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Homeowner guide

Common Foundation Warning Signs in San Antonio Homes

The observations that prompt San Antonio homeowners to ask about their foundation, and how to tell a symptom from a diagnosis.

5 min read
Homeowner examining an exterior wall crack on a San Antonio brick home in daylight

What Homeowners Actually Notice First

Nobody notices a foundation. What people notice is a door that has started catching on the jamb, a crack running up from a window corner, or the odd sensation of a floor that is not quite flat under bare feet.

Those observations are worth taking seriously and they are also worth putting in proportion. Most of them, individually, are ambiguous. The purpose of this guide is to describe the four things San Antonio homeowners most often report, explain what each one can indicate, and be clear about where the line sits between noticing something and knowing what it means.

Close-up of a sticking interior door with a gap at the top jamb

The four observations below account for the large majority of calls we take. If one of them brought you here, the honest first thing to say is that the answer to “is this serious” comes from measurement, not from a photograph, and a foundation evaluation is where that measurement happens.

The Four Common Observations

Cracks in exterior brick and mortar

Usually diagonal, following the mortar joints in a stair-step pattern, and most often starting at the corner of a window or door opening. Masonry cracks through the joints because mortar is weaker than brick, so this pattern appears whenever a brick wall is stressed for any reason.

That reason can be foundation movement. It can also be thermal expansion in a wall without adequate expansion joints, deflection in a lintel over an opening, or an original construction detail. Width, displacement, and whether the crack is changing carry far more information than the pattern. There is more detail in our guide on whether brick and mortar cracks are a foundation problem.

Cracks inside, usually above openings

Interior cracking typically appears above door and window frames, at wall-to-ceiling junctions, and at corners. Fine hairline cracking along drywall tape joints is extremely common and often seasonal, as materials expand and contract with humidity. Cracks that are wider, that run diagonally from a corner, or that reopen after being patched are a different observation.

Doors and windows that stick

Timber swells in humid weather and shrinks in dry weather, so a degree of seasonal sticking is normal in San Antonio and reverses as conditions change. What is worth attention is sticking that has worsened steadily over years regardless of season, or that appears alongside cracking in the same part of the house.

Uneven or sloping floors

Often noticed by accident: a dropped marble that rolls, furniture that rocks, a rug that never sits flat. Almost every house has some deflection, and the relevant questions are how much, where the low point is, and whether it is changing. Those are measurement questions.

What Is Also Worth Documenting

  • Gaps opening between baseboards and the floor, or between trim and the wall.
  • Separation where brick meets a window or door frame.
  • Doors that no longer sit square in their frames.
  • Gaps at the junction between an original structure and a later addition.
  • Cracks that reappear in the same place after being repaired.

Why Appearance Alone Cannot Establish Movement

This is the central point of the guide and it is worth stating plainly.

A photograph of a crack tells you the crack exists. It does not tell you whether the crack formed five years ago and has been stable ever since, whether it is widening now, whether the floor behind it has dropped, or what caused it. Two visually identical cracks can sit above a perfectly flat floor and a floor with significant differential settlement respectively.

What resolves the question is an elevation survey: relative floor height measured across the whole plan and plotted, so the shape of the floor becomes visible. That profile shows whether a corner has dropped, whether a perimeter has lifted, or whether the centre has risen. Each of those points to something different, and only one of them is ordinary settlement.

What we will not do

We will not tell you your foundation needs repair based on a photograph, and we would be cautious about anyone who does. The observation is yours to make. The measurement is ours.

What to Document Before Anyone Visits

Doing this before an evaluation makes the visit considerably more useful, and it costs nothing.

  1. Photograph every visible crack with a ruler or coin held flat against the surface, and note the date.
  2. Mark the ends of each crack with a light pencil line and date the mark.
  3. Note which doors and windows stick, and at which point they catch.
  4. Note where floors feel uneven, room by room.
  5. Write down roughly when you first noticed each thing, and whether it has changed since.
  6. Gather any paperwork from previous foundation work, including proposals, engineering letters, and warranties.

If you can repeat the photographs after a wet season and again after a dry one, the comparison between them is more informative than any single image.

When to Request an Evaluation

Request one when a crack has visibly widened, when displacement has appeared so one side sits proud of the other, when the same crack keeps reopening after repair, when door operation has worsened progressively rather than seasonally, or when several of these observations are appearing together in the same part of the house.

It is also reasonable to request one simply to establish a baseline, particularly before buying or selling. A measured profile you can compare against in three years is worth having even when the current answer is that nothing needs doing.

If what you are seeing is stable and isolated, documenting it through a season is often the better use of your time, and we will tell you that rather than booking a visit you do not need.

Quick answers

Questions About This Topic

Do all foundation cracks mean I need repair?

No. Many cracks are cosmetic, seasonal, or the result of ordinary curing and thermal movement. What distinguishes a crack that matters is whether it is changing, whether it shows displacement, and what the floor elevation profile behind it looks like. An evaluation measures those things; appearance alone does not establish them.

What should I photograph before an evaluation?

Photograph every visible crack with something of known size held flat against the surface for scale, such as a ruler or a coin. Include the wider context as well as the close-up so the location is clear. Also photograph sticking doors at the point they catch, and any gaps at trim or baseboards. Write the date on each image.

How fast should I act on foundation signs?

It depends on the sign. A crack that has been the same width for three years is not urgent. A crack that has visibly widened over a few months, a door that has progressively worsened, or a floor that has become noticeably uneven warrants a prompt evaluation. Sudden change is the signal worth acting on, not the presence of a crack itself.

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