When is a crack in parging nothing to worry about?

Fine hairline cracks that are not growing are usually cosmetic. They come from the coat shrinking as it cures and from small seasonal movement, and they let very little water in. A crack is worth a closer look when it widens over a season, reopens in the same line after a patch, runs in a stepped pattern along block joints, or has one side sitting proud of the other. Those signs point to movement in the wall behind the coating, which a new coat will not fix. A simple test is to mark the ends of the crack with a pencil and date it, then check again after the next freeze and thaw. If the crack has grown, see our foundation crack repair page or book a free inspection.