If you live in Mobile or Baldwin County and you own your home long enough, you will eventually find a crack in a wall, ceiling, or above a doorway. The question is whether it’s cosmetic settling that anyone can patch with $8 of spackle, or the first visible sign of expansive-clay soil movement that’s going to cost you $15,000+ if you let it run for five years.
We do free foundation inspections across the Mobile metro every week, and we see the same five crack patterns over and over. Here’s how to read each one yourself before deciding whether to call us.
1. Hairline horizontal crack above a doorway or window
This is the most common and least concerning pattern in Mobile homes. A thin (under 1/16 inch) horizontal crack just above a door or window header is usually drywall stress from normal humidity-cycling — drywall expands when summer humidity hits and contracts when winter pulls it back. Over a few years of cycles, you get hairline cracks at the weakest joints, which are the corners of openings.
What it means: Almost always cosmetic. Patch with caulk (not spackle — spackle is brittle and re-cracks; flexible caulk handles future movement).
When to actually worry: If the same crack widens to 1/8 inch+, or if it grows season-over-season, or if you start seeing the same pattern on multiple openings across the house, that’s no longer drywall stress — that’s structural movement and time to get an inspection.
2. Diagonal crack running from a corner of a door or window
This is where things get interesting. A diagonal crack that starts at the corner of a door or window frame and runs upward at a 30–60 degree angle is the classic signature of foundation settlement — one part of the foundation is dropping relative to the rest, and the structure above is shearing along its weakest plane.
What it means in Mobile: Usually one side of your foundation is sitting on soil that’s lost moisture (and shrunk), while the other side is on stable ground. Common after a long dry summer, especially if there’s a large tree nearby pulling water from the soil under the foundation.
What to do: This is worth a free inspection. We measure floor levels with a precision laser across the entire house — if there’s more than 1 inch of differential across 20 feet of floor, you have an actual structural problem developing. If it’s less than that, monitor for 6 months before doing anything beyond cosmetic patching.
Cost range if it IS structural: $3,000–$8,000 for targeted polyurethane foam injection if caught early. $15,000–$50,000 if you wait until it’s lifting hardwood and jamming every door.
3. Stair-step crack in brick or block exterior
Stair-step cracks following the mortar joints of brick veneer or block walls — that distinct zigzag pattern — are the most reliable visual indicator of foundation movement in Gulf Coast homes. The brick is essentially riding on top of the foundation, so when the foundation moves, the brick cracks along the mortar (which is weaker than the brick itself) in that telltale stair pattern.
What it means: Foundation is actively settling or heaving in that section. Heaving is more common in Mobile than pure settlement because our expansive clay swells dramatically when it gets wet — and Mobile gets very, very wet.
What to do: Don’t ignore this one. Stair-step cracks in brick almost always indicate active movement that will continue. Get a free inspection within 30 days. Repair is usually $5,000–$15,000 if you catch it before the cracks widen past 1/2 inch.
4. Floor that’s noticeably sloped or “bouncy”
Walk barefoot through every room of your house carrying a marble. If the marble rolls consistently in one direction in a room, the floor in that room is sloped. If you can feel the floor flex when you walk on certain spots (“bouncy” feel), the subfloor structure is failing — usually because of crawl space moisture, joist rot, or pier settlement.
What it means in Mobile: Crawl space humidity, undersized supports, or rotted floor framing from chronic moisture. Sometimes it’s the foundation itself; sometimes it’s just the crawl. Hard to tell without inspection.
What to do: Free crawl space inspection. Headlamp + flashlight check of every pier, joist, and beam. We can tell within 30 minutes whether you’re looking at a $1,500 sistering job or a $20,000 crawl + foundation combination repair.
5. Doors that won’t latch or windows that stick
When doors that used to close fine start needing a shove, or windows you used to open easily are suddenly stuck, the door or window frame is no longer square — which means the wall above it has racked. Wall racking comes from foundation movement.
What it means: Foundation has shifted enough that the frames in the walls above it are no longer plumb. Often this is the first thing homeowners notice — before they spot any cracks.
What to do: Check multiple doors and windows. If only one is acting up, it’s usually just normal seasonal swelling — wait it out. If three or more doors/windows across different rooms are sticking simultaneously, that’s structural and worth a free inspection.
When to actually call
Mobile sits on some of the most expansive clay soil in the continental US. National statistics: 1 in 4 American homes experiences some level of foundation distress over its lifetime. In Gulf Coast clay zones, that number climbs to 4 in 10. The single best decision you can make as a Mobile-area homeowner is to get a baseline inspection before you ever have a problem — so when you do start seeing cracks, you have a comparison point to know whether they’re new or old.
We do these free, with thermal imaging, soil-moisture mapping, and a written report. No high-pressure sales pitch — about 60% of our inspections result in “you’re fine, monitor and check back in 2 years.” We make money on the 40% who actually need work, not by manufacturing problems for the rest.
If you’ve noticed any of these five patterns and want to know what you’re actually dealing with, call us at (251) 555-0200. Mobile-area crew on-site within 48 hours, free written estimate same day in most cases, no obligation.