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.

1 Comment

  1. […] 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 […]

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