How to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for CracksHow to Inspect Your Foundation for Cracks

How to Inspect Your Foundation for Cracks

Complete checklist with climate-adjusted recommendations

Overview

Walk the perimeter looking for new cracks. Check basement walls for water stains or efflorescence.

DIY FriendlyEasy~30 min

Step-by-Step Guide

Walk the exterior perimeter

Walk slowly around the outside of your home, examining the visible foundation wall from ground level to the sill plate. Use a flashlight if shadows make it difficult to see. Look for new cracks, crumbling morite, gaps between the foundation and siding, and any areas where the soil has settled or pulled away from the wall.

Identify and classify crack types

Vertical hairline cracks (under 1/8 inch) are usually caused by concrete curing and are rarely structural. Horizontal cracks are more serious — they indicate lateral pressure from soil or water. Stair-step cracks in block foundations follow the mortar joints and suggest settling. Diagonal cracks from corners of windows or doors indicate point-load stress. Measure and photograph each crack.

Check for wall bowing or bulging

Stand at one corner of a foundation wall and sight along the surface toward the opposite corner. The wall should be flat and plumb. Any visible curve or lean inward (even 1/2 inch) indicates lateral pressure that may require professional stabilization. Use a 4-foot level held vertically against the wall to check for plumb.

Inspect interior basement walls

Examine the inside of foundation walls for water stains (brown or yellow discoloration), efflorescence (white crystalline deposits from mineral salts), and active moisture. Run your hand along the wall — dampness suggests water infiltration. Check the wall-floor joint where most water enters.

Check floors for cracks and heaving

Walk the basement floor looking for cracks, especially near the perimeter. Place a marble or ball on the floor in several locations — if it rolls consistently in one direction, the floor may be settling unevenly. Cracks wider than 1/4 inch or raised edges (heaving) may indicate hydrostatic pressure from below.

Examine windows, doors, and frame alignment

Check whether basement windows and doors open and close freely. Sticking or misaligned frames can indicate foundation movement. Upstairs, look for cracks above door frames and diagonal cracks in drywall radiating from window corners — these can be early signs of foundation settling.

Monitor existing cracks over time

For any crack you find, mark both ends with a pencil and write the date. Place a piece of clear tape across the widest point, or use an inexpensive crack monitor (adhesive card with grid lines, about $10). Check monthly — if the crack grows in length or width, it is active and needs professional evaluation.

What You'll Need

Tools

- Flashlight
- Tape measure
- 4-foot level
- Smartphone or camera
- Pencil or marker
- Crack monitor or clear tape

Cost Estimates

DIY Cost

$0–$10 (crack monitors)

Professional Cost

$300–$800 for a structural engineer inspection; $2,000–$15,000+ for foundation repairs depending on severity

Safety Tips

Wear a dust mask if your basement has visible mold or mildew.
Watch your footing in dark or cluttered basements — use a bright flashlight.
Do not disturb any asbestos-containing materials that may be present in older basements (white fibrous insulation on pipes).

When to Call a Professional

Call a structural engineer or foundation contractor if you find horizontal cracks, any crack wider than 1/4 inch, stair-step cracks that run most of the wall length, visible wall bowing or tilting, or if cracks are actively growing. Also call a pro if you see persistent water entry — waterproofing may be needed.

Pro Tip

Maintain proper grading around your foundation — the soil should slope away from the house at a rate of 6 inches over the first 10 feet. Poor grading is the number one cause of foundation water problems and is usually the cheapest fix.

Common Mistakes to Avoid

Panicking over normal concrete curing cracks — vertical hairline cracks (under 1/8 inch) are common and usually harmless.
Painting over efflorescence instead of addressing the moisture source behind it.
Ignoring grading and drainage issues that direct water toward the foundation.
Filling structural cracks with caulk instead of getting a professional assessment — caulk masks the problem without fixing it.
Not monitoring cracks over time to determine whether they are stable or growing.