Reading your foundation: 7 signs worth a walk-through

Foundations rarely fail overnight. They settle, shift, and crack in slow motion — usually over years. Most homeowners catch the signs months or even years before the problem becomes structural, but only if they know what to look for. This is a 30-minute walk-through you can do yourself, today, with no tools.

If you spot any of the seven signs below, it doesn't mean your foundation is failing. It means it's worth a closer look — sometimes from a contractor, sometimes from a structural engineer, sometimes both. The goal here is awareness, not alarm.

1. Door drag.

Doors that won't latch, swing open or closed on their own, or scrape the floor at the bottom are the most common early signal. Wood doors swell and contract with humidity, so a single sticky door in winter isn't necessarily structural. But two or three doors going off at the same time, especially in different rooms, often means the building has shifted.

2. Hairline cracks at door + window corners.

Cracks radiating diagonally from the corners of door frames or windows are a classic sign of differential settlement. Tiny vertical cracks are usually drywall stress; diagonal cracks mean the framing around the opening is being twisted by the structure underneath.

3. Cracks at exterior corners or stair-step cracks in masonry.

Step-shaped cracks following the mortar lines on a brick or block exterior are a structural cue. Vertical cracks at the corners of a stucco exterior — particularly ones that get wider near the top or bottom — also warrant attention. Hairline cracks in plain stucco are common from thermal expansion; widening cracks are not.

4. Floors that slope or feel "off."

Walk barefoot through every room. Drop a marble at one end of the room and watch what it does. A floor that's noticeably out of level — particularly one that's gotten worse over the years — is a signal worth investigating. Some 70+ year-old homes have always been a half-inch out and remain stable; the question is whether the slope is changing.

5. Gaps between baseboards and floors, or moldings and walls.

Gaps where the baseboard pulls away from the floor, or the crown molding pulls away from the ceiling, indicate the framing has moved. Gaps that grow over months are more concerning than long-standing gaps that haven't changed.

6. Water in the crawlspace or basement.

If you have access to a crawlspace, take a flashlight and look at the perimeter foundation walls. Mineral staining (white efflorescence), wet wood, or pooling water means moisture is moving through or around your foundation — and over time, that's a primary driver of foundation deterioration. Drainage problems are often easier to fix than foundation problems, but they need addressing either way.

7. Chimney leaning, separating, or pulling away from the house.

Brick chimneys are a separate seismic concern but they also signal foundation movement. A chimney that's separated from the exterior wall, or noticeably leans away from plumb, suggests the foundation under the chimney has settled differentially from the foundation under the house. This is particularly common in older Bay Area homes built before modern code.

What to do next

If you've spotted one or two cues that haven't changed in years, you're probably looking at long-term character — not active failure. If you've spotted three or more, or if any of them have visibly worsened in the past year, it's worth getting a contractor to walk the property and a structural engineer to weigh in if needed.