The signs, and what else could cause them
The right column matters as much as the left. Use it to rule things out before you worry, and use it to give a contractor useful information.
| What you notice | What it can point to | It could be something else |
|---|---|---|
| Doors or windows that stick or won’t latch | Frame racking because a wall or corner has shifted | Seasonal humidity swelling wood; a house that has settled slightly and stopped; paint buildup; loose hinges |
| Floors that slope, bounce or feel soft over a crawl space | Sagging joists or girders, a settled pier, damaged framing | Old, undersized framing that was never level; subfloor damage; a moisture problem rotting the wood |
| Cracks in a slab | Differential settlement or heave | Normal shrinkage as concrete cured; cracks at control joints; long-stable hairline cracks |
| Stair-step cracks in brick or block | Movement in the wall or footing below | Old mortar failing; water behind the wall; settling that ended decades ago |
| Hairline drywall cracks, especially at corners and door tops | Early movement, if growing | Seasonal drying, normal settling, nail pops, poor tape work |
| Gaps between walls and ceiling or trim | Movement in framing or foundation | Wood shrinking and swelling with humidity |
| Chimney, porch or steps pulling away | Differential settlement at an attached structure | Footings that were never tied in; erosion; drainage |
| Bowing or leaning foundation or masonry wall | Lateral soil pressure | Water against the wall; poor backfill; a retaining wall that is separate from the house |
| Standing water or soft ground at the wall | Poor drainage, which can lead to movement | Gutter overflow, a leaking hose bib, a regrading issue |
| Musty smell or visible mold under the house | Moisture, which can damage framing over time | A plumbing leak, a vented crawl space in a humid season, a dryer vent discharging underneath |
How to tell if it is moving
A one-time look can’t separate an old crack from a new one. A few simple habits help.
- Mark the ends of a crack with a pencil and write the date. Check again in a month or two.
- Measure the width with a crack gauge or a card with lines on it, and write it down.
- Check doors across seasons. A door that sticks only in humid weather is a moisture problem, not a foundation one.
- Use a level or a marble on a floor you suspect. Look at where it slopes, not only how much.
- Look in the crawl space if you can do so safely: sagging joists, gaps at piers, damp or dark wood, and daylight where there shouldn’t be any.
Photos with dates are useful to bring to an inspection.
Call to schedule an inspection
Why Charlotte houses show these signs
Several things in Mecklenburg County can produce them. The county’s soil survey maps soils from low to very high for shrink-swell, and neighbouring lots can sit on different ones. The NC Geological Survey lists cracked walls, uneven floors and foundation cracks among the results of shrink-swell movement. Mecklenburg County has also been through drought, with the whole county in extreme drought this spring. And many houses here are not new: the median home in the county was built in 1997, and 25% of homes date from before 1980.
Humidity matters too. NOAA’s normals put Charlotte’s July mean dew point at 67.7 degrees F dew point. Wet air under a vented crawl space can damage wood, which shows up as soft or sloping floors long before a foundation fails.
That is a list of possible causes, not a finding about your house. The Charlotte soil guide explains how to look up your parcel’s soil.
What usually is not the foundation
Many calls turn out to be something simpler. These are common in Charlotte houses:
- Sticking doors in summer. Wood absorbs moisture when the air is humid. If the door eases in winter and nothing else has changed, it is probably a humidity issue.
- Hairline drywall cracks. Joints in drywall crack as a house dries out and moves a little through the seasons.
- Small slab cracks that never change. Concrete shrinks as it cures, and many cracks appear in the first years and stop.
- Bounce in a floor above a wide span. Sometimes the framing was always springy. Compare with how it felt when you bought the house.
- Musty smells. These point to moisture, not structure, unless the wood is soft.
Ruling these out is part of an inspection. A contractor who tells you nothing needs doing has given you useful information.
Call to schedule an inspection
What an inspector looks at
When someone visits, expect them to check how level the floors are, measure crack widths, look at the crawl space or slab edge, check piers, joists and girders for sag or rot, and look at gutters, grading and downspouts. They should explain the cause they suspect and what would confirm it. NC home inspector standards require inspectors to enter a crawl space unless access is blocked, and to probe structural components where deterioration is suspected, which is the same kind of look a foundation contractor takes.
When to ask for an inspection
Ask sooner rather than later if you see any of these:
- A crack that has widened or lengthened since you marked it.
- A floor that now slopes or bounces where it did not before.
- Several signs appearing together, such as sticking doors, new cracks and a gap at the ceiling.
- Water pooling near a wall, or damp, dark wood under the house.
- A pending sale. North Carolina’s seller disclosure form asks about foundation problems, and a buyer’s home inspector may flag them.
An inspection also gives you a baseline, even if the answer is that nothing needs doing. Read what to expect on the foundation inspection page, and if cracks are your main concern see foundation crack repair.
Call to schedule an inspection
Before you sign
If an inspection leads to a repair proposal:
- Ask what was found, where, and how it connects to the signs you noticed.
- Ask what else could explain them, and why that was ruled out.
- Be wary of a low price followed by alarming, expensive findings.
- Get at least three written estimates where you can.
- Get the scope, cost and completion date in a written contract.
See the repair cost guide for how to read a quote.
Charlotte Foundation Guys runs this site and the phone line. Work is done by independent local contractors, and pricing and availability are set by the contractor serving your area.
Want a contractor to look at it? Call to schedule an inspection.