What is corner pop on a foundation?

Corner pop is a chunk of concrete breaking away at the outside corner of a slab, right where the brick sits on the foundation ledge. It looks alarming and it is usually cosmetic. Brick expands and contracts with temperature, and where it bonded to the concrete it drags that corner with it until the corner spalls off.

What corner pop looks like and where it happens on the house

Stand at a corner of a brick house on a slab and look at the bottom two feet of concrete. Corner pop shows up as a crack in the exposed slab edge right at the corner, usually with a wedge of concrete loose or already gone, as if somebody had knocked it off with a hammer. The chip runs a few inches across and stays shallow. The break faces out, away from the house, and the concrete behind it is sound. It happens on brick and stone veneer homes and almost nowhere else, because it takes a masonry wall sitting on a concrete ledge. It often turns up on more than one corner of the same house, which is itself a clue. Soil does not treat four corners the same way. A material wrapped around all four of them does.

Why the brick breaks the corner off the slab

The brick veneer sits on a ledge cast into the edge of the slab, and it is supposed to sit there loose. A bond breaker between the brick and that ledge lets the two move at their own pace. Leave it out and mortar glues the first course of brick straight to the grade beam. Now every time the brick swells in the heat and shrinks in the cool it drags the corner of the concrete along with it. Concrete takes compression well and tension badly, and the corner is the least confined piece of the beam, so the corner is what breaks. The Foundation Performance Association, an engineering group that publishes committee papers on how slabs behave on expansive soil, puts spalled concrete at the corner of a foundation carrying a brick wall on its list of problems that get blamed on foundation movement by mistake, and names the missing bond breaker as the reason. So yes, corner pop is normal. On brick homes here it is one of the more common cosmetic defects we see, and we find it on houses whose floors measure flat.

Why it shows up on the sunny sides of the house first

Temperature is the engine, so the walls that take the most sun move the most. South and west elevations in Central Texas run hot from spring through October, and the brick on them swells further and cools further than the brick on a shaded wall. That is why a house often has one popped corner on the west side and three quiet corners everywhere else, and why the same corner can look worse in September than it did in March. The timing is also why corner pop gets misread. Late summer is when the clay is at its driest and doors start to stick, so the harmless corner and the real symptoms arrive in the same week and get blamed on each other. What the brick does to the concrete has nothing to do with how our soil moves.

When corner pop is telling you something real

A popped corner on its own is a patch job. A popped corner with company is a measurement job, and the tell is direction. Corner pop breaks outward through the face of the concrete and stops there. Movement runs down into the beam, and it never shows up alone. The crack carries on from the corner into the grade beam and widens as it goes down. Stair-step cracking in the brick above it opens along the mortar joints. One face of the crack sits proud of the other, so a fingernail catches on the offset. Doors near that corner start rubbing, or a slope shows up in the floor inside. Any one of those changes the answer, and the corner earns an elevation survey instead of a bag of patch. The American Society of Civil Engineers draws the same line, that measured movement is what separates cosmetic damage from structural damage. A chip of concrete carries none. For the whole triage, sorting cosmetic cracks from structural ones works through it pattern by pattern, and signs that actually indicate movement lists what does count.

How corner pop gets repaired

Chip the loose material away with a cold chisel until you reach sound concrete, brush the dust off, rinse it and let it dry. Coat the break with a concrete bonding agent, then rebuild the corner profile with non-shrink grout or a polymer-modified repair mortar, in layers if the chip was deep. Keep the patch damp or covered for a day so it cures slowly, then paint if the rest of the slab edge is painted. While you are down there, aim the sprinkler heads away from the slab edge and keep the soil graded so water leaves. That is the whole repair. It needs no permit and no engineer. A handy owner can do it in an afternoon and a mason can do it faster. Piers stabilize a house that has lost elevation. They do nothing at all for a corner that broke because the brick was stuck to it.

What corner pop repair costs

Corner pop is the cheapest thing on any foundation worry list. It is a bag of patch material and an afternoon if you do it yourself, or a short visit if you hire it out, and it stays masonry priced either way. Set that next to real foundation work. The pier prices we publish on the Texas cost page run about $600 to $1,000 per pier installed, and a genuinely settled corner of four to six piers lands around $2,500 to $6,000. Those numbers belong to a measured elevation loss. They do not belong to a broken corner. If a contractor walks your perimeter, points at a spalled corner and writes a pier proposal on the strength of it, stop the conversation and get a second opinion. Insurance rarely helps either. Cosmetic spalling reads as wear, and policies pay for sudden events, so the cases that do get covered are the ones laid out in foundation insurance coverage in Texas. A popped corner belongs on the same list as everything else in what gets blamed on foundations.

What we check before we call a corner pop cosmetic

We do not call a corner cosmetic from the driveway. The inspection starts with elevations taken across the whole floor, because that reading is the only thing that separates a corner that moved from a corner that broke. Then we look up at the brick courses and the door and window openings on that wall. Then we look into the break itself. If the concrete spalled because water reached the reinforcing steel and rusted it, the steel swells as it corrodes and pushes the cover off from the inside, and that corner needs the steel cleaned and protected rather than a skim of patch over a live problem. That is the one case where the answer changes, and the same Foundation Performance Association paper covers it too. Last we walk the drainage and the grade around that corner, because a slab edge that stays wet keeps losing material no matter how well the patch went on. Motmot is ICC-certified and inspector-led, and we work alongside independent Texas licensed engineers when a reading calls for one. No repair needed is where about a third of our inspections land, and a popped corner is a common way to arrive there. Before you assume either answer, check whether the doors on that wall still latch and whether the brick courses above the corner still run straight.