How much do Toronto contractors charge to apply a waterproof coating over existing parging?

Applying a waterproof coating over existing parging in the GTA costs $3 to $7 per square foot for a penetrating concrete sealer, or $5 to $12 per square foot for an elastomeric waterproof coating, depending on the product type and the condition of the existing parging. For a typical Toronto home with 150 to 250 square feet of exposed foundation parging, that translates to $450 to $1,750 for a penetrating sealer or $750 to $3,000 for an elastomeric coating.

The critical distinction is between the two main types of waterproof coatings, because they work very differently. Penetrating concrete sealers (silane or siloxane-based) soak into the parging surface and create a hydrophobic barrier within the material itself. They don't change the appearance of the parging, they allow moisture vapour to escape from inside the concrete (breathable), and they're excellent at repelling road salt and de-icing chemicals. A penetrating sealer is the right choice when the existing parging is in good condition — solid, well-bonded, with only minor hairline cracks — and you want to extend its lifespan by reducing water and salt absorption. Application is straightforward: clean the surface, let it dry, and apply the sealer with a brush, roller, or sprayer. One coat is usually sufficient, and the sealer lasts 5 to 10 years before reapplication is needed.

Elastomeric waterproof coatings are thick, rubberized paint-like products that form a continuous flexible membrane over the parging surface. They bridge hairline cracks up to 1 to 2mm, stretch with temperature cycling, and provide a visible protective layer that can be tinted or coloured. Products like Drylok, Xypex, or elastomeric masonry coatings fall into this category. They're the right choice when the parging has minor surface deterioration, fine cracking, or early-stage efflorescence that you want to seal and protect without re-parging. At $5 to $12 per square foot installed (two coats are typically required), they cost more than penetrating sealers but provide a more robust barrier.

Here's the important caveat that Toronto contractors will tell you upfront: no waterproof coating will fix failing parging. If the existing parging is delaminated (hollow-sounding when tapped), flaking in chunks, crumbling, or has cracks wider than 2 to 3mm, coating over it is a waste of money. The coating bonds to the parging surface, and if the parging itself is separating from the foundation, the coating comes off with it. Any reputable contractor will assess the condition of your existing parging before recommending a coating and will tell you honestly if sections need repair or replacement before coating makes sense.

Also understand that above-grade waterproof coatings are not the same as below-grade waterproofing. If water is entering your basement through the foundation walls below soil level, an above-grade coating on the exposed parging won't solve the problem. Below-grade waterproofing requires excavation to the footing, application of a liquid waterproofing membrane, installation of a dimpled drainage board, and often replacement of the weeping tile — a project costing $3,000 to $12,000 depending on linear footage and depth. Above-grade coatings protect the visible parging from rain, snow, and salt but don't address hydrostatic pressure from groundwater below grade.

For above-grade coating projects, get two to three quotes. Confirm WSIB coverage and ask what product the contractor uses and how many coats they apply. Toronto Parging can match you with waterproofing professionals through the Toronto Construction Network for free.