Diagnosis

Cracked Brick Veneer or a Structural Crack? How to Tell

Not every crack in a brick wall means the house is moving. Here is how to read one, which patterns are cosmetic, and the point where guessing should stop.

Two different problems that leave similar marks

A crack in brick sets off the same reaction in most people, and the reaction is usually out of proportion to the cause. Brick is rigid and everything around it moves, so cracking is normal behavior for the material. What matters is which part of the house moved and how far.

There are really two questions. Did the brick move on its own, or did the thing holding the brick up move? The first is a masonry repair. The second is a foundation question, and no amount of tuckpointing fixes it.

First, work out what your wall actually is

Almost every brick house built in Rutherford County since the 1960s is brick veneer over a wood frame. The brick is a single wythe hung on the outside of the structure, tied back with metal ties, carrying nothing but itself. Smyrna, La Vergne, Blackman, and the newer Murfreesboro subdivisions are veneer almost without exception.

Older houses near the square and out in the county can be solid masonry, two or more wythes thick, where the brick genuinely holds the building up. The distinction changes what a crack means, so establish it before anything else.

You can usually tell from the outside. Look at a window or door jamb and see how thick the wall reads. Look along the base of the wall for weep holes, small open joints every few feet, which only exist on veneer. Look for header courses, bricks turned end out at intervals, which usually mean solid masonry.

Five things to read in a crack

Take a photo straight on with something for scale, a quarter or a tape, then work through these. Any one of them alone proves little. Together they usually point one direction.

Width is the crude first filter. A crack you cannot get a business card into is a different animal from one you can slide a pencil into. Path matters more. A crack that runs through the mortar joints only is following the weakest line, which is what mortar is supposed to do. A crack that splits brick faces straight through has more force behind it.

• Width, measured at the widest point, not at the ends
• Path: joints only, or straight through the brick units
• Direction: vertical, horizontal, or diagonal stair step
• Offset: whether the two sides sit flush or one has pushed out of plane
• Movement: whether it is wider, longer, or the same as it was last year

Cracks that are usually the veneer alone

Brick expands slightly and permanently over its first years, and it moves with temperature every day. On a long veneer wall with no expansion joint, that movement has to go somewhere, and it usually goes into a crack near a corner or an opening.

The patterns below are common, they are repairable by a mason, and on their own they do not mean the house is settling.

• Hairline stepping in the mortar joints at the corner of a window or door
• A short vertical crack near a building corner on a long uninterrupted wall
• Fine cracking directly under a sill, where the brick is the least supported
• A crack that follows a steel lintel over an opening, which is often rust jacking rather than settlement
• Isolated cracked units around a wall penetration or an old fastener
• Cracking that has been the same width in photos for several years

Cracks that need a structural opinion

Clay soil is the driver here. Rutherford County clay shrinks in a dry August and swells with the winter and spring rain, and that cycle works on footings year after year. Where the soil under one part of the house behaves differently, the house tilts slightly and the brick records it.

The list below is not a panic list. It is a call-someone list. Several of these have simple causes, but none of them should be diagnosed from the ground by a homeowner or patched by a handyman.

• A crack wider than about a quarter inch, or one that tapers open toward the top or bottom
• Any crack where one side has moved out of plane with the other
• A long diagonal stair step running from a corner up toward the roofline
• A horizontal crack running a long distance through the wall
• Brick cracking that appears alongside doors sticking, windows binding, or new drywall cracks inside
• A crack that has visibly grown in the last six to twelve months
• Any of the above on a solid masonry wall rather than a veneer

Monitor properly instead of guessing

Most cracks are best answered with time rather than opinion. The trick is measuring in a way you can actually compare later, which almost nobody does.

Mark both ends of the crack with a pencil line and the date. Photograph it straight on with a coin taped next to it. Write the measured width at the widest point on a note in the photo. Then do it again in three months, and again after a wet spring and a dry late summer, since that is the full clay cycle here.

A crack that stays put across a whole seasonal swing is telling you something useful. One that opens every August and closes every March is telling you something different, and one that only ever grows is telling you the most important thing of all.

When to stop guessing, and who to call

Call a licensed structural engineer, not a repair contractor, when anything on the second list applies. An engineer sells an opinion rather than a repair, which is exactly why the opinion is worth paying for. You get a written assessment you can hand to a mason, a foundation contractor, an insurer, or a buyer.

A mason is the right first call when the wall is veneer, the crack follows joints, nothing is out of plane, and the pattern has been stable. That work is cutting out the damaged section, replacing units where needed, matching mortar to the existing joint, and often adding or restoring an expansion joint so the same movement has somewhere to go next time.

Either way, deal with the water first. A downspout dumping at a corner will keep the soil under that corner in a permanent wet and dry cycle, and it undoes any repair you make above it.

Related services: Brick Masonry · Stone Masonry