Mass Timber Construction
Mass timber uses large engineered wood panels and beams, such as cross-laminated timber (CLT) and glulam, to build floors, walls and frames up to many stories. The pieces arrive large and heavy, and the work mixes carpentry with crane erection.
- Carpenters
- Erectors
- General Contractors
Hazards
- Heavy lifts: panels can weigh several tons and be wide, catching wind. See Lift Planning and Lift Wind Limits.
- Falls at edges and openings of fresh, flat panel floors. See Leading Edge Work.
- Fire during construction: exposed wood can burn if hot work, heaters or electrical faults are not controlled. See Hot Work Permits.
- Moisture: wet panels swell, grow mold and become slippery.
- Cutting and drilling dust, and long screws or hardware that pinch and puncture. See Wood Dust.
- Slips and trips on smooth panels, wrap and debris.
Lifting and rigging
- Use the lifting points and hardware recommended by the manufacturer, such as embedded screws or slings, rated for the weight and angle.
- Use tag lines and a trained signal person. Do not stand under the load.
- Do not release the crane until panels are fastened or braced as the engineer says.
- Protect panels from slings that crush edges or surfaces.
- Stop lifts in strong wind, since flat panels act as sails.
Fall protection
- Plan edge protection before the first panel is set. Pre-install guardrail posts where possible.
- Use guardrails, personal fall arrest with proper anchorage, or controlled access zones for leading edges.
- Cover or guard openings and stair cutouts promptly.
Fire safety during construction
- Hot work permits, fire watches and extinguishers for any cutting, welding or heat work
- Keep temporary power and heaters clear of exposed wood
- Control smoking and storage of combustibles
- Have a plan for early fire detection and for protecting the water supply and standpipes
- Follow the building's construction fire safety plan
Moisture and protection
Cover stored and installed panels, drain water promptly and dry wet surfaces before closing in. Wet wood is slippery and can grow mold, which is a health risk. See Mold.
Standards & references
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