Do cracks always mean my slab needs repair?

No. Many cracks in a house are cosmetic — drywall shrinkage, thermal movement, settling of finishes, or an old crack reopening because the patch was the weakest point. What makes a crack worth investigating is its location and pattern, whether it corresponds to other observations elsewhere in the house, and above all whether it is changing. A photograph cannot establish any of that. An evaluation with elevation readings can.

What should I document first?

Where each observation is, what it looks like, and the date. Photograph cracks twice — one wide shot showing the location on the wall and one close shot with a tape or coin for scale. Mark the end of a crack lightly in pencil and date the mark, then re-photograph in four to six weeks. Note which doors bind and on which edge. That dated record is more useful to an evaluator than any single close-up.

Are sticking doors a slab problem?

They can be, and they are a useful early indicator because door frames respond to small changes in geometry. They also respond to humidity — timber swells in damp weather and shrinks in dry. A door that binds in August and clears in November is probably telling you about the season. Several doors on the same side of the house binding on the same edge, persisting across seasons, is a different signal.

Is there a crack width that means it is structural?

No, and any single number presented as a threshold is an oversimplification. Width is one attribute and not the most informative one. A narrow crack that is lengthening steadily matters more than a wider one that has not moved in years. Direction, pattern, relationship to openings, and change over time all carry more information than the measurement across the gap.

When should I actually call someone?

When something is changing, when more than one observation lines up in the same part of the house, when a door or window has stopped functioning, when you see separation between the house and a porch or addition, or when you are buying or selling and need the question answered with documentation. Static, minor, isolated cosmetic cracking unchanged for years is a monitoring situation.

Signs Your Slab Foundation Needs Repair

The observations that make slab foundation repair worth investigating, and the ones that do not.

Start with the principle

An observation is not a diagnosis.

What you can see — a crack, a gap, a door that catches — is a fact. What it means is a conclusion that requires measurement and context. Everything below is a list of observations worth taking seriously, and none of them establishes on its own that your slab needs repair.

That distinction matters commercially. A pier count produced from a look at a crack is a commercial estimate, not an assessment, and it is usually generous in the estimator’s favor.

The observations that matter on a slab home

Cracks in interior walls

Diagonal cracks running from the upper corners of door and window openings are the pattern worth noting, because openings concentrate stress. Cracks at the junction of wall and ceiling, and cracks that reopen in the same place after being patched, are also informative — a reopened patch tells you something moved after the patch went in.

Hairline cracking scattered through a house with no pattern is usually finishes behaving normally.

Exterior masonry

Stair-step cracking following the mortar joints in brick veneer, typically radiating from a window or door opening or appearing near a corner. Worth photographing and worth watching.

Also worth noting: whether the crack is wider at the top or the bottom, and whether anything inside the house lines up with it.

Separations

Gaps opening between baseboard or trim and the wall. Gaps where a porch, step, or addition meets the main structure. Separation between brick veneer and a window frame.

These matter because they indicate two parts of a structure moving relative to each other, which is more specific information than a crack in a single surface.

Visible gap between a baseboard and the floor along a wall in a carpeted room

Doors and windows

Doors that bind, latches that no longer line up, windows that have become hard to operate. Walk the house and operate every door rather than relying on the one you noticed.

The pattern across the house is what carries information. One sticky door in a hallway is probably just a door.

Floors

A room that feels like it falls toward one side. Tile cracked in a line rather than in one spot. A hardwood floor that has developed a noticeable slope near one wall.

Some slope exists in nearly every house including new construction. Magnitude, distribution, and change are the questions.

Outside at ground level

Soil pulled back from the slab edge in a dry spell. Water pooling against the foundation after rain. A downspout discharging right at the wall. A large tree very close to the perimeter, or one that has recently been removed.

Exterior gap where a concrete porch slab has separated from the brick wall of a home

What appearance alone cannot establish

The question	Why a photo cannot answer it
How much has the slab moved?	Requires relative elevation readings across the house
Which direction — settlement or heave?	Requires the elevation pattern, not the crack
Is it still moving?	Requires two dated observations, not one
What caused it?	Requires drainage, plumbing, tree, and construction context
How many supports would it need?	Requires the survey and the load path

Anyone answering those from an image is guessing.

What to do before calling anyone

Document it. Dated photographs, wide and close, with scale. Pencil marks at crack ends with the date beside them. A note of which doors are affected.

Check the cheap causes. Downspout discharging at the foundation? Irrigation zone soaking one corner? Gutter blocked? Grade falling toward the house? Some of these you can fix in an afternoon, and one of them may be the entire explanation.

Wait and re-photograph. Four to six weeks later. Change is the single most useful piece of evidence there is, and it costs nothing to collect.

When to get it measured

If observations are changing, if several line up on one side of the house, if something has stopped working, or if you need documentation for a sale — that is when a foundation evaluation earns its cost, because the elevation survey turns observations into evidence.

If the evidence supports work, slab foundation repair explains what that involves, and what to expect during a slab foundation repair project walks through the sequence on site. If it does not, a good evaluation says so and you keep the report either way.