Fixing a sagging floor can cost anywhere from $1,000 for minor repairs to $10,000 or more for severe structural damage. The total cost depends on what’s causing the sag — whether it’s foundation settlement, rotting floor joists, or water damage. If the problem is caught early, repairs can be relatively affordable, but ignoring the issue can lead to more extensive damage and higher costs.
Sagging floors can signal serious foundation problems, which is why it’s essential to schedule an inspection as soon as you notice sloping, bouncing, or gaps forming between the floor and baseboards. In this guide, we’ll break down the most common causes of floor sag, explain how to spot early warning signs, and help you decide whether a repair or full replacement is needed.
This site receives compensation from the companies featured in this listing, which may impact where and how products appear. This listing doesn’t feature all companies, products, or offers that may be available.
This site receives compensation from the companies featured in this listing, which may impact where and how products appear. This listing doesn’t feature all companies, products, or offers that may be available.
What Are the Signs of a Sagging Floor?
Spotting a sagging floor isn’t always as easy as it sounds. Slight sags can be hard to see, but there are a few telltale signs you shouldn’t ignore:
- Sloped or Tilting Floors: If your floors visibly slope or tilt to one side, especially when viewed from a distance, this often signals foundation issues. Contact a structural engineer for an inspection.
- Gaps Between Floors and Walls: If you notice gaps between your baseboards and the floor, this can indicate that the floor is pulling away due to sagging. This is usually a sign of weakened joists or foundation settlement.
- Bouncy or Squeaky Floors: Floors that feel springy, bouncy, or squeak when you walk on them may be losing support. This often points to weakened or rotting joists.
- Hard-to-Open Doors or Windows: If doors or windows are suddenly sticking, sagging floors may be shifting the frame alignment. While this can sometimes be seasonal, it’s worth checking for other signs of sagging.
What Are the Possible Causes of Floor Sag?
Sagging floors can happen in any home, whether it’s a century-old house or brand-new construction. 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
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?
Building codes allow for only minimal floor sag — typically around 1/360 of the floor’s width. This amount is so small that most homeowners won’t notice it, and it’s impossible to measure without specialized equipment. However, if your floor is sagging enough to be visible or if you feel a bounce when walking across the room, it’s already beyond acceptable limits.
In these cases, it’s best to contact a structural engineer or foundation specialist immediately to assess the damage and recommend repairs. Ignoring visible sag can lead to more severe structural issues and significantly higher repair costs.
How Do You Fix Sagging Floors?
The right fix for sagging floors depends on what’s causing the problem. If the sag is due to foundation issues, the solution may involve underpinning, installing hydraulic piers, or even mudjacking. These repairs can range from a few thousand dollars to $30,000 or more for severe cases.
When rotting or damaged floor joists are the culprit — whether due to moisture, termites, or aging —the damaged sections usually need to be replaced. This process often involves using hydraulic jacks to lift the floor temporarily while the damaged joists are swapped out. If the damage isn’t too severe, a more affordable and effective solution is sistering, where a new beam is attached alongside the existing joist to reinforce it. Sistering is a straightforward repair that can restore stability and often lasts as long as a full joist replacement.
Since sagging floors can have multiple causes, it’s best to have a professional assess the situation to recommend the most appropriate and cost-effective solution.
Should You Hire a Professional for Sagging Floor Repair?
Yes — sagging floors are almost always a sign of serious structural issues that require professional attention. While it might be tempting to save money by attempting a DIY fix, these repairs often involve heavy lifting, precision leveling, and specialized equipment like hydraulic jacks and excavators. Without the right tools and expertise, DIY attempts can worsen the problem or create safety hazards.
A structural engineer can diagnose the root cause of the sag and recommend the best course of action. Once the underlying issue is identified, a qualified repair contractor can ensure the work is done correctly and safely, preventing further damage and protecting your home’s stability.
How Long Does it Take to Repair Sagging Floors?
The time it takes to fix sagging floors depends on the severity of the problem and the type of repair needed. Minor fixes, such as reinforcing joists or adding support beams, can usually be completed in one to two days. However, more extensive repairs — like addressing foundation issues or underpinning slab foundations — can take several days to a week.
Homes with crawlspaces or basements typically allow for quicker repairs since the area beneath the floors is more accessible. In contrast, slab foundations often require excavation or underpinning, which adds time to the process. Regardless of the repair method, a professional inspection will provide a more accurate timeline based on the specific condition of your home.
Other Considerations?
Fixing sagging floors without addressing the root cause is a temporary solution. If foundation damage is the culprit, you’ll need to stabilize the foundation first. For termite damage, hiring a pest control company to install bait stations is essential to prevent further destruction. Similarly, if water damage is causing the problem, waterproofing the foundation can help avoid future issues.
Permits may also be required for certain repairs, especially for foundation work. While minor fixes like sistering a floor joist usually don’t require permits, large-scale repairs typically do. Permits add little to the overall cost but can delay the project slightly while waiting for approval and inspections.
Addressing these underlying issues before repairing the floor ensures a long-lasting solution and protects your home’s structural integrity.
