Foundation repair: signs, methods, costs, and how to act

Foundation problems are among the most stressful issues a homeowner can face. The good news is that most foundation issues are repairable, and catching them early saves money and prevents the damage from spreading.

This guide walks you through the warning signs, common causes, repair methods, typical costs, and how to choose a qualified contractor. The goal is to help you understand what you are dealing with so you can take the right action at the right time.

Signs of foundation problems

Foundation damage rarely appears overnight. It develops gradually, and the warning signs often show up in other parts of your home before you notice anything on the foundation itself.

Cracks in walls and ceilings

Interior cracks are the most common early sign. Look for:

• Diagonal cracks running from the corners of doors and windows toward the ceiling
• Stair-step cracks in brick or block walls (following the mortar joints)
• Horizontal cracks in basement walls
• Cracks where walls meet ceilings or floors

Hairline cracks less than 1/8 inch wide are usually cosmetic and result from normal settling. Cracks wider than 1/4 inch, cracks that are growing, or horizontal cracks in basement walls indicate structural movement that requires professional attention.

Sticking doors and windows

When a foundation shifts, door and window frames go out of square. Doors that suddenly stick, will not latch, or swing open on their own are classic symptoms. Windows that become difficult to open or close point to the same issue.

One sticking door may just be humidity. Multiple doors and windows with new problems suggest foundation movement.

Uneven or sloping floors

Place a ball on the floor. If it rolls to one side consistently, your floor may be sloping due to foundation settlement. Some slope is normal in older homes, but new or increasing slope is a concern.

Bouncy or sagging floors can indicate deteriorating support beams or piers beneath the floor, which is a related but different problem from slab foundation issues.

Gaps and separations

Foundation movement creates gaps between:

• Walls and ceilings
• Walls and floors
• Exterior walls at corners
• Chimney and the house structure

These gaps tend to appear gradually and widen over time if the underlying cause is not addressed.

Exterior warning signs

Walk around the outside of your home and look for:

• Cracks in the foundation wall itself (visible above ground)
• Gaps between the foundation and siding
• A leaning chimney
• Gaps around doors and garage openings
• Bowing or bulging foundation walls

Types of foundation issues

Understanding what is happening beneath your home helps you evaluate repair proposals and costs.

Settling

The most common issue. Settling occurs when the soil beneath the foundation compresses or shifts, causing part of the structure to sink. It is especially common in areas with expansive clay soils that shrink during dry periods.

Settling can be uniform (the entire house sinks evenly, causing fewer visible symptoms) or differential (one side sinks more than the other, causing cracks, sloping floors, and sticking doors).

Heaving

The opposite of settling. Heaving occurs when soil beneath the foundation expands, pushing the slab upward. Expansive clay soils that absorb moisture are the most common cause. Frost heave in cold climates can produce similar effects.

Heaving is most common after periods of heavy rain or when plumbing leaks saturate the soil beneath the slab.

Lateral movement

Basement and retaining walls can bow inward from hydrostatic pressure, which is the force of water-saturated soil pressing against the wall. Horizontal cracks and inward bowing are the telltale signs.

Lateral movement is a serious structural concern and should be addressed promptly. Walls that have moved more than 2 inches inward may require significant reinforcement or replacement.

Water damage

Water is the single biggest enemy of foundations. Persistent moisture against the foundation causes:

• Erosion of the soil supporting the foundation
• Hydrostatic pressure on basement walls
• Deterioration of concrete and morite joints
• Mold and mildew in crawl spaces and basements

Poor grading, clogged gutters, missing downspout extensions, and failed sump pumps are the most common culprits.

Repair methods

The right repair method depends on the type and severity of the problem. A reputable foundation contractor will explain why they recommend a particular approach for your situation.

Piering (underpinning)

Piering is the standard solution for settling foundations. Steel piers are driven through the unstable soil until they reach load-bearing strata (solid rock or stable soil). Hydraulic jacks attached to the piers then lift the foundation back to its original position.

Types of piers:

• Push piers. Steel pipe sections are hydraulically driven into the ground using the weight of the structure. Best for moderate to heavy structures.
• Helical piers. Screw-like steel shafts are rotated into the ground. Best for lighter structures, new construction, and situations where the bearing stratum is shallow.

Cost: $1,000 to $3,000 per pier. Most homes require 6 to 12 piers, putting the total at $6,000 to $15,000 or more.

When it is used: Settling, sinking, or tilting foundations.

Slabjacking (mudjacking and polyurethane foam)

Slabjacking lifts a sunken concrete slab by pumping material through holes drilled in the surface. Two methods are available.

Mudjacking pumps a cement-based slurry beneath the slab. It is the more affordable option at $500 to $1,500 for most residential jobs but adds significant weight.

Polyurethane foam injection pumps expanding foam beneath the slab. It is lighter, cures faster (15 minutes vs 24 hours), and is more precise, but costs $1,000 to $3,000.

When it is used: Sunken or uneven slabs (driveways, garage floors, patios, sidewalks) and minor slab foundation settlement.

Wall anchors and braces

Wall anchors stabilize bowing basement walls by connecting them to anchors embedded in the stable soil beyond the foundation. A steel plate is installed on the interior wall, connected by a rod to an anchor plate buried several feet into the yard.

Carbon fiber strips are an alternative for less severe bowing. They bond to the wall surface and resist further movement.

Cost: $500 to $1,000 per anchor. Most walls require 3 to 5 anchors, totaling $1,500 to $5,000.

When it is used: Bowing or leaning basement walls caused by lateral soil pressure.

