How much does it cost to parge a poured concrete retaining wall that's about 30 feet long?

Parging a 30-foot poured concrete retaining wall in the GTA typically costs $1,500 to $4,500, depending on the height of the wall, its condition, accessibility, and whether you choose traditional Portland cement or polymer-modified parging. For a standard residential retaining wall between 3 and 5 feet tall, you are looking at roughly 90 to 150 square feet of surface area on the exposed face, which at $12 to $18 per square foot for polymer-modified parging puts the project squarely in that range.

Retaining walls present different challenges than foundation walls, and those differences affect the cost. The exposed face of a retaining wall takes a beating — it faces direct rain, wind-driven snow, salt splash from adjacent walkways or driveways, and full sun exposure on south- and west-facing walls. Unlike foundation walls where the bottom portion is protected by soil, a retaining wall's entire face is exposed to the elements. This constant exposure means polymer-modified parging is strongly recommended over traditional Portland cement parging for retaining walls in the GTA. The polymer additives provide the flexibility and freeze-thaw resistance needed to survive 50-plus freeze-thaw cycles per winter on a fully exposed surface.

The condition of the existing concrete surface significantly affects the cost. A relatively new, clean poured concrete wall in good condition needs only cleaning, bonding agent, and one or two coats of parging — straightforward work at the lower end of the price range. An older wall with form tie holes, honeycombed concrete, surface scaling, or existing failed parging that needs removal requires more extensive surface preparation including filling voids, installing wire mesh reinforcement over damaged areas, and potentially two full coats of parging. Surface preparation on a deteriorated wall can add $500 to $1,500 to the project.

If the retaining wall has both a front face and a visible cap, add $5 to $10 per linear foot for parging or capping the top surface. A properly finished cap with a slight slope away from the retained soil side prevents water from pooling on top of the wall and seeping down behind the parging. Some homeowners opt for a precast concrete cap or natural stone cap instead of parging the top, which costs $15 to $30 per linear foot but provides a more finished look and better long-term water shedding.

For retaining walls that also serve as a garden border or are adjacent to planting beds, ensure the parging extends at least 4 inches below the soil line on the exposed side, and consider applying a penetrating concrete sealer ($3 to $7 per square foot) to protect the parging from constant soil moisture contact. The back side of the retaining wall — the side holding back soil — should have waterproofing membrane and drainage gravel rather than parging, since that side is under constant hydrostatic pressure from soil moisture.

Schedule the work during the GTA's safe parging window, mid-April through mid-October, and ensure the contractor allows for proper curing — keeping the fresh parging moist for three to five days after application. Get three quotes from masonry contractors with WSIB coverage, and ask whether the quote includes surface preparation, bonding agent, and cap finishing.