Why is my mortar crumbling out of the joints in Kanata?

Crumbling mortar joints have more than one possible cause, and a mason looking at your wall is the only one who can say what is driving it in your case.

NRC building digest CBD-123 notes that "shelling of the mortar surface and general crumbling or powdering of mortar are evidence of advanced deterioration due to freezing," so frost cycling is one mechanism worth ruling in or out, but it is not the only one.

A few things that shape what the repair involves:

• How deep the deterioration goes. Shallow surface crumbling and joints that are hollow several centimetres back are different jobs.
• The mortar type already in the wall. Ask what is in the wall now and what the mason proposes; the Ontario Building Code (9.20.3.1.(1)) requires mortar to conform to CSA A179.
• How much of the wall is affected. A small section and a full facade are priced differently.
• Height and access. Upper courses need scaffolding or a lift, which adds to the scope.

For a written quote, ask for the area of wall being repointed, how joints will be cut out and to what depth, the mortar type and colour match, how silica dust will be controlled during cutting, what brick replacement is included if any units are damaged, and what cleanup and disposal cover.

Start with a mason at the wall, because the repair scope, which mortar to use and whether any units need replacing all depend on what they find when they probe the joints in person.