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Sagging Floor Repair Cost: How Much to Replace? (2023)

Average National Cost
? All cost data throughout this article are collected using the RSMeans construction materials database.
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$1,000 - $10,000

Find costs near you.

Updated On

May 10, 2023

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Sagging floors can be an expensive repair, although the specific cost depends on what type of foundation you have and the severity of the underlying problem causing your floors to belly. The average cost to repair a sagging floor can range from as little as $1,000 to as much as $10,000, depending on what’s causing the problem. The only way to know for sure how much you’ll have to spend is to get an inspection and a quote from a professional.

This article provides information for identifying a sagging floor and diagnosing the root cause. We’ll also cover how to tell when you have a serious problem on your hand.

What Are the Signs of a Sagging Floor?

You might think that noticing a sagging floor would be easy, but a slight sag can be difficult to notice by eye. Here’s a table summarizing the most common signs of a sagging floor.

Signs of a Sagging Floor
Visibly sloped or tilting floors
Gaps between your floor and your baseboards
A noticeable bouncing when you walk on it
Doors or windows that are challenging to open or stick

Sloped or Tilting Floors

In severe cases, you might be able to tell that you have sagging floors simply by looking at them from an angle. If you can tell by eye that your floors are sloped, bellied, or tilted to one side, you need to contact a structural engineer immediately for an inspection. Drastically sloped floors are often a sign of foundation problems, so don’t hesitate to contact a professional and get the ball moving on a repair.

Gaps Between the Floors and Walls

A less obvious sign that you have sagging floors is a gap forming between your floors and baseboards. A sagging floor can sometimes pull away from the walls, leaving a noticeable gap at the bottom corner of the room. While this sign is slightly more subtle than a visibly sagging floor, it’s still associated with more severe structural issues and should be inspected and treated immediately.

Bouncy or Squeaky Floors

If you can’t detect any obvious visual signs that your floor is sagging, that doesn’t mean you’re in the clear. A slight bouncing sensation when you walk across the floor is a telltale sign of a sagging floor, although it can be hard to notice. If you think your floors feel springier than they used to, you should err on the side of caution and hire a foundation inspector or a repair contractor.

Additionally, depending on the type of flooring in your home, you might notice squeaking of the floorboards when you walk on them. This is uncommon in new flooring but can be a sign of serious damage in aging floors. This is especially true if you don’t have wood floors since the squeaking is then a result of joist movement. Check for squeaking floors if you have laminate, carpet, or vinyl flooring.

Hard to Open Doors or Windows

This sign is usually more common with bowing walls, but both issues can result from foundation damage and instability. Plus, sagging floors can put additional strain on door frames and window frames, making them more difficult to open.

If you notice your doors and windows becoming harder to open, check to see if you also have other symptoms of a sagging floor. If you only experience sticking windows and doors, it might just be from warping or frame expansion due to seasonal changes in weather and humidity and not a sign of a larger problem with your foundation or floor joists.

What Are the Possible Causes of Floor Sag?

Now that you know how to identify the most common signs of floor sag, let’s take a look at what causes a sagging floor in the first place. Many of these problems are more likely to crop up in an old house, but they can arise in any home, even in new construction.

Settling/Sinking Foundation

The most serious cause of sagging floors is a settling or sinking foundation, which is usually caused by shifting soil or poor soil quality. This problem can be extremely expensive to fix since it often requires complex foundation repairs involving excavation and the installation of additional supports.

If you have a slab foundation, a contractor can advise you whether or not mudjacking or hydraulic piers are appropriate solutions to fix the problem. Mudjacking is the more affordable option but doesn’t offer long-term results, while hydraulic piers are many times more expensive but offer rock-solid support for decades.

Depending on how severe the problem is, fixing sinking floors caused by a foundation issue can cost anywhere from $500 to $30,000.

Rotting Floor Joists

Another major issue that may cause sagging floors is rotting floor joists. Your home’s floors are supported by a network of thick support beams that can rot or decay with time from moisture exposure or termite activity.

You can sometimes identify this issue by inspecting your joints yourself if you have a crawlspace or a basement foundation. However, the only way to tell for sure if you have damaged floor joists is to schedule an inspection with a structural engineer. Replacing rotting joists usually costs between $2,000 and $6,000.

Water Damage

Water damage can affect your home’s foundation or supporting infrastructure by causing it to deform and warp. Extensive water damage can require a subfloor replacement or total hardwood floor replacement, which can get expensive depending on the extent of the damage and how many square feet your home is. The subfloor repair costs or replacement costs typically fall between $2,000 and $6,000 on average.


