Restoration Register

Heritage masonry cleaning in Toronto and the GTA

Sandblasting a brick building is permanent damage sold as a cleaning service. It strips the fired outer skin of the brick and leaves the soft, porous body exposed to water, and every subsequent problem that building has for the rest of its life traces back to that one afternoon.

Correct heritage cleaning is the gentlest method that works, established by test patches on an inconspicuous area before anything else happens. In Toronto that usually means superheated low-pressure water systems, chemical poultices drawn against staining, and carefully selected proprietary cleaners, rather than abrasive blasting or a pressure washer at full trigger. What is being removed matters too: urban soiling and carbon crusts, biological growth on north elevations, efflorescence bleeding through from salts in the wall, graffiti, and paint applied over brick that was never meant to be painted. Paint removal in particular can pull the brick face with it if the wrong stripper is used, so the test patch is not a formality.

What to ask before you hire

  1. Will you do test patches first, and may I see them before you proceed? Any competent heritage cleaner offers this without being asked.
  2. What pressure, and what chemistry? Ask for the numbers and the product name. Abrasive blasting on historic brick is not an acceptable answer at any pressure.
  3. What are you going to do about the cause? Cleaning biological growth or efflorescence without fixing the water getting in means paying to do it twice.
Grant funding

Cleaning is eligible under Toronto's program as part of masonry conservation, and under the Oakville, Markham and Caledon programs. Some municipalities ask for a method statement, and the test patch documentation usually satisfies it.

Contractors on this page

Part of

All heritage service pages · Grants by municipality