What's Included
The stucco repair process for Markham homes
Sounding the stucco for hollow spots
Cracks show where stucco has failed at the surface, but loose stucco can look perfectly sound. Preservation Brief 22 describes the test plainly. Areas that have lost their key echo with a hollow sound when tapped gently with a wooden or acrylic hammer or mallet, and the testing is done systematically on every side.
Our specialists sound each face of your Markham chimney that can be reached safely, mark the hollow areas and measure them. That map sets the size of the repair on the estimate, so a patch is never sized to the visible crack while loose stucco sits just beyond its edge.
Preparing brick so new stucco bonds
Stucco applied straight to masonry needs something to grip. Preservation Brief 22 describes raking out brick or stone mortar joints to a depth of about 5/8 inch where needed to ensure a good bond, and it notes that the irregular masonry or a scratched, roughened face provides the key.
On a brick chimney in Markham that has lost its stucco in places, our masons clean the exposed brick, rake soft joints where the bond calls for it and check the brick itself before new stucco goes on. Any loose brick found under the stucco is priced as a masonry repair on its own line.
A repair mix that suits the old stucco
A stucco repair mix should come close to the existing stucco in strength, density, porosity and water absorption, according to the International Masonry Institute. Preservation Brief 22 adds a warning. Rigid portland cement repairs placed on soft, lime-based stucco move differently and tend to crack.
Chimney stucco can be modern cement plaster, an older lime mix or a patchwork of past repairs. Our pros look at the existing finish on your Markham chimney before mixing, and they avoid a repair much harder than what surrounds it, since a patch that outlives the stucco beside it has simply moved the crack.
Painting stucco after the repair
Many stucco chimneys are painted, and the paint has to go back on after a repair. Preservation Brief 22 says the most important factor is that the new paint be compatible with any coating already on the surface, that loose or peeling paint be removed first, and it warns that latex paint will not stick to chalky or powdery areas.
Our crew scrapes loose paint around the repair on your Markham chimney, cleans the surface and recommends a coating that suits both the old paint and the new stucco. Oil-based paint needs new stucco to cure far longer, up to a year according to the brief, so the product choice also sets when the chimney can be painted.
