Foundation cracks: when to call a structural engineer

Which foundation cracks are cosmetic and which ones need an engineer? Warning signs, what an independent foundation evaluation covers and why it helps before you hire a repair contractor.

Almost every house has cracks. Concrete shrinks as it cures, and houses move a little with the seasons. Most cracks are cosmetic. Some point to settlement, soil movement or water pressure that will keep getting worse. A foundation evaluation by a structural engineer tells you which case you are in before you spend money on repairs.

Cracks that are usually cosmetic

thin, vertical or slightly diagonal hairline cracks in a poured concrete wall or slab;
cracks that have not changed in width for a long time;
small cracks in drywall corners after the first years of a new house.

Keep an eye on them: mark the ends with a pencil and the date, and take photos.

Signs that call for an engineer

horizontal cracks in a basement wall, or a wall that bows or leans inward;
stair-step cracks in block or brick;
cracks that are wide, that keep growing, or where one side has shifted relative to the other;
sloping floors, doors and windows that stick, gaps between walls and ceiling;
cracks together with water coming in, or after a flood, a drought or nearby excavation.

Why an independent engineer first

Foundation repair companies often offer a free inspection, but they are paid to sell the repair. A structural engineer is paid for the evaluation only. Their report gives you:

the likely cause (soil settlement, expansive clay, poor drainage, hydrostatic pressure, overloading);
whether the condition is structural and how urgent it is;
a repair scope (for example piers, wall anchors or braces, drainage improvements, or simply monitoring);
a neutral basis to compare repair bids, and a sealed letter you can show buyers, lenders or your insurer.

Some repairs need a permit and an engineer's design. After the work, many homeowners ask the engineer to come back and confirm that it was done as specified: this letter is valuable when you sell.

Before the visit

Gather photos, dates and any earlier reports or repair warranties.
Note when you first saw each crack and whether it changed.
Make the basement, crawl space and exterior walls accessible.

Describe the cracks in the form: licensed structural engineers near you get back to you with a quote for a foundation evaluation.