Category Archives: Specialized Structure
A significant change to the Ontario Building Code (OBC) was just revealed that positively affects 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 (which is an increase from four storeys) effective January 1, 2015.
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 is regularly seeing projects come through the door with wood frame (probably because of the affordability to the building Owner and the growing demand for mid-rise by the consumer).
While there are certainly challenges with putting 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 eliminates a lot of inboard distance and decreases the force on the structure. This method also pulls the anchor away (perpendicular) upward from the structure which decreases the stress on the structure opposed to pulling horizontally (parallel) with 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 in fashion to reinforcing certain steel structure (like open web steel joist). There are a couple of examples of a wood structure roof anchors below (however modifications can be Engineered to accommodate the structure).
Also, like all projects, communication with us (the roof anchor manufacturer) and the Structural Engineer is crucial as all parties need to know specifically where the equipment is going and understand the load requirements.
You can read the news release at http://news.ontario.ca/mah/en/2014/09/ontario-increases-allowable-height-of-wood-frame-buildings-to-six-storeys.html