Our backyard in Scarborough slopes significantly — about 8 feet of grade change over 25 feet. The previous timber retaining wall (installed circa 1992) was leaning badly by 2023. This is the story of replacing it.
First surprise — the TRCA: Our property is within 30m of a Highland Creek tributary. This means the Toronto and Region Conservation Authority (TRCA) has permitting jurisdiction in addition to the city. We needed both a TRCA permit and a City of Toronto building permit. The TRCA process added $1,800 to our costs (application fee + consultant report) and 8 weeks to our timeline.
Engineering requirement: Our wall is 1.6m high at its tallest point — over Toronto’s 1.0m threshold that requires professional engineering involvement. We hired a structural engineer to design the wall and provide stamped drawings: $2,400.
The wall we built: Armourstone (large irregular granite boulders, 0.5–2 ton each). The engineer specified minimum 500mm embedment below grade for the base course, geotextile fabric behind the full wall height, and granular drainage fill behind the wall.
TRCA conditions: We had to maintain a 5m vegetated buffer from the top of the bank. Our wall actually improved the ecological situation versus the failing timber wall, which helped the application.
Cost breakdown:
- Structural engineer: $2,400
- TRCA permit and application consultant: $1,800
- City of Toronto building permit: $440
- Armourstone supply (machine-placed, 38 linear feet): $14,200
- Excavation and grading: $3,400
- Drainage aggregate and geotextile: $1,100
- Restoration planting (TRCA requirement): $800
- Total: $24,140
Not cheap. But the yard is now functional and the wall will outlast the house.