What a Self-Check Can and Cannot Tell You
A self-check can tell you:
- Where cracks, gaps, and slopes are, and how big they are today
- Whether they grow or spread between checks
- Whether water is reaching the foundation
It cannot tell you:
- What is causing the movement, or whether it has stopped
- What is happening inside walls, under a slab, or at the footings
- Whether the structure is still adequate, or which repair it needs
Even a standard home inspection stops short of those judgments: the ASHI Standards of Practice call it not technically exhaustive and do not require the inspector to judge the adequacy of structural systems. If you would rather hand the job over, see what a professional foundation inspection covers.
What You Need for a DIY Foundation Inspection
- Flashlight: a bright LED light, plus a headlamp for a crawlspace
- Level or marble: a 4-foot level gives a number; a marble shows only direction
- Tape measure: a 25-foot tape and a ruler marked in 1/16 inch
- Crack gauge or coin: a plastic crack width card, or pennies as a rough stand-in
- Phone camera: photograph each finding with the tape in the frame
- Notebook: for your log, plus a pencil for marking crack ends
A string line, a line level, and a screwdriver help too. Repeat the walk-through each spring and fall, and if you can, walk the outside once during heavy rain to see where the water goes.
Exterior Walk-Around Checklist
Start outside, since the earliest signs of foundation problems often appear where water meets the perimeter.
Grading and drainage
- Soil should fall away from the house. The International Residential Code sets a minimum of 6 inches of fall within the first 10 feet. Test it by running a leveled string from the wall to a stake 10 feet out and measuring the drop.
- Patios and walks within 10 feet should slope away at 2 percent or more, about 1/4 inch per foot.
- The code also requires at least 4 inches of foundation wall above the soil where there is brick veneer, and 6 inches elsewhere. Mulch piled higher keeps the wall damp.
- Downspouts should release water at least 4 to 6 feet from the foundation.
- Look for puddles along the wall, and for soil shrinking away from it, a common sign of drying clay.
If water collects against the house, the fixes for water around the foundation usually cost far less than foundation repair.
Visible cracks and their direction
- Record each crack’s direction: vertical, diagonal, horizontal, or stair-step through mortar joints.
- Check whether one side sits higher or further out than the other. Offset matters more than width.
- Note whether it is wider at the top or the bottom. The taper shows which part of the wall is moving.
Brick, siding, windows, and doors
- Stair-step cracks in brick, or brick pulling away from window frames, door frames, or the trim under the eaves
- Siding buckled or opened at the corners, and torn caulk or uneven gaps around windows and doors
Chimney lean
- Sight the chimney against a house corner from across the yard. A lean, or a gap at the wall that widens toward the top, often means its footing is settling.
Interior Living Spaces Checklist
Inside, you are looking for the frame distorting as the foundation below it moves.
Doors and windows
- Open and close every door. Note any that stick, rub, fail to latch, or swing on their own.
- The gap between door and frame should be even across the top. A wedge-shaped gap means the frame has racked.
- Work each window. New sticking matters more than old, since humidity alone makes some bind in summer.
Drywall and trim
- Diagonal cracks running from the corners of doors and windows, the classic sign of differential settlement
- Cracks where walls meet the ceiling, and nail pops lined up along one wall
- Baseboards lifting off the floor, crown molding opening at corners, and tile cracking in a line across the floor
Not every crack is structural. Tape seams crack as framing lumber dries in a new house, and ceiling gaps that open each winter and close each summer are usually truss uplift in the roof.
Floor slope
- Set a marble in the middle of each room and see where it rolls. That shows direction only.
- For a number, lay a 4-foot level on the floor, raise the low end until the bubble centers, and measure the gap beneath it. Take readings in several directions.
Many engineers treat about 1 inch of slope over 20 feet as worth investigating and more than 1 inch over 10 feet as a reason to call someone. Under a 4-foot level, those equal gaps of roughly 3/16 inch and just over 3/8 inch. The guide to uneven floors explains what causes each pattern.
Basement Checklist
- Vertical cracks: Hairline vertical cracks in poured concrete are usually shrinkage. Note the width and any seepage.
- Horizontal cracks: Often near mid-height, these usually mean soil pressure is pushing the wall inward. Call a professional at any width.
- Stair-step cracks: In block walls they follow the mortar joints and point to settlement or soil pressure.
- Bowing: Stretch a string along the wall, held off each end by equal blocks, and measure from string to wall every few feet. A smaller gap mid-wall means an inward bow, and a level held upright shows whether the top has tipped in. See bowing basement walls for how the amount of bow changes the repair.
- Water staining: Tide lines, rust marks, peeling paint, or damp strips where floor meets wall
- Efflorescence: White, chalky deposits left as water passes through concrete. Mist it with water: efflorescence dissolves and mold does not. It signals moisture, not structural damage.
- Damp smell: A lingering musty odor means moisture, even where no water shows.
- Posts and beams: Steel posts should stand plumb, with no sag in the beam between them.
Crawlspace Checklist
Safety first. The ASHI standard does not require a professional inspector to enter a crawlspace with less than 24 inches of vertical clearance or a hatch smaller than 16 by 24 inches. If yours is tighter, flooded, or shows animals or loose wiring, inspect from the hatch with a flashlight and phone camera. Otherwise wear gloves and a mask, and tell someone before you go in.