Termites strike fear into the heart of every homeowner, and for good reason. Termites can wreak havoc on your home’s wooden support structures, and a sagging floor could be a sign that they’ve been hard at work for a while. It’s hard to tell if termites are the cause of a sagging floor without taking a closer look, so you’ll have to get someone to do an inspection.

Whether you should schedule a pest control consultation or an engineering consultation depends on if you see other signs of termite activity throughout your home.

How Much Floor Sag is Acceptable?

Most building codes have guidelines for how much floor sag a structure can have before it’s considered a problem. The acceptable amount of sag is given as a fraction of the length of a room’s floor joists in linear feet and is usually 1/360 of the width. This is such a small level of sag that you won’t notice it by eye and can’t measure it with standard household equipment.

The bottom line is that if your floor is sagging enough for you to notice, it’s well beyond the acceptable limit.

How Do You Fix Sagging Floors?

Unfortunately, there isn’t one single way to fix a sagging floor because what needs to be done depends on what’s causing the sag. If your floor is sagging due to foundation issues, you might need to have it repaired, which can cost anywhere from a few thousand dollars up to tens of thousands of dollars.

Decaying floor joists can also cause sagging floors and requires a completely different type of repair than foundation-related issues. Whether a joist is damaged by water, termites, or a natural disaster, the process of fixing it is the same and usually requires total replacement. This involves installing temporary hydraulic jacks under your joists to lift your foundation and provide stability while the beam is replaced.

One of the most common and affordable ways to fix a floor joist is to join a second beam to it. This process is called sistering and is a relatively straightforward fix with good long-term results. Sister joists often last as long as a new joist, making it an affordable and cost-effective repair.

Should You Hire a Professional for Sagging Floor Repair?

A sagging floor is usually a pretty serious issue, and it’s often indicative of structural damage that requires professional repair. Although it might be tempting to save on labor costs, this type of repair should not be attempted as a DIY home improvement project.

Not only is it challenging and difficult to carry out these repairs safely, but it often requires expensive equipment that most homeowners won’t have access to, including house jacks and excavators.

In nearly every case, it’s a much better idea to hire a structural engineer to determine the underlying problem and then provide the results to a professional repair company for a structural repair.

How Long Does it Take to Repair Sagging Floors?

The timeline for your uneven floor repair depends on the extent of the damage, the type of foundation you have, and the specific repair that is required to fix the problem.

More severe damage often requires more extensive repairs in order to provide a suitable fix. If your sagging floors are a result of foundation damage, for example, you could be looking at several days’ worth of work to get the issue sorted out.

Sagging floor repairs on concrete slab foundations can also take the longest because there is no easy access to the underside of the home. Sinking floors in homes with slab foundations often require underpinning, which can take up to a week to implement. Flooring issues in crawlspaces and basements are a bit easier since access is more straightforward. Excavation might still be required, though, so you’re looking at one to two days or up to a week, depending on the severity.

Other Considerations?

Another important thing to consider is that sagging floors usually come with an underlying problem, so it’s not enough to treat the condition. If your floors are sagging because of foundation damage, it’s best to get the underlying issue fixed first before you address your floors.

In the case of termite damage, you should get a pest control company to install termite bait stations. In the case of foundation damage from soil expansion and contraction, you might need to have a drainage system put in place to fix the issue before reinforcing your foundation.

If your floor issue is a result of water damage, you might need to consider waterproofing your concrete foundation. Fixing a water issue can be expensive, but it’s the best way to avoid additional problems from popping up.

Another thing to consider is that your repair work might require permits. Something as simple as sistering a floor joist likely won’t need building permits, but large-scale foundation repair most certainly will. Permits won’t add much to your total project cost, but they can make the repair take a bit longer while you wait for approval and inspections.

Editorial Contributors
Dan Simms

Dan Simms


Dan Simms worked in real estate management for five years before using his experience to help property owners maintain their own homes. He got his master’s degree in English Literature and Creative Writing, and he now enjoys sharing his knowledge about homeownership and DIY projects with others on Today’s Homeowner. When he’s not writing, he’s usually outdoors with his wife and his dog, enjoying mountain biking, skiing, and hiking.

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Roxanne Downer


Roxanne Downer is a commerce editor at Today’s Homeowner, where she tackles everything from foundation repair to solar panel installation. She brings more than 15 years of writing and editing experience to bear in her meticulous approach to ensuring accurate, up-to-date, and engaging content. She’s previously edited for outlets including MSN, Architectural Digest, and Better Homes & Gardens. An alumna of the University of Pennsylvania, Roxanne is now an Oklahoma homeowner, DIY enthusiast, and the proud parent of a playful pug.

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