A significant change to the Ontario Building Code (OBC) was just announced, positively affecting the fall arrest anchor and tie-back equipment industry. It was recently announced that wood-frame buildings can be built up to six storeys tall in Ontario, effective January 1, 2015 (an increase from four storeys).
Since roof anchor systems are required for maintenance and window-washing equipment on buildings that are eight metres tall (usually over three storeys), our industry will see a dramatic shift from concrete and steel mid-rise to wood-frame mid-rise.
The OBC change reflects codes in most European and some North American areas. Specifically, the change was made in British Columbia in 2009, and our Vancouver office regularly sees projects come through the door with wood frame (probably because of the affordability for the building Owner and the growing demand for mid-rise housing by consumers).
While there are certainly challenges in installing our equipment on wood-frame buildings, there is always a solution.
The equipment should be close to the edge of the building (parapet) and utilize a pinned-down outrigger beam to rig. The close proximity to the parapet reduces the inboard distance and decreases the force on the structure. This method also pulls the anchor away from the structure (perpendicular) upward, which decreases stress on the structure, rather than pulling it horizontally (parallel) to the structure. Check out the pinned-down outrigger beam detail below.
Like all roof anchors, the load requirements are still 1,000 lbs. (working) and 5,000 lbs. (ultimate). So to achieve this, the structure around it must be “blocked up”, similar to reinforcing certain steel structures (like open web steel joists). There are a couple of examples of a wood structure roof anchors below (however, modifications can be engineered to accommodate the structure).
Also, as with all projects, communication with us (the roof anchor manufacturer) and the Structural Engineer is crucial, as all parties need to know exactly where the equipment is going and understand the load requirements.
You can read the news release at News Ontario