How Much Does Floor Joist Repair and Replacement Cost? [2024 Data]
Normal range: $4,000 - $12,000
Floor joist repair costs between $1,000 and $20,000, or an average of $6,000, depending on the extent of the damage and the size of your room.
Floor joist repair costs between $1,000 and $20,000, or an average of $6,000, depending on the extent of the damage and the size of your room. The typical cost to repair joists and other parts of your flooring is $10 to $67 per square foot.
Uneven, sagging, or rotting floors are all signs of a damaged floor joist—the long beams under your floors that support the weight of your home. The price of floor joist repair is often part of a larger picture when calculating floor repair costs.
- Average
- $6,000
- Low end
- $1,000
- high end
- $20,000
How Much Does It Cost to Repair a Floor Joist per Square Foot?
Joist repairs tend to run $10 to $67 per square foot, depending on the extent of the damage, the accessibility of the joists, and whether you also need to replace the surrounding materials. Between materials and labor, structural repairs to your flooring overall run $40 to $60 per square foot. You may spend more than $20,000 if all the flooring in a 300-square-foot room needs to be replaced.
Floor Joist Repair Cost Factors
The first step to fixing sagging floors, and determining the true cost of floor joist repair, is to break down the details of your project. The number of affected joists, the severity of the damage, and whether or not you simply need to replace the joist will all contribute to your total price.
Size
The size of your room will heavily determine the price of floor joist repair. If you need to replace all of the joists in one space, you'll pay anywhere from $10 and $67 per square foot—quite a wide range. The lower end of the price range accounts for minor repairs to joists that allow you to reuse the original flooring. The higher end of the cost incorporates jacking up the floor for support, sistering a joist, and replacing surrounding materials.
Floor Joist Repair Cost by Room Size
| Room Size in Square Feet | Low End | High End |
|---|---|---|
| 100 | $1,000 | $6,700 |
| 150 | $1,500 | $10,050 |
| 300 | $3,000 | $20,100 |
| 350 | $3,500 | $23,450 |
| 500 | $5,000 | $33,500 |
Number of Joists
Individual joist repairs that have minimal damage, and are easily accessible, will cost $100-$300 per joist to repair, or up-to $1,000 per joist for a major repair. And while most of this cost is the cost of labor, the type of joist also plays a role. More expensive materials, such as open-web floor trusses, cost more than traditional lumber to repair.
Severity of Damage
Joist repair costs cover everything from a slightly compromised joist to one that requires total replacement. In some cases, you or a contractor will be able to sister the joist by adding a second joist directly to the original one. The sistering process can cost as little as $100 to $300 per joist.
On the other side of the spectrum, rooms affected by termites or water damage may require a range of repairs or complete replacement. Severe damage will cost between $1,000 and $30,000, depending on the square footage.
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
The type of flooring, the location of the room, and common obstructions can raise the cost of floor joist repairs. For example, damaged floor joists below bathroom tiles and under complex plumbing require more labor to access than those located in the middle of a living room. Additionally, if your floor joists need to be jacked up for support, access in a basement will be more straightforward than a crawl space. Your contractor will take all of these factors into account when compiling your estimate.
Labor
You have several options when deciding who to hire to repair a floor joist, though you will likely need a highly-qualified floor contractor or structural engineer. When repairing hardwood floor joists, expect to pay $65 to $100 per hour on labor alone. This project tends to take anywhere from 5 to 24 hours to complete.
Permits
Altering load-bearing and structural elements in your home almost always requires a building permit. Permits cost anywhere from $150 to $2,000 for construction projects and around $200 for demolition.
Cost Breakdown to Repair Floors by Layer
If the joists were damaged by rot or mold caused by flooding, repairs or replacements may need to be done to the entire floor, including the top layer and subfloor. In unfinished basements where first floor joists are visible overhead, you’ll likely only need to pay $100 to $300 per joist.
We break down each layer and the associated installation costs for each layer below.
Floor Covering
This is your top layer that usually consists of carpeting, ceramic tile, hardwood plank, vinyl, or laminate. Repair costs $130 to $2,300 to install per room or $2 to $30 per square foot, depending on the type of flooring you own. Full replacement costs $800 to $10,000 or more per room, depending on your install type.
Underlayment
An optional layer installed to help with squeaky floors, under-floor heating, or leveling, underlayment installation costs $0.50 to $5 per square foot.
Subflooring
Under your floor covering is a surface, usually of plywood, that covers your joists. Subfloor repair costs $500 to $700 per room or $2 to $10 per square foot. Full subfloor replacement costs $1,800 to $3,000 per room.
Joists
The long beams that provide the main structural support for the floor can cost $200 to $500 per room or $10 to $67 per square foot to repair. A full replacement costs $5,000 to $20,000. If you’re only repairing individual joists, expect to pay $100 to $300 per joist.
How Much Do Floor Joists Cost by Type?
Floor joists use several types of wood and metal reinforcement. While most of the floor joist repair cost is labor, the materials you choose will also sway your price.
