How Much Does Floor Joist Repair and Replacement Cost? [2026 Data]

In 2026, the national average cost for floor joist repair is $6,000. Most homeowners pay between $4,000 and $12,000, depending on room size, the number of affected joists, and the severity of the damage. You should also budget for building permits ranging from $150 to $2,000, plus any additional costs for floor leveling or foundation repairs.

Floor Joist Repair Cost by Square Foot: Price Guide

Floor joist repairs typically cost $10 to $67 per square foot, depending on the extent of the damage, joist accessibility, and whether surrounding materials need replacement. Room size in square feet is a key driver of overall cost, as the breakdown below shows:

Floor Joist Repair Cost Factors: What Affects the Price?

Understanding what drives your floor joist repair cost starts with fixing sagging floors and evaluating the specifics of your project. The number of affected joists, the severity of the damage, and whether repair or full replacement is needed are the primary factors that shape your total price.

Size

Room size is one of the strongest predictors of floor joist repair cost, with full-room joist work running $10 to $67 per square foot. Minor repairs that allow you to reuse the original flooring sit at the lower end, while the higher end reflects more involved work such as jacking up the floor, sistering a joist, and replacing surrounding materials. Costs vary by room size, as shown in the table below.

Number of Joists

Repairing an individual joist with minimal damage costs $100 to $300 per joist, while a major repair can reach $1,000 per joist. Although labor makes up most of this cost, the joist material also matters, more expensive options like open-web floor trusses cost more to repair than traditional lumber.

Severity of Damage

Damage severity drives a wide cost range for floor joist repair, from sistering a slightly compromised joist at $100 to $300 per joist to full replacement work on rooms affected by termites or water damage costing $1,000 to $30,000 depending on square footage. Sistering involves adding a second joist directly alongside the original, making it the least invasive and most affordable repair option when the existing joist retains enough structural integrity.

Repair vs. Replacement

Joist repair is only an option when the existing joist is still strong enough to support a sistered beam. And while repairs will cost between $100 and $1,000 per joist, replacement costs between $1,000 and $2,000 per joist, including the cost of labor.

Accessibility

Flooring type, room location, and obstructions all affect how much labor is needed to reach damaged joists, which directly raises your repair cost. Joists beneath bathroom tile or complex plumbing require significantly more work to access than those in an open living room, and jacking up joists is easier in a basement than in a crawl space. Your contractor will factor all of these accessibility conditions into your estimate.

Labor

Labor for floor joist repair runs $65 to $100 per hour, and most projects take anywhere from 5 to 24 hours to complete. When deciding who to hire to repair a floor joist, you will most likely need a highly qualified floor contractor or structural engineer.

Permits

Altering load-bearing structural elements almost always requires a building permit, so budget accordingly before work begins. Permits cost $150 to $2,000 for construction projects and around $200 for demolition.

Floor Joist Repair Costs by Layer: What to Budget For

When flooding causes rot or mold, repairs may extend beyond the joists to include the subfloor and top floor layer, though in unfinished basements where joists are visible overhead, you may only need to pay $100 to $300 per joist. Costs vary by floor layer, as the breakdown below shows.

Floor Covering

The floor covering is your top layer, typically carpeting, ceramic tile, hardwood plank, vinyl, or laminate, and repair costs range from $130 to $2,300 per room or $2 to $30 per square foot depending on the material. Full replacement runs $800 to $10,000 or more per room based on your chosen install type.

Underlayment

Underlayment is an optional layer that addresses squeaky floors, under-floor heating, or leveling needs, and installation costs $0.50 to $5 per square foot.

Subflooring

The subfloor is the plywood surface that sits between your floor covering and the joists, and repairs cost $500 to $700 per room or $2 to $10 per square foot. Full subfloor replacement runs $1,800 to $3,000 per room.

Joists

Repairing the long beams that provide main structural support costs $200 to $500 per room or $10 to $67 per square foot, while a full joist replacement runs $5,000 to $20,000. If only individual joists need attention, expect to pay $100 to $300 per joist.

Floor Joist Costs by Type: Which Material Fits Your Budget?

Floor joists come in several wood and metal-reinforced types, and while labor makes up the majority of repair costs, your choice of material will also influence the final price. Costs vary by joist type, as the breakdown below shows.

Engineered Floor Joists

Engineered floor joists are constructed from plywood, OSB (oriented strand board), particle board, or fiberboard sandwiched between standard lumber, and a 16-foot engineered I-beam averages $40. Beam-shaped or truss-type engineered joists can span greater distances than traditional lumber with little to no sagging over time, making them a durable long-term option.

