Retaining Walls
Retaining walls are structures that hold back earth, most retaining walls over 1 meter or 3 feet in height is a designated structure in the Ontario Building Code (and the National Building Code of Canada).
OBC Clause 1.1.2.2 (2) Subject to Articles 1.1.2.6. and 1.3.1.2., Part 4 of Division B applies to, (c) a retaining wall exceeding 1 000 mm in exposed height adjacent to, (i) public property, (ii) access to a building, or (iii) private property to which the public is admitted.
This clause means that most retaining walls have to be designed to Part 4 of the Ontario Building Code by a qualified engineer. A retaining wall would also require a geotechnical investigation by a qualified engineer. Replacing a retaining wall will require multiple engineers and can be a significant task. Furthermore, since retaining walls are generally constructed near property lines a detailed cadastral/land survey may also be required.
There are many options for retaining wall construction and factors such as weight of the retained soil and weight of any vehicles above will govern the design.. Gravity retaining walls rely on their weight to hold back soil, most of the time theres are large concrete walls or cyclopean stone masonry. Retaining walls get a little more efficient when you design a reinforced concrete wall to hold back soil.
There are also pre-cast concrete blocks that are light weight and easy to install. The blocks assemble similar to lego and use a combination of tie backs and their weight to retain soils. The blocks can be cast to look like stone.
At IN Engineering our preferred option when it comes to retaining walls are pre-cast concrete block walls. They are quick and easy to install (saving the owner money) and they are also aesthetically pleasing. The design of these structures is also relatively simple. Lastly, with multiple suppliers in the area these walls are supporting local companies.
Earthship Engineering - Tire Retaining Walls | IN Engineering
December 11, 2018 @ 5:15 pm
[…] the maximum allowable height is increased to 4.4 feet or 1.3 meters. This barely qualifies as a retaining wall under the Ontario Building […]
Earthship Engineering - Tire Retaining Walls - IN Engineering & Surveying
March 31, 2020 @ 4:00 pm
[…] the maximum allowable height is increased to 4.4 feet or 1.3 meters. This barely qualifies as a retaining wall under the Ontario Building […]
June 13, 2020 @ 9:39 am
My residential neighbour is considering installing an 8’ high gravity retaining wall along their side of the property line between our houses. They are below my house and this wall will undercut the footings of my sunroom by 5’. They and the contractor they’ve been talking to interpret that section of the building code as not being applicable to this wall.
For my own peace of mind, I have offered to pay for the engineering review, regardless of whether a permit is required, to simply be confident the wall is built correctly. They are in a hurry and don’t want to wait for such a review. I suspect the only way I can press the issue is if a permit is actually required.
I called the city and they said per Ontario Building Code, a permit is required. Perhaps even they are mistaken.
I’d greatly appreciate if you could clarify your interpretation of the code as to whether an engineered design is in fact required for this case.
Thanks
September 8, 2020 @ 1:11 am
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June 4, 2024 @ 5:47 am
I appreciate knowing retaining walls play a crucial role in landscape management by controlling erosion and creating usable land. How do retaining walls contribute to effective landscape management?