The fall-during-truss-erection and the truss-handling/rigging are the other defining hazards. On the projects I have run, truss erection is at height (roof and floor trusses), so fall protection for the truss erection (fall protection and safe access) is a control. And the truss-handling/rigging hazard is that wood trusses are large and can be long and floppy, so rigging them at the correct pick points (to avoid buckling or damaging them during the lift), controlled setting, and not damaging the truss plates or members (a damaged truss is structurally compromised) matter. The nail-gun and tool use for fastening the trusses and bracing rounds it out. The AHA built on truss-bracing stability control and erection fall protection is the one that protects the truss-erection crew.
The bottom line
A Pre-Manufactured Wood Trusses AHA names the truss-stability/bracing-during-erection, the fall-during-truss- erection, and the truss-handling/rigging hazards with specific controls — bracing the trusses during erection (temporary bracing as each truss is set, bracing the run to prevent tipping/dominoing, not removing bracing before permanent bracing/sheathing — unbraced wood trusses domino-collapse, a leading fatality), fall protection for the truss erection, and safe handling/rigging of the trusses without damaging them. The truss-bracing stability control and the erection fall protection are the defining concerns. The AHA that manages both is the one that protects the crew.
Frequently asked questions
Why is truss bracing during erection life-critical?
Pre-manufactured wood trusses are unstable until braced: a single erected truss can buckle or topple, and — the deadly scenario — a row of erected but unbraced or inadequately braced trusses can domino-collapse, one truss falling into the next and collapsing the entire roof of trusses, often with workers on top, a leading and well-documented cause of death in wood-truss erection. Controls are bracing the trusses during erection (installing the temporary erection bracing as each truss is set — ground, lateral, and diagonal bracing per the bracing requirements and manufacturer's/industry guidance, bracing the run to prevent tipping/dominoing, not loading or removing bracing before permanent bracing and sheathing are in place), and the stability/bracing controls.
What fall hazards apply?
Truss erection is at height (roof and floor trusses). Controls are fall protection for the truss erection (fall protection, safe access while erecting and working on the trusses), and the fall controls.
What handling and rigging hazards apply?
Wood trusses are large and can be long and floppy, and mishandling can damage or destabilize them. Controls are safe handling and rigging of the trusses (rigging at the correct pick points to avoid buckling/damaging them, controlled setting, not damaging the truss plates/members since a damaged truss is compromised), and the handling/rigging controls.
What is pre-manufactured wood trusses?
Pre-manufactured wood trusses is the erection of factory-built wood trusses — the engineered, metal-plate-connected wood roof and floor trusses set and braced to form the roof/floor structure. Because unbraced wood trusses buckle, topple, and domino-collapse during erection (a leading fatality), the erection is at height (fall), and the trusses must be handled without damage, those hazards apply.
Related AHAs and JHAs
- Glued-Laminated Construction AHA — the related engineered-wood construction
- Wood Framing AHA — the framing the trusses are part of
- Sheathing AHA — the sheathing that permanently braces the trusses
- Formwork Installation JHA — related carpentry/formwork fundamentals
Written by Mustafa Tok, CSP, ASP, CHST — OSHA Authorized Outreach Trainer with 14+ years of international construction safety experience across federal, heavy civil, and industrial projects.