Brick cracks. All brick, everywhere, eventually. The question is never whether your house has a crack in it, it is which kind you are looking at.
The one worth paying attention to in North Texas is the stair-step crack: a diagonal line that climbs through the mortar joints, going across then up, across then up, like a set of stairs. Here is how to read one.
Why they step
Mortar is weaker than brick. When one part of a wall moves down relative to another, the wall does not tear straight through the middle of the bricks. It finds the path of least resistance, which is the mortar, so the crack travels sideways along a bed joint, then up a head joint, then sideways again.
That staircase pattern is the wall telling you which direction the movement went. The crack generally gets wider toward the end that dropped.
Where they show up
Almost always at a weak point in the wall:
- Corners of the house, especially the corner over the driest soil.
- Above and below windows, where the wall is already interrupted.
- Above doorways and garage openings.
- Where an addition meets the original structure, because the two were built at different times on soil that has settled differently.
Which cracks are worth worrying about
A rough guide, and it is only a guide:
- Hairline, vertical, in the mortar only. Ordinary. Mortar shrinks as it cures and continues to move slightly with temperature. Most houses have some.
- Thin stair-step, under about the width of a credit card. Worth photographing and watching. Not urgent.
- Stair-step wider than a pencil, or one that is clearly wider at one end. Worth having measured.
- Cracks running through the bricks themselves rather than around them. That takes more force than mortar cracking and deserves a look.
- A crack you can see daylight through, or where the wall is no longer flat. Call someone.
How to tell whether it is still moving
This is the part most people skip, and it is the most useful thing you can do.
Take a photo with something for scale in the frame, a coin or a tape measure, and note the date. Then mark the ends of the crack with a pencil line so you can see later whether it has grown past the mark. Check again after the next big weather swing, so after a long dry spell or after a week of heavy rain.
A crack that has not moved in a year is a record of something that already happened. A crack that is visibly longer or wider than your photo is an active problem, and that distinction changes what you should do about it.
What causes it here
In Dallas it is nearly always the clay. It swells when wet and shrinks when dry, and the shrinking pulls support out from under one part of the house. The corner over the driest ground drops, the brick above it cannot follow, and the wall cracks.
Which is why the fix is usually two things, not one. Support the part that dropped, and stop the soil from swinging so far between wet and dry in the first place.
What to do about it
If the crack is hairline and vertical, nothing. Point the mortar if it bothers you.
If it is stepping, widening, or you have other signs alongside it — doors sticking, sloping floors, gaps at the baseboards — get elevations measured. We do that for free, and it tells you how far the house has actually moved rather than how bad the crack looks.
If something has moved, the repair is usually foundation repair or house leveling, depending on whether one area settled or the slab moved more broadly. And in most cases we will also talk to you about drainage, because piers hold the house up but drainage is what stops the conditions coming back.
One thing not to do
Do not fill the crack and repaint before you know whether it is active. Patching an active crack does not stop it, it just removes the evidence, and the next person to look at your house has no idea how long it has been moving or how fast.
Photograph it first. Then patch it if you want to.
Common questions
Are all stair-step cracks serious?
No. A thin one that has not changed in a year is a record of movement that already finished. Width and whether it is still growing matter more than the shape.
How wide is too wide?
As a rough guide, wider than a pencil is worth having measured, particularly if the crack is noticeably wider at one end than the other.
Should I fill the crack?
Not until you know whether it is still moving. Photograph it with something for scale, mark the ends, and check again after the next big wet or dry spell.
Does a cracked brick wall mean my foundation is failing?
Not on its own. Brick cracks for several reasons. It becomes a foundation question when it appears alongside sticking doors, sloping floors or gaps at the baseboards.
