What we build
We build poured concrete retaining walls that hold back a grade change, landscape and garden walls, and low walls that frame a driveway, walkway or a new set of front steps. We also do concrete wall repair on existing landscape and retaining walls, including cracked caps, spalled faces and broken corners, as long as the wall isn’t moving. A wall that’s leaning or sliding needs rebuilding, not patching.
When a retaining wall needs a permit
The City of Ottawa’s Landscaping Education Guide says retaining walls more than 1 m in exposed height need a building permit when they’re next to public property, next to access to a building, or on privately owned land open to the public. The guide is advisory, so we confirm each site with the City. Other City rules apply too:
- The City’s advisory on landscaping materials that provide access to a building says landscape structures over 1 m need a Part 4 (engineered) design. They also may not be attached to the foundation unless an Ontario professional engineer designs the connection.
- Permanent structures such as retaining walls are often not allowed in the City right of way. Part of your front yard may be right of way, and it may be wider than you think.
- You may not change your lot’s approved grading or redirect water onto a neighbour, which matters when a wall creates a new level.
- Hardscaping contractors who build retaining walls must be licensed by the City. Ask any contractor for their licence.
Choosing the right concrete class
Walls see different exposure from a driveway, and CSA A23.1 sets the concrete class to match:
| Wall situation | CSA class | Min. strength | Max. water-cement ratio | Air |
|---|---|---|---|---|
| Catches salt spray or snowbanks (beside a driveway, walk or steps) | C-2 | 32 MPa | 0.45 | 5–8 % |
| Freeze-thaw, not saturated, no salt | F-2 | 25 MPa | 0.55 | Category 2 |
| No freeze-thaw or salt exposure | N | Per design | Per design | — |
CSA’s own examples for F-2 are exterior walls and columns. In practice, any wall within reach of a plough, a shovel or a snowbank in Ottawa gets salted, so we pour C-2 wherever there’s doubt. The MPa guide explains the difference.
Drainage is the wall’s real job
Water is what pushes walls over. Soil that can’t drain gets heavier against the back of the wall. When it freezes, frost-susceptible soils heave, and the NRC has documented long-term settlement on Ottawa’s sensitive marine clays. A wall built without drainage is fighting all three at once.
Our approach on every retaining wall:
- Free-draining stone behind the wall instead of native clay backfill.
- A perforated drain at the base, led to daylight or an approved outlet where the grading allows.
- Weep openings where the design calls for them, so water can’t build up behind the face.
- A footing sized for the wall’s height, the soil and what sits above it, such as a driveway or a slope. Walls over 1 m get an engineered design where the City requires one.
- Grading at the top that sheds surface water away from the wall rather than into it.
How a wall project runs
- Site visit, covering the height, soil, drainage, property line and what the wall supports.
- Permit check, including the City right of way and whether an engineered design is needed.
- A free utility locate before excavation.
- Excavation and footing.
- Forming and reinforcement.
- Pour and cure, with at least 7 days of curing.
- Drainage, backfill and grading.
See how concrete is poured and our process.
What a concrete wall costs
Concrete and retaining walls run about $45–$120 per sq ft of wall face in Ottawa. Height, footing size, drainage, access and any engineering move the number most. See the concrete cost guide.