Many west siders will be familiar with this, reputed to be  the oldest house in Ottawa:

It is located a half block east of the Westboro Loblaws.

Work has been going on for a while to stabilize and repair the structure. Like a lot of building restoration work, or art restoration, much effort goes into undoing the previous version of restoration.

In this case, the previous work involved adding a smooth coat of mortar between the stones. Alas, that mortar dried hard and waterproof. This trapped moisture between the stone inside the wall, which then liquified/eroded the sand-lime mixture inside the wall, causing it to become unstable.

This round of renovations, by Northside Historic Masonry, involved pumping grout into the centre of the stone walls, to glue everything together. Then the exterior old mortar was removed, to be replaced by a more porous high-lime mortar. This new finish is being kept further back from the face of the stones, so the wall will have more texture.

Only the northeast corner is done now, as that area needed structural repairs to the five-foot-thick stone foundation (the wall is “only” three feet thick at its top). Next year, the rest of the house will be done, chipping out the old mortar, adding grout, then remortaring. ,

If you stand on the sidewalk today, you can see the difference between the old wall, which brushed a lot of mortar onto the face of the stones, with the new. In the picture below, the new section hasn’t yet received its final mortar coat, but the picture will help you pick out the new area from the old when you see the building.