Restoration Register

Heritage plaster restoration in Ontario

The default answer to a cracked or sagging plaster ceiling in Ontario is a tear-out and drywall. It is almost always the wrong answer. A ceiling whose keys have broken off the lath can usually be re-secured from below with washers and adhesive, saving the ceiling and the cornice attached to it.

Heritage plaster work is flat work and ornament. Flat work is three-coat lime plaster on wood lath: re-keying loose fields, patching to original thickness so the surface stays flush, and finishing in a compatible mix rather than a hard modern skim that will craze along the boundary. Ornament is run cornices, ceiling medallions, corbels and enrichments, reproduced either by running a profile in place with a zinc template or by casting from a mould taken off surviving work. Only eleven specialists cover the province and seven of them are in the GTA, so outside Toronto this is a trade you book around rather than schedule at will.

What to ask before you hire

  1. Can this ceiling be re-keyed rather than replaced? Ask before anyone prices a tear-out.
  2. Will you run the cornice in place, or cast it? Both are legitimate. Stock polyurethane cornice from a catalogue is not restoration.
  3. What mix will you patch and finish with? A hard modern skim over soft lime plaster cracks along the joint within a couple of seasons.
Grant funding

Interior plaster is eligible where the designation by-law protects interior features, which many do not. Read the by-law, or ask municipal heritage staff what your designation actually covers, before planning the work around a grant.

Across Ontario

Region pages

Related heritage trades

Get quotes for your project

Tell us about the job and we will pass it to up to three listed heritage trades who work in your area. It is free and there is no obligation.

All heritage service pages · Grants by municipality