Over the winter a large crack appeared, running across the mortar between a number of external bricks. The crack runs on a diagonal and includes a crack along a windowsill.

It appears that this mortar has been repaired previously.

We had an extremely cold winter, the worst in 20 years.

The house is 100+ years old.

Any thoughts on what would cause a crack of this nature? Any advice on how to fix the underlying issue?

crack in the mortar

crack in the mortar 2

2 Answers 2


I worked on a home that had this happen much more severely. The home was built on fill dirt and over the years one corner of this Washington DC townhome built in the 1920's sunk 5". To remedy it took the same thing that most likely will take to fix your issue.

In your case, if it is from the freezing of the ground, the dirt is expanding under the foundation, in essence lifting it up, then thawing out, and coming back down. The movement may be minute, but masonry does not get along with movement at all. Without a larger view of the home and other cracks elsewhere, this does not look like what is happening. What is seen in the picture to me looks like the wall under the window is dropping, not just cracking and separating. Checking the level of the floor inside that part of the house will confirm this, AND this depends on the direction that the floor joists run matters too. If they run parallel with the wall the window is in, you may not detect any drop in the floor.

The reason the wall would sink under the window is the foundation may be failing. Whether the freezing ground is lifting, or the window dropping, underpinning is the remedy. It is costly, and a company that does this type of work needs to be brought in to do it.

If this has been going on for the life of the home and has only dropped 1" or less, I would not jump into this type of repair just yet. If it opens up another 1/8" in the next 10 years, then the settling is consistent for the time the home has been standing, more or less.

  • I see what looks like 2, maybe 3 different color mortar in the joints in the close up photo when enlarged. Does that change your opinion on how soon one should act? Commented May 17, 2014 at 3:55
  • First thoughts, no. The house has been around for over 100 years, each repointing happened over that span as well. So doing the math, it would be a slow gradual settling. Only the homeowner could say if all the repointing has happened only recently and opened up again. As mentioned in the OP, if this has taken 20 years for this to occur, then it plays into my theory. After all that is what it can ever be anyway.
    – Jack
    Commented May 17, 2014 at 4:31
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    Bottom line, if it can be afforded, get it looked at by a local soils inspector, not by a contractor that does the work, 'cause he will say of course you need to do this or that, because it will be money in his pocket. So find somebody independent from a contractor. But getting it underpinned is a way to keep the cracks in check
    – Jack
    Commented May 17, 2014 at 4:36
  • This is a case of classic settling. Diagonal cracks from windows or lentils are so common on older structures. See them all the time. Jack is right on, if there is no displacement, or bricks coming loose, a simple repointing is probably your only reasonable fix. If internal trim, doors, windows etc are not effected, I would not get too excited. Commented May 17, 2014 at 10:08

That looks like earth or foundation settling. How to fix it depends on the cause.

If there is a large sinkhole under it, probably the best fix is to move elsewhere and abandon it.

If the soil moved because of water movement, some drainage work to prevent further erosion and then perhaps pumping in under pressure some sand or gravel to stabilize—or even reverse some of it.

If there is a nearby hillside, some work to stabilize the soil would help. If the soil is firm and bedrock is close, some pylons into bedrock would do the trick. If it is clay and nothing firm close underneath, the ultimate is to jack up the house, insert steel I-beams, and build a new foundation. For other types of soils, measures in between might work.

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