Basement crack repair: $250 to $800 a crack, what it means

Basement crack repair cost

National figures. HomeGuide groups hairline, vertical and diagonal cracks as non-structural and horizontal and stair-step cracks as structural.

Sealing a crack costs $250 to $800 per crack in HomeGuide's, Angi's and This Old House's figures. HomeGuide prices structural cracks separately: $1,000 to $5,000 or more for minor horizontal or stair-step cracks and $10,000 to $30,000 or more for major ones, because the fix is anchors, straps, tiebacks or piers rather than filler. Which group a crack belongs in depends on its pattern more than its size, and that is what this page is about. A crack or a damp wall is a reason to get it looked at, not proof that the house is failing: the ASCE Texas Section guideline says "the majority of cracks do not compromise structural integrity."

Do this now: read the crack before you call

1. Note the direction. Vertical, diagonal, horizontal, or stepping along the mortar joints of block or brick. Direction is the first thing an engineer looks at.
2. Measure the width at its widest and at each end. HomeGuide treats cracks under 1/8 inch as often cosmetic and flags cracks wider than 1/8 inch and horizontal cracks longer than 12 inches; This Old House's threshold for calling a structural engineer is 1/4 inch. A crack that is wider at one end than the other tells its own story (below).
3. Mark the ends and date them. Pencil lines at each end and across the crack. If the marks move or the crack opens over a season, that is the fact a structural engineer wants.
4. Check for water and for a bulge. Hold a straightedge or a level against the wall. A wall that is no longer flat at the crack is the sign that separates a surface crack from a loading crack (Forcon).
5. Look outside at that spot. A downspout, a tree, a sunken bed or a patio that drains toward the wall usually sits right behind a crack. UMN Extension's grading and downspout rules are on the basement waterproofing page.

Is it urgent? The cracks engineers flag

Two patterns get flagged by engineers for prompt investigation. A horizontal crack along the middle height of a basement wall, with the wall bowing inward, comes from lateral soil pressure, often saturated soil; Forcon's structural engineer writes that "cracks of this type are a cause for immediate concern and should be investigated for cause and repair." A wall that is visibly leaning or out of plumb, or a crack that has opened noticeably after heavy rain or a freeze, belongs in the same group. Water coming through a crack is a reason to act in days; see basement leak repair. Everything else is a measure-and-watch problem that can wait for an inspection within a few weeks.

What each crack type usually means

Hairline and shrinkage cracks

Thin cracks that run near-vertical in poured concrete, often mid-span of a long wall or above a window or door, with roughly the same width top to bottom, are shrinkage cracks. Forcon's engineering guide says they are "usually caused by an inadequate number of control or contraction joints," too much water in the mix, or green masonry; This Old House says they form as concrete cures and shrinks and are typically cosmetic, worth monitoring if they widen, return after repair or let in moisture. What a contractor or engineer would check: whether it leaks and whether it has grown. The fix, if any, is injection at $250 to $800.

Vertical cracks

Vertical cracks in a poured wall are often tied to normal settling and are the least worrying group in This Old House's guide. Forcon lists two exceptions: a vertical crack at the end of a wall that is tight at top and bottom but opens at mid-height, from a concentrated load above, and a vertical mid-wall crack wider at the top with the upper wall bowing inward, from soil pressure where the top of the wall is not well supported. Both are loading cracks. The check is simple: is the wall still flat across the crack, and is the crack wider at one end?

Diagonal cracks

A diagonal crack that starts near a corner at the top and runs down and away, wider at the top and closing at the bottom, is a settlement crack in Forcon's guide: the corner has dropped, often from erosion under it or a concentrated load the footing was not designed for. The reverse, wider at the bottom near a corner, means the corner is held up while the middle settles. Level Engineering adds a third diagonal pattern, running from the top down after the connection between the wall and the floor framing fails, with the top of the wall moving inward. This Old House says diagonal cracks alone do not always mean a major problem but warrant evaluation together with sticking doors, sloping floors or gaps. An engineer would survey floor elevations and look at what is under that corner.

Horizontal cracks

A horizontal crack at mid-height is the pattern every source treats differently from the rest. This Old House: horizontal cracks "indicate that the soil is exerting enough pressure on the wall to make it bulge inward." Forcon: caused by lateral pressure, often saturated soil on a basement wall, exceeding the wall's strength, with the crack wider on the inside face and the wall bowed in at mid-height. Level Engineering: the wall itself is not strong enough for the load, so it bends. The fixes are the bowing-wall fixes, priced on bowing basement walls: straps, anchors, tiebacks or straightening, plus drainage so the soil stops pushing. HomeGuide's structural range of $1,000 to $5,000 minor and $10,000 to $30,000 major applies here.

Stair-step cracks in block or brick

Block and brick crack along the mortar joints, so almost every crack in masonry looks like stairs; the question is why. Forcon says shrinkage cracks in masonry follow the joints in a stair-step with uniform width, while settlement cracks are stair-step diagonals that are wider at one end, mid-wall ones wider at the base. A stair-step crack that also runs horizontally along one course at mid-height is the masonry version of the horizontal crack above. HomeGuide prices stair-step cracks with the structural group. An engineer would measure the widths along the crack, check whether the wall is plumb and look at the footing below.

How cracks get repaired

• Epoxy or polyurethane injection, $250 to $800 per crack. This Old House says injection seals narrow cracks and keeps water out but does not address ongoing movement. The ASCE Texas Section guideline uses epoxy on slab cracks of about 1/32 inch and larger to restore stiffness, and says sealants may be enough if the goal is only keeping moisture or insects out.
• Carbon fiber strips, $900 to $2,000 per crack (HomeGuide), and wall anchors, $500 to $1,000 each. These hold a wall that is bowing; This Old House notes they are usually part of a larger plan that includes drainage or soil work.
• Helical tiebacks, $1,000 to $3,000 each, and piers, $1,000 to $3,000 each (Angi, This Old House). Tiebacks pull a wall back; piers support a footing that has settled. See foundation underpinning.
• Drainage. Most horizontal cracks come with a water problem. UMN Extension's order is grading and downspouts first, then an interior or exterior drain; see French drain cost.

Who should look at it

A foundation repair company's inspection is often free and a structural engineer's report costs $300 to $1,000 (Angi) or $500 to $1,000 (This Old House). HomeGuide notes that companies offering free inspections may be more likely to recommend repairs. For a horizontal crack, a leaning wall or a diagonal crack with sloping floors, the engineer's report is the one that tells you what the repair has to do; for a single leaking vertical crack, a contractor's injection quote is usually enough. Foundation inspection cost goes through the difference. Texas has no state license for foundation repair: a 2011 bill that would have created one (S.B. 1399) said at the time that "there is no state regulation in place to directly mitigate these risks," and the Texas Department of Licensing and Regulation's list of 41 regulated industries still has no foundation repair program. Other states differ, so check your own state's contractor board, ask for the license number if your state issues one, and ask for proof of insurance either way.

Insurance and the local pages

Standard homeowners policies exclude flood, earthquake, landslide and sinkhole damage and damage from lack of maintenance (Triple-I), and the Maryland Insurance Administration says water that seeps in through a foundation wall or floor is treated as a maintenance issue and generally not covered. A burst pipe is the usual exception. Does homeowners insurance cover home repairs covers the lines. City pages: San Antonio, Fort Worth, Dallas, Kansas City, Houston; basement waterproofing in Chicago, Columbus, Indianapolis, St. Louis. Calls go to an independent company that serves your area and takes this kind of job; hours vary. How calls work.