- Standing water: Pools, saturated soil, or water lines on piers. The wet crawl space guide covers the sources and how to dry it out.
- Moisture: Condensation on ducts, fallen insulation, and a torn or missing vapor barrier
- Piers: Each should be plumb, uncracked, and in full contact with the beam. Look for leaning or sunken piers, crushed or rotted shims, and gaps under the beam.
- Joists and beams: Look for sagging, cracks, and joists notched for pipes. Press a screwdriver into the wood; if the tip sinks in easily, it is likely rotting.
- Mold and pests: Fuzzy or dark growth on the framing, and termite mud tubes running up piers or walls
Garage and Slab Checklist
- Garage floor cracks: Most garage slabs crack, and many are poured separately from the house. Worry about cracks where one edge sits higher than the other.
- Door line: A slab that has dropped at the entrance, or a closed door that leaves a gap wider at one end
- Wall joints: Separation between the slab and the foundation wall, or where the garage meets the house
- Slab edges: Small triangular breaks at slab corners, called corner pops, are usually cosmetic. Long cracks through the slab edge are not.
- Leak signs: Warm spots on the floor, the sound of running water with every tap off, or a jump in the water bill. A leak under a slab can wash out or swell the soil beneath it.
How to Measure and Record a Crack
One reading tells you little. Consistent records let you compare like with like next season.
- Mark both ends with a short pencil line across the crack and date each mark.
- Pick two or three points, including the widest, and label them A, B, and C.
- Measure each point with a crack width card. Without one, use pennies: each is about 1/16 inch thick, so if a stack of four slides in, the crack is roughly 1/4 inch.
- Measure the length, and note the direction and any offset.
- Photograph the whole crack from a spot you can find again, then each point up close with the tape against the wall.
- Note the weather, since cracks in clay soil often open in dry months and close in wet ones.
Keep one log for the whole walk-through, one line per finding with the date, location, measurement, and photo number, so each check lines up against the last. For long-term tracking, tell-tale gauges, and telling seasonal movement from real growth, follow the foundation crack monitoring guide.
What Your Findings Likely Mean
Use this table as a quick foundation assessment checklist. It is triage, not a diagnosis.
| What you found | Likely meaning | Urgency |
|---|---|---|
| Hairline vertical crack, no offset | Concrete shrinkage | Low: recheck twice a year |
| Crack 1/16 to 1/4 inch, no offset | Settlement, possibly still active | Moderate: measure monthly for three months |
| Crack over 1/4 inch, or sides offset | Significant or ongoing movement | High: book a professional |
| Horizontal crack in a basement wall | Soil pressure pushing the wall in | High at any width |
| Basement wall bowing or leaning | Wall yielding to soil pressure | High; urgent past 2 inches |
| Stair-step cracks in brick or block | Settlement or soil pressure | Moderate to high, by width and offset |
| Floor slope over 1 inch in 10 feet | Settlement or failing supports | High: book a professional |
| Efflorescence or water stains only | Water moving through the walls | Low to moderate: fix drainage |
| Standing water in a crawlspace | Drainage failure under the house | Moderate to high: fix drainage, check wood |
| Rotted joists, or piers not touching beams | Decay or pier settlement | High: book a professional |
| Chimney pulling away from the wall | Chimney footing settling | High: book a professional |
| Soil sloping toward the house | Water soaking the soil at the footing | Fix now, often as a DIY job |
Diagonal drywall cracks or a sticking door on their own usually call for measuring and rechecking, not a repair. When several findings cluster on one side of the house, treat the group as one level more urgent than any single item.
Why Your Soil Type Matters
Expansive clay swells when wet and shrinks when dry, so houses on it move with the seasons and after droughts. Loose fill and organic soils compress under load, and sandy soils wash out where water concentrates. The same crack means more on some soils than others.
You can look up your soil for free in the USDA Web Soil Survey. Enter your address, draw a box around your lot as the area of interest, and open the soil map to see which soil units lie under the house. In the Soil Data Explorer tab, the Building Site Development ratings for Dwellings With Basements and Dwellings Without Basements show whether the soil is not limited, somewhat limited, or very limited for homes, and linear extensibility shows shrink-swell potential. The maps describe typical conditions across an area rather than the exact soil under your footings, so treat the result as background.
When a Finding Means Calling a Professional
Knowing how to inspect a foundation yourself does not mean handling every finding yourself. Book a professional if you find any of these:
- A crack wider than 1/4 inch, or any crack with one side offset
- Any horizontal crack in a basement or block wall
- A basement wall that bows or leans inward
- A crack that grows more than about 1/16 inch in three months, or keeps lengthening
- Floor slope over 1 inch in 10 feet, or slope that is new
- Cracks, sticking doors, and sloping floors together in one part of the house
- Rotted framing, leaning piers, or beams no longer resting on their piers
- A chimney pulling away from the wall
- Sudden changes after a flood, a long drought, or excavation next door
Bring your log and photos. Dated measurements show a trend that a single visit cannot.
A foundation contractor can give a practical repair scope, often free, but also sells the repair. A licensed structural engineer charges a fee and gives an independent diagnosis. The foundation inspection guide compares these options, what each costs, and what a good report should contain.