2x10 Joists

2x10 softwood lumber joists are the most popular choice for floor joists, averaging $30 for a 16-foot board, and they are easier to cut and manipulate than engineered options. However, because 2x10s do not come in lengths that span an entire home, you will often need to purchase twice as many as you would I-beams, which can raise your overall installation cost. They also tend to warp or bow over time due to their natural wood construction.

Open-Web Truss Joists

Open-web truss joists use triangles of wood or metal between two wood beams to create a more secure structure, costing $30 to $70 per joist. The double-tiered design prevents bowing over time and makes it easier to route wiring and plumbing through the floor without compromising the joist structure.

Floor Joist Additional Costs: What Other Expenses Should You Plan For?

A floor joist repair can expand into a larger project once contractors tear up flooring and subflooring to access the damage, and in many cases homeowners choose to replace the floor entirely while the work is already underway.

Floor Leveling

Leveling an uneven floor typically costs $1,000 to $20,000 depending on the underlying cause of the bow. Beyond joist repair itself, contractors may also need to use mudjacking or support beams to fully level the foundation and floors.

Floor Replacement

Replacing the floor above the joists is one of the most common add-ons to a joist repair project, with new flooring installation costs averaging $12.50 per square foot and ranging from $2 to $22 per square foot, with the cost of hardwood floors at the high end. Your final price will also reflect the cost to demolish whatever material sat on top of the joists before installation.

Subflooring Replacement

The subfloor sits between your finished floor layer and the joists, and is typically made of plywood, engineered wood, or concrete. Replacing subfloors costs $3 to $10 per square foot or about $1,600 for the average room.

Foundation Repair

Cracked joists are sometimes caused by a damaged foundation, and the cost of foundation repairs averages $5,000 depending on the culprit. Simple crack repairs can cost as little as $250, while underpinning runs $1,000 to $3,000 per pier.

Structural Repairs

Structural elements surrounding the joists may also need attention beyond the foundation itself. Replacing a sill plate averages $22,000 because contractors must raise the home to complete the work, and if the main support beam has also been compromised, replacing the beam costs an average of $3,300.

Pest Abatement

Termite infestations are a common root cause of floor joist damage, and the cost of termite treatment averages about $600, though major abatements can reach $2,500 for a home, not including the cost of repairing the structural damage termites leave behind.

Why You Should Hire a Floor Joist Repair Pro

While a successful DIY floor joist repair can save $65 to $100 per hour in labor costs, floor joists are load-bearing and mistakes can snowball into major structural damage. A local flooring repair contractor can handle jacking, sistering, and full replacements, plus they can navigate accessibility challenges and pull the required permits to ensure a job that's safe, thorough, and up to code.

Here's why it's ideal to hire a floor joist repair pro

Floor joist repair often isn't straightforward to the untrained eye. Here's why it's best to invest in professional repair service:

• Professional floor repair contractors can safely jack floors, sister joists, or replace them entirely without creating new structural issues.

• Pros assess the scope by room size and number of joists, then choose whether repairs or replacement will be the best option.

• Contractors can safely work around accessibility issues, such as tile, plumbing, and crawl spaces.

If you want to DIY floor joist repair

If you're still looking for a potential DIY to save on labor, consider these tips:

• Start by investing $300 to $500 for a professional inspection to gauge the nature and extent of repairs needed.

• Tackle minor sistering (adhering and nailing new joists alongside the damaged ones) to remedy slight sagging or bouncing. Materials cost $100 to $300 but may require a hydraulic jack.

• Gather any spare flooring materials to save on material costs.

Ways to Save Money on Floor Joist Repair and Replacement

If you're experiencing sticker shock at the cost of floor joist repairs, there are ways you can keep them down. And while it may be tempting to cut costs by doing the repair yourself, there are safer ways to save money if you're not comfortable handling this without a professional.

1. Meet with at least three local general contractors or floor specialists to compare estimates and repair options.

2. Reuse the original flooring materials whenever possible.

3. Address the cause of the issue to avoid costly joist repairs in the future.

4. Keep a flexible schedule and timeline to avoid pricing surges on materials.

5. Tackle several flooring issues at once to cut down on demolition and labor costs.

6. Hire a structural engineer or inspector to provide an expert analysis of the work before hiring a contractor.

7. Inspect and repair floor joists at the first signs of damage.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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