Over time, mortar deteriorates and becomes a powder. The powder falls out. It looks scary when you touch a foundation and see the grey-white powder fall to the floor. It is normal aging; you can prevent trouble by repointing. The trouble begins when enough mortar is gone and the bricks are not supported enough to hold the weight of the house. Then the bricks will move, or crack. If enough bricks or stones move in a foundation, it will eventually become a structural issue. Repointing before the wall loses integrity is the key.
We see foundations with wavy lines of brick or loose stone frequently in these old buildings. If the house is still sitting straight, repointing will fix it. If that foundation is not fully repointed, the brick or stone will keep moving until the foundation fails. When this happens, the floors sink toward the outside of the house.
On a chimney, if mortar washes away enough to make a brick loose, it can fall off the roof or into the chimney. Either is bad news. A falling brick can damage the neighbor’s house or hurt a person or animal in its path. A brick that falls into a chimney can block the flue and cause smoke and carbon monoxide to get into your basement. If you are home when a brick falls in, you’ll hear it. Otherwise, you’ll hear your CO detector.
On a brick exterior wall, the brick is part of the look of the property. Therefore, keeping the bricks pointed is both a structural and aesthetic issue. Wavy lines of brick would make this condo look shabby. Note how one association fully repointed, the other did areas that needed it most. (The repointed areas show more white than the areas where the mortar is more weathered.)
How do you know when a brick or stone wall needs repointing?
If the mortar is getting powdery, repointing is in order. One of the good things about repointing is that you can do a small area, as needed. The way to do it is to scrape the powdery stuff out, wet down the wall, and put new mortar in. It’s not hard. But, it is slow work. Bob Villa explains it well.
So, if your home inspector told you that your foundation needs repointing, get to it!