What Is Foundation Parging?
Parging is the cement-based coat on the exposed part of your foundation, the band between the soil and the brick or siding. It protects concrete block and poured concrete from weather, splash and salt, and it gives the base of the house a finished look.
In Toronto, parging takes a beating. Snow piles against it, de-icing salt splashes onto it and dozens of freeze-thaw cycles each winter work on any moisture behind it. When parging fails, it cracks, sounds hollow when tapped and eventually falls off in sheets, exposing the block underneath.
Why Most Parging Fails in Two Winters
The most common failure we see is freeze-thaw delamination. Parging was troweled over a wall that was damp, dusty or coated in old failing parging. There was no proper bond, so water got behind the coat, froze and pushed it off.
| Cause of failure | What it looks like | Our fix |
|---|---|---|
| Applied over damp substrate | Large sheets letting go | Infrared moisture scan first, fix the moisture source |
| No bonding layer | Hollow sound, flaking edges | Acrylic bonding membrane on prepared substrate |
| Skim over old parging | Cracks following old patches | Full strip to sound block or concrete |
| Single thin coat | Hairline cracking, wear-through | Scratch coat plus finish coat, mesh where needed |
| Poor grade transition | Damage at soil line | Detail the grade transition to shed water |
Our Parging Method
- Infrared moisture detection. We scan every wall before quoting. If there is active moisture, from a crack, poor grading or hydrostatic pressure in the soil, we tell you and fix the source first.
- Strip. All loose and hollow parging comes off to sound substrate.
- Repair and bond. Cracks and voids are patched and an acrylic bonding membrane goes on.
- Scratch coat. A first coat of Portland cement-sand mix, with fiberglass mesh embedded where the wall is cracked or uneven, scored to take the next coat.
- Finish coat. Hand-smoothed, sponge or textured, cured and protected from frost.
Parging is not waterproofing
Parging protects the exposed foundation. It will not stop water pushing through a cracked wall below grade. If you have basement leaks, we check for foundation cracks and wider foundation problems at the same visit.
Commercial and Multi-Unit Parging Programs
Property managers often have the same parging failing across several sides of a building or several buildings. We survey the whole envelope, prioritize the worst walls and phase work so tenants keep access to entrances and parking. WSIB and $5M liability certificates come before the scaffold, and water-damaged sections can be billed directly to your insurer.
Parging and Stucco
Parging and stucco use similar materials. If the walls above your foundation are stucco and are cracking too, see our stucco page. We often match the parging finish to stucco above so the house looks consistent.
Parging is one of the most requested services at our Toronto masonry company, and we inspect the foundation behind it before quoting.