Drainage correction

Many foundation problems are caused or worsened by poor drainage. Correcting drainage is often done alongside structural repairs to address the root cause.

Common drainage solutions include:

• French drains around the foundation perimeter ($1,000 to $4,000)
• Interior drain tile systems with a sump pump ($2,000 to $6,000)
• Regrading the soil around the foundation to direct water away ($500 to $2,000)
• Downspout extensions and gutter repairs ($200 to $800)

Sealing and waterproofing

Foundation cracks that allow water entry need sealing even if they are not structurally significant. Methods include:

• Epoxy injection for structural crack repair ($300 to $600 per crack)
• Polyurethane injection for non-structural, water-stopping repairs ($200 to $500 per crack)
• Exterior waterproofing membrane applied to the outside of the foundation wall ($5,000 to $15,000 for full perimeter)

Cost by repair type

Here is a summary of typical foundation repair costs.

The national average for a foundation repair project is roughly $5,000. Minor repairs may cost as little as $500. Major structural stabilization with piering can exceed $15,000.

How to choose a foundation contractor

Foundation repair is specialized work. The wrong diagnosis or improper repair can make problems worse and cost you more in the long run.

Start with an independent assessment

Before getting repair quotes, consider hiring a licensed structural engineer for an independent evaluation. Engineers charge $300 to $800 for a foundation assessment and provide an unbiased report on the type and severity of the problem, along with recommended repair methods.

This report becomes your baseline for evaluating contractor proposals. If a repair company recommends significantly more work than the engineer, ask them to explain the discrepancy.

What to look for in a contractor

• Licensing and insurance. Verify the contractor holds appropriate licenses for your state and carries general liability and workers’ compensation insurance.
• Foundation-specific experience. General contractors may not have the specialized knowledge required. Look for companies that focus on foundation repair.
• Warranty. Reputable foundation companies offer transferable warranties of 25 years to lifetime on structural repairs. The warranty should cover the repair itself, not just materials.
• References. Ask for references from recent projects with similar issues. Foundation work is highly specialized, and experience with your specific problem type matters.

For more detailed guidance, see our guide to hiring a concrete contractor.

Red flags

• Quotes without an on-site inspection
• High-pressure sales tactics or “today only” pricing
• No written warranty or non-transferable warranty
• Unable to explain the cause of the problem, only the proposed fix
• Significantly lower price than all other quotes (may indicate shortcuts)

When to act vs when to monitor

Not every crack means you need to call a contractor today. Here is how to decide.

Act now

• Horizontal cracks in basement walls
• Stair-step cracks wider than 1/4 inch
• Visibly bowing or leaning walls
• Active water intrusion through the foundation
• Floors sloping noticeably in one direction
• Multiple doors and windows sticking or not closing

Monitor and reassess

• Hairline cracks (less than 1/8 inch) that are not growing
• A single sticking door (may be humidity-related)
• Minor cosmetic cracks around windows
• Small efflorescence (white mineral deposits) on basement walls

How to monitor cracks: Mark the ends of each crack with a pencil and write the date. Measure the width at the widest point. Check monthly. If a crack grows in length or width over 3 to 6 months, schedule a professional assessment.

For all foundation concerns, getting an expert opinion earlier is better than waiting. Many foundation companies and structural engineers offer free or low-cost initial consultations. The cost of an assessment is negligible compared to the cost of damage that worsens over time.

Foundation problems by region

Foundation issues are driven by local soil conditions. Here is what homeowners face in our covered markets.

Expansive clay soil states. Salt Lake City, Denver, Charlotte, Raleigh, Nashville, and Columbus all sit on clay soils that expand and contract with moisture changes. This is the most common cause of residential foundation problems nationwide. Proper drainage around the foundation, consistent moisture levels, and avoiding large trees too close to the house all reduce foundation stress.

Sandy soil states. Tampa and other Florida locations have sandy soil that can settle unevenly, causing one side of a foundation to sink. The high water table adds hydrostatic pressure against basement walls and slabs.

Caliche soil. Phoenix homeowners rarely have traditional settling problems because caliche provides a solid bearing surface. However, caliche does not drain well, and water pooling around foundations during monsoon season can cause localized erosion.

Limestone bedrock. Nashville sits on limestone that provides excellent support but creates challenges when the clay layer above it shifts. The combination can cause differential settlement where some areas of the foundation are on rock and others are on shifting clay.

Wet climate states. Portland and other Pacific Northwest locations deal with persistent moisture that can erode soil supporting the foundation. Seismic activity in Oregon adds another risk factor for foundation damage.

Expert tips for foundation concerns

Fix drainage first. Many foundation problems are caused or worsened by poor drainage. Before investing in structural repairs, make sure your gutters are clean, downspouts extend at least 6 feet from the foundation, and the ground slopes away from the house at a rate of 6 inches over the first 10 feet.

Get an independent assessment. A structural engineer’s evaluation ($300 to $800) gives you an unbiased diagnosis. Foundation repair companies offer free inspections but may recommend more work than necessary. The engineer’s report protects you from being oversold.

Do not panic over hairline cracks. Small cracks less than 1/8 inch wide are normal in most homes. Monitor them with pencil marks and measurements before calling a contractor. Cracks that grow or widen over a few months warrant professional attention.

Transferable warranties matter. If you plan to sell your home, a transferable warranty on foundation repair work protects the next owner and preserves your home’s value. Most reputable foundation companies offer 25-year to lifetime transferable warranties.

If your foundation repair requires financing, our home improvement financing guide covers loan options for major home repairs.

For more on concrete and foundation services, visit our concrete services hub. Learn how to hire a concrete contractor for your foundation project.