Repairing an old limestone house wall in Ottawa's Lowertown?

Repairing the natural stone walls of a limestone house has too few published prices to quote a range, so ask each mason for a written quote that breaks out the scope in detail.

What drives the cost and the approach is the condition of the stone itself and the mortar joints. A mason at the wall can tell you which stones need to be reset or replaced, which joints need to be raked out and repointed, and whether any section raises a structural question that needs to go to the City first.

Mortar choice matters here. For historic walls in its district, the Centretown and Minto Park Heritage Conservation District plan states that lime-based mortar should be used when repointing historic brick and masonry, because cement mortar prevents moisture from escaping through the mortar and causes damage. It also says that using a mason experienced in lime-based mortar is encouraged. If your property is designated or sits within a heritage conservation district, check whether your district's plan has its own guidelines, or ask the City's heritage staff. Either way, ask the mason what mortar they propose and why.

A fair written quote for this job should cover:

• which stones are to be repaired, reset or replaced, and where matching limestone comes from
• the full extent of repointing, with mortar type, colour match and joint profile specified
• how joints will be cut out and how silica dust will be controlled on site
• scaffolding or lift costs if upper courses are involved
• removal and disposal of debris
• who is responsible for asking the City about permits if any section of wall is being rebuilt or structurally altered

One thing worth pinning down before you sign: ask the mason to describe, in writing, exactly how they will match the replacement stone and mortar to what is already on the wall.