Is this crack serious?

Almost every house cracks somewhere. The question is whether this crack is just the house settling or a sign of movement that will keep going.

This page is mainly about cracks in walls, ceilings and foundation walls. For cracks in a concrete basement floor, see why is my basement floor cracking?

Possible causes

• Shrinkage and curing. New concrete and plaster shrink as they dry. One engineering page describes vertical foundation cracks as commonly caused by concrete shrinkage during curing. ^[1]
• Settling. A house moves slightly as soil compresses. Uneven settling can produce stair-step or diagonal cracks. ^[1]
• Soil moisture changes. Clay soils swell when wet and shrink when dry. Poor drainage, leaking pipes or tree roots can make soil move.
• Pressure on the wall. Wet soil pushing on a basement wall can cause horizontal cracks, which that source calls more serious than vertical ones. ^[1]
• Cosmetic causes in drywall and plaster. Seasonal movement, humidity and house settling often open cracks at corners, doors and windows.

How to identify the cause

Check width, direction, location and change over time.

Crack	Often means	What to do
Hairline, under about 1/16 inch	Normal settling or shrinkage; rarely a concern [1]	Seal if you want; keep an eye on it
Vertical, thin	Concrete shrinkage during curing; harmless unless wider than about 1/8 inch [1]	Monitor
1/8 to 1/4 inch	A moderate issue that deserves monitoring [1]	Measure and track; consider a professional look
Wider than 1/4 inch	Can signal significant structural problems needing prompt evaluation [1]	Call a structural engineer
Horizontal	More serious than vertical cracks [1]	Call a structural engineer
Stair-step in block or brick	Foundation settlement or movement [1]	Monitor closely, likely get a professional opinion
Fine surface web (crazing)	Surface-level only [1]	Cosmetic

Track it. Put a pencil mark at each end of the crack and write the date. Measure the width with a crack gauge or a ruler, and take a photo with a coin for scale. Check every few weeks and after heavy rain or dry spells. The same source lists a crack that grows by 1/8 inch or more in a month as a reason to call an engineer. ^[1]

Width cutoffs are not universal. This table follows one engineering page. Other sources draw the lines at slightly different widths, so use it as a sorting aid, not a rule.

How serious is it?

• Probably cosmeticThin cracks that are not growing, no water coming through, doors and windows still working.
• Watch and measureCracks about 1/8 to 1/4 inch, new cracks, stair-step patterns, or cracks that open and close with the seasons.
• Call a structural engineerCracks wider than 1/4 inch, any horizontal crack, a wall that bulges inward, several cracks forming a pattern, water constantly seeping in, or a crack that grows 1/8 inch or more in a month. ^[1]

If a basement wall is bowing or bulging inward, see Is my bowing basement wall serious? for how to measure it and what repairs cost.

Doors and windows that suddenly stick, sloping floors, or gaps opening between the wall and ceiling together with new cracks are also reasons to get a professional look.

What can you do?

1. Do not panic and do not rush to patch. A patch over a moving crack just cracks again. Measure first.
2. Fix the water. Clear gutters, extend downspouts, and make sure the soil slopes away from the foundation. Water is a common driver of soil movement.
3. Monitor for a few weeks if it is thin.
4. Hire a structural engineer (not a repair company) if it is on the worrying list. An engineer has no incentive to sell you a repair, and can tell you what is happening and what, if anything, to do. If you do get quotes from repair companies, get more than one.
5. Seal minor cracks once you are confident they are stable. A cosmetic repair is fine for drywall cracks and hairline foundation cracks.

Typical cost

These are ranges reported by the sources cited, not quotes. “Scope and date” is the geography the source covers and when it was published or last updated. Your price depends on your home, your area and the contractor.

The engineer’s report is often the best money spent, because it can save you from a repair you do not need, or confirm one you do.

Does fixing it affect property value?

“Return” is more than resale price. Where we have no reliable figure we say so instead of guessing. See how we think about value.

We have no reliable published figure on how much foundation cracks reduce value. In practice, an unexplained structural crack is something a buyer’s inspector will flag, and an engineer’s letter saying it is stable can reassure buyers. Keep the report, photos and any repair records.

Related tools

We do not have a calculator for this yet.

Deeper technical explanation

Why cracks form. Concrete is strong in compression and weak in tension. As it cures it shrinks, and the tension it cannot take shows up as a crack, usually vertical and often near corners or windows where stress concentrates. Foundations also move as the soil under them changes. If one part settles more than another, the wall racks, producing diagonal or stair-step cracks along mortar joints in masonry.

Horizontal cracks usually mean lateral pressure from soil and water against a basement wall. They are treated more seriously because they relate to the wall’s ability to resist that pressure.

Active vs. dormant. A crack that has stopped moving is a different problem from one that is still opening. That is why monitoring over weeks or seasons is so useful.

Limits. One consulting-engineer page is the source of the width cutoffs, and it is not a code or standard. Local soil, construction type and climate matter. This page is not a substitute for an in-person assessment.

Sources & methodology

Crack widths and patterns come from a consulting engineer’s guidance. Repair costs come from HomeGuide and are ranges. See how we work out costs.

1. Foundation Cracks in Homes and Buildings — Exactus Engineering Contractor or consultant explainerCrack-width thresholds and crack patterns. A single consulting-engineer page, not a standard; width cut-offs vary between sources. Accessed October 4, 2026.
2. Foundation Repair Cost — HomeGuide Cost guide (crowd/contractor data)Crack repair, leak repair and structural-engineer report costs. Updated Feb 2026. Scope: US national. Published or updated: Feb 2026. Accessed October 4, 2026.