Trusses are parts of a framework that brace or support a structure. They can be temporary or a permanent part of the structure.
When properly designed, fabricated and erected, trusses are a strong and effective way to support a structure during construction. However, if the design instructions or safety guidelines are not followed, the structure could collapse. Individual trusses can also fail if damaged during transport or installation.
In New Brunswick, a number of truss collapses, many involving roofs, have resulted in serious or fatal injuries.
When constructing a building or structure, both the employers and contractors must ensure that:
- Trusses and any component designed for support are installed completely, before that part of the structure carries any load.
- When a building is being constructed, bracing or shoring for each floor where concrete is being poured is removed only after an engineer’s approval.
- Free-standing walls made of brick, concrete blocks or similar materials are braced from both sides until the wall is attached to a rigid structure and the mortar has set enough to provide the necessary support.
- Free-standing walls or structures designed to support any load, including roof trusses, are braced from both sides until the wall or structure is stabilized.
- Not erected unless the manufacturer’s directions are available on the project site and are set up according to those directions.
Trusses are commonly used in roof construction. When working on roof trusses it is important to remember the best practices for working at heights. Guardrails are the best way to protect workers around roof edges. Guardrails should be installed as close as possible to the open edge and able to withstand whatever loads are likely to be applied against them. Whenever working at heights near an unguarded edge, workers need to use another means of fall protection, such as travel-restraint, fall-restricting or fall-arresting systems.
While the employer is ultimately responsible for all the provisions mentioned above, the supervisor has a vital role to play in the safety of their teams. Supervisors must:
- Acquaint your employees with the hazards and control measures associated with their work
- Provide the information and instruction necessary to ensure their health and safety
- Enforce company safety rules, programs, codes of practice and procedures, including ensuring employees comply with the requirements below.
General Regulation - Occupational Health and Safety Act
N.B. Reg. 91-191
Part X CONSTRUCTION, TRAFFIC AND BUILDING SAFETY
Section 95 Buildings and Structures
95. (1) Where a building or structure is being constructed, an employer and a contractor shall each ensure that
(a) work is completed on any component designed to support or give added support to a part of the building or structure before proceeding with any work that adds to the load on that part,
(b) a free standing wall of brick, concrete blocks or similar materials is braced from both sides until the wall is attached to a rigid structure and the mortar has set adequately, and
(c) a free standing wall or structure designed to support roof components or any load is braced from both sides until the free standing wall or structure is stabilized.
(2) Where the framework of a building or structure is erected in advance of the outer walls, an employer and a contractor shall each ensure that a fall-protection system is used at the perimeter of each floor.
[N.B. Reg. 2010-159, s. 12]
96. (1) Where a building or structure is being constructed, an employer and a contractor shall each ensure that bracing or shoring is retained at all floor levels beneath the floor where concrete is being poured until the removal of the bracing or shoring is authorized by an engineer.
(2) An employer and a contractor shall each provide, if requested by an officer, certification by an engineer that the forms, bracing, shoring and supports for concrete to be used in construction will safely support the intended load.
Section 96.1 Wooden Trusses
96.1 (1) An employer shall ensure
(a) that wooden trusses are not erected unless the manufacturer's specifications for the safe erection of the wooden trusses are readily available on the project site, and
(b) that wooden trusses are erected in accordance with the manufacturer's specifications referred to in paragraph (a).
(2) An employer shall ensure that the manufacturer's specifications referred to in paragraph (1)(a)
(a) are kept on the project site, and
(b) are made available to an officer on request.
[N.B. Reg. 96-61, s. 2]