What Does Concrete Sealing Do?
Sealing is the cheapest thing you can do to concrete and the one with the best return. At $1.50 to $3 per square foot, resealing a driveway every few years costs a fraction of what a replacement costs at $10 to $16, and it is the single largest factor in whether a GTA slab reaches thirty years or starts failing at twelve.
The mechanism is straightforward. Concrete is porous. In Toronto, road salt dissolves into meltwater, that chloride-laden water soaks into the surface, and then it freezes. Water expands roughly nine percent when it freezes, and inside a confined pore that expansion generates enough pressure to break the concrete apart from within. Repeat it a hundred times a winter and the surface scales away layer by layer. Chloride also reaches embedded rebar and corrodes it, and corroding steel expands enough to split concrete from the inside.
Sealers interrupt that cycle by keeping the water and the chloride out. Which sealer depends entirely on the surface and its exposure, and this is where most sealing jobs go wrong.
What’s Included
- Surface assessment: age, porosity, existing sealer and exposure
- Cleaning, efflorescence removal and stripping of failed sealer
- Drying time before application
- Product selection matched to the surface
- Even application with a maintained wet edge
- Second coat on high-exposure areas where specified
- Slip-resistant additive on walkways, steps and pool decks
- Cure time and a written reseal schedule
The Four Product Types
Silane-siloxane penetrating sealers soak into the concrete and react inside the pore structure. They form no film, so there is nothing to peel and no change to how the surface looks or grips. They block chloride while still letting the slab breathe. This is our default for driveways, walkways and any plain exterior concrete.
Acrylic sealers form a thin film on the surface. They darken and enrich colour, giving the wet-look finish that stamped and exposed aggregate work is usually sold with. They protect well but need reapplication more often and can be slick when wet, so a slip additive goes in as standard.
Lithium-silicate densifiers react with free lime inside the concrete to form additional binder. They harden the surface and reduce porosity rather than coating it. Standard on interior floors and used alongside polishing.
Below-grade waterproof coatings are a different class entirely, applied to the outside face of foundation walls before membrane and backfill. They are part of foundation work rather than surface maintenance.
Common Problems We Solve
Driveways Scaling After Three Winters
Almost always an unsealed slab, sometimes combined with concrete that was not properly air entrained. Sealing what is left slows further damage, though surface already lost has to be resurfaced.
Stamped Concrete Losing Its Colour
The accent colour on stamped work lives in the top surface, and without a maintained sealer it wears and fades. Resealing every two to three years is what keeps decorative concrete looking the way it did on day one.
Efflorescence Returning
That white powdery bloom is free lime carried out by moisture moving through concrete. Washing it off and sealing reduces the moisture movement that causes it.
Failed Previous Sealer
Peeling, hazy or blotchy sealer is usually a film-former applied over a damp or dirty surface, or applied too thickly. It has to be stripped before anything new goes down, which we quote as part of the work.
How Much Does Sealing Cost in Toronto?
Sealing runs $1.50 to $3 per square foot. Drivers:
- Product. Penetrating sealers cost less per foot than premium acrylics or densifiers.
- Number of coats. High-exposure areas benefit from two.
- Preparation. Stripping failed sealer or removing heavy staining adds labour.
- Surface texture. Exposed aggregate and stamped surfaces use more product than smooth slabs.
- Area. Larger areas are more efficient per square foot.
Timing Matters
New concrete needs about 28 days to cure before sealing, and any curing compound needs to have worn off or been removed. Sealing early traps moisture and produces hazing or outright failure.
Weather matters too. The surface must be genuinely dry, temperatures need to be within the product range, and rain within the cure window ruins the application. In the GTA that generally means late spring through early autumn for exterior work.
If you call us in November about sealing a driveway, we will most likely tell you to wait until spring. That is not us turning down work, it is the difference between a sealer that performs and one you pay for twice.
Send us the surface type, its approximate area and its age, and we will come back with a written published-rate quote inside two hours.
