What is the average estimate for parging both sides of a foundation wall in Ottawa?

Parging a foundation wall on both the interior and exterior sides is a common project in Ottawa, where older homes often have poured concrete or block foundations that need cosmetic and protective treatment. The two sides serve very different purposes, so let's break down the costs and considerations for each.

Cost Breakdown for Two-Sided Foundation Parging

For a typical Ottawa home with a foundation perimeter of 120–160 linear feet and walls 7–8 feet tall, here's what to expect:

Exterior foundation parging (above grade):

• Exposed height is typically 1–3 feet above grade- Coverage area: 150–400 sq ft- Cost: $1,500–$3,500 ($4–$8 per sq ft installed)

Interior foundation parging (full height):

• Full wall height, typically 7–8 feet- Coverage area: 900–1,200 sq ft- Cost: $2,500–$5,500 ($3–$5 per sq ft installed)

Both sides combined: $4,000–$9,000

Interior parging is cheaper per square foot because there's no excavation required and access is straightforward—though it does require the basement to be cleared of stored items along the walls.

What significantly affects the price:

Exterior excavation: If the exterior parging extends below grade (recommended for waterproofing), excavation costs add $2,000–$6,000 to the project. This involves digging down to the footing, parging the full exterior wall, applying a waterproofing membrane, and backfilling. For Ottawa homes in areas like Gloucester, Nepean, or Orleans where clay-heavy soils hold moisture against the foundation, this comprehensive approach is worth the investment.

Surface condition: Crumbling, deteriorated block or concrete needs repair before parging. Filling voids, re-pointing mortar joints on block walls, and applying bonding agents adds $500–$1,500 depending on condition. Many Ottawa foundations from the 1950s through 1970s have significant surface deterioration from decades of freeze-thaw exposure.

Material choice:

• Standard Portland cement parge: Most common, $3–$5/sq ft- Polymer-modified parge coat: Better flexibility and adhesion, $5–$8/sq ft- Fibre-reinforced parge: Best crack resistance for Ottawa's thermal movement, $6–$9/sq ft

Ottawa climate considerations: Foundation parging in Ottawa takes more punishment than almost anywhere in Canada. The combination of deep frost penetration (Ottawa's frost depth is 4–5 feet), aggressive freeze-thaw cycling, and road salt exposure means that cheap parging jobs often fail within 3–5 years. Investing in a polymer-modified or fibre-reinforced product adds 30–50% to the material cost but typically doubles the service life.

The Ontario Building Code requires foundation walls to be protected against moisture penetration below grade. While parging alone doesn't satisfy the waterproofing requirement (you also need a membrane or damp-proofing coating on the exterior), it's an important component of the overall system. Any contractor should be able to explain how the parging integrates with your foundation's waterproofing strategy. Get at least three written quotes that specify the product being used, the number of coats, and the expected thickness.

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• Justyn Rook Contracting
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