Foundation Parging: Protecting Your Home's Below-Grade Exterior

Exterior Renovation Services

Parging — the cement coating applied to exposed foundation walls — protects against moisture, pests, and freeze-thaw damage, but requires correct application and maintenance to remain effective.

Parging serves as a first-line moisture barrier on the above-grade portion of foundation walls. It fills the porous texture of block or poured concrete, reducing water absorption, and provides a smooth, paintable surface for visual finishing.

Planning Your Project

Parged foundations are common on homes built in the 1950s through 1990s in Kitchener-Waterloo. Original parging, if not maintained, begins to crack and delaminate within 20 to 30 years as moisture cycles through the material. Delaminated parging traps water between itself and the foundation, accelerating the freeze-thaw damage it was meant to prevent.

Before re-parging, all loose or delaminated sections must be removed completely. Attempting to apply new parging over failing old material results in a repair that peels away within 1 to 2 seasons, carrying the fresh material with it.

Working With D&D Exterior Finishing

Correct parging thickness is 12 to 20 mm, applied in two coats if necessary. The scratch coat bonds to the masonry and is scored before full curing; the finish coat provides the smooth or textured surface. Each coat must cure at appropriate temperatures — parging should never be applied in temperatures below 5°C or during frost conditions.

Elastomeric parging products have improved significantly over traditional mixes. Elastomeric coatings flex with thermal movement rather than cracking rigidly, providing longer service life in Ontario's climate. They're available in multiple colours and finishes and can be applied over existing clean, sound parging as a maintenance coat.