Engineered floor joists
Engineered floor joists are made from plywood, OSB (orientated strand board), particle, or fiberboard between standard lumber. Beam-shaped or truss-type engineered joists can span greater distances with little to no sagging over time. On average, you’ll pay $40 for a 16 foot engineered I-beam.
2x10 joists
2x10 joists of softwood lumber reign as the most popular choice for floor joists due to their lower cost and their ability to be cut according to length. While 2x10s are easier to cut and manipulate than engineered floor joists, they tend to warp or bow over time due to their natural wood construction.
On average, you’ll pay $30 for a 16’ 2x10. Keep in mind that 2x10s do not come in sizes that span the entire length of an average home, so you’ll often need to purchase twice as many joists as you would I-beams. This can increase your overall installation cost.
Open-Web Truss Joists
Open-web truss joists place triangles of wood or metal between two wood beams to make a more secure joist, and cost between $30 and $70 per joist. The double-tiered structure offers extra support to the floors and prevents bowing over time. It also makes it easier to incorporate wiring and plumbing into the floor without interrupting the structure of the joists.
Common Add-Ons
As we mentioned above, what starts as a floor joist repair may come to involve tearing up your flooring and subflooring to access any problems. If that’s the case, you may wish to replace your floor completely as part of the project.
Floor Leveling
Leveling an uneven floor typically costs between $1,000 and $20,000, depending on the problem causing the floor to bow. In addition to floor joist repair, contractors may need to use mudjacking or support beams to level the foundation and floors.
Floor Replacement
Replacing the floor above the joists is one of the most common additional repairs. New flooring installation costs an average of $12.50 per square foot, or anywhere from $2 to $22 per square foot, with the cost of hardwood floors on the high end. Prices will vary depending on the new materials as well as the cost to demolish what sat on top of the joists in the first place.
Subflooring Replacement
Between your floor's finishing later and the joists, you'll find the subfloor. Typically made of plywood, engineered wood, or concrete, replacing subfloors costs between $3 and $10 per square foot or about $1,600 for the average room.
Foundation Repair
Cracked joists are occasionally the work of a damaged foundation. You'll need to budget an average of $5,000 for the cost of foundation repairs depending on the culprit. Cracks can cost as little as $250 to repair whereas underpinning ranges from $1,000 to $3,000 per pier.
Structural Repairs
In addition to the foundation itself, structural elements surrounding floor joists may have been affected. Replacing a sill plate costs an average of $22,000—primarily because contractors need to raise your home to do it. If the main support beam of a house has been compromised as well, replacing the beam costs an average of $3,300.
Pest Abatement
Termite infestations could be at the heart of your floor joist issues. The cost of termite treatment averages about $600, but major abatements can cost up to $2,500 for a home, not including the related damage they may cause.
Cost to Repair Floor Joists Yourself
Before taking on any DIY repairs to the structure of your floors, have a contractor inspect them for structural issues like rot, mold, undersized joints, or added weight from a heavy object. An inspection can cost $300 to $500. These issues often require professional work, for which you’ll get a scope and a cost estimate.
Occasionally, you can remedy slight sagging or bouncing problems in one or a few joists through a process called sistering. The job involves adhering and nailing new joists alongside the damaged ones and may require a hydraulic jack to level the structure. Expect materials to cost $100 to $300.
If there are electrical cables, plumbing pipes, and other obstructions that make it difficult to access the damaged joist, or if you don’t have the proper tools or knowledge to do the job yourself, your best option is to hire a contractor. If you improperly address problems with your floor joists, it can lead to more severe and costly structural damage throughout your home.
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.
Meet with at least three local general contractors or floor specialists to compare estimates and repair options.
Reuse the original flooring materials whenever possible.
Address the cause of the issue to avoid costly joist repairs in the future.
Keep a flexible schedule and timeline to avoid pricing surges on materials.
Tackle several flooring issues at once to cut down on demolition and labor costs.
Hire a structural engineer or inspector to provide an expert analysis of the work before hiring a contractor.
Inspect and repair floor joists at the first signs of damage.
Frequently Asked Questions
Many homeowners will choose to hire a contractor to handle the work. However, you can take some DIY steps if a single joist is cracked or multiple joists are undersized but in otherwise good shape. On a basic level, you will need to jack up your floor from below and add a supportive beam to the joist in question. Once attached, you will be able to repair the joist by sistering it with a second piece of wood. Keep in mind that these repairs typically require a structural engineer and a permit to proceed.
A general contractor should have no problem repairing your floor joists, but structural engineers and floor contractors also do this work. Before you hire the best professional for you, ask family, friends, and neighbors for recommendations for who to work with or who to avoid. You should request at least three estimates from different contractors, and ask each one to provide recent references. Your contractor should provide a budget and estimated timeline for the work, as well as their plan to pull permits and arrange inspections if necessary.
Sagging floors, large cracks in your walls, and uneven door frames are three signs that your floor joists need to be replaced. You may also notice squeaky floorboards, windows that no longer close correctly, and stairs that sag on either side. You'll need a structural engineer or floor contractor to confirm whether the floor joists are the true problem behind these issues.