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Sagging Floors

Sagging floors can be a massive risk to the structural integrity of your home. Look out for these problem signs so you can catch the issue early and get the right fix.

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When your floor is beginning to sag, you know you’ve got a big problem on your hands. Sagging floors can be extremely damaging to your house’s structure, and they can be indicative of a much larger issue. This issue is usually caused by the wooden support beams or floor joists in your crawl space rotting away due to fungal growth. This is a massive issue that needs to be rectified as soon as possible. 

However, when floors are beginning to sag, it isn’t always obvious. By the time you notice, the floor could be so far gone, you’ll have to spend costly amounts of money to not only replace your floor but the wood in your crawl space as well. So how can you spot the problem signs that indicate sagging floors? Here’s everything you need to know: 

How to Spot Sagging Floors 

Once the wooden supports in your crawl space start failing, the entire house will be affected. This is why you can still know when your floor has started to sink even if the sagging isn’t significant. If your house’s structure is displaying the following problem signs, check the evenness of your floor. 

  • Moving Objects 

When the floor is uneven, anything that can roll will do so without much effort. Balls, pens, and other objects won’t stay where you place them. The more significant the sagging, the more the objects will roll. If you believe your floor is sinking, but don’t have a level ruler to test it out, you can always place a small ball on different parts of the house to determine where the sagging is occurring. 

  • Tilted Furniture 

If you feel like the furniture in your home is tilted, you need to check their legs. If the legs are stable, the problem is probably the sagging floor. No matter how slight it is, you’ll be able to notice the sinking best on chairs, couches, and tables. 

  • Bouncing Floor 

Your floor might not show any signs of sinking, but if it’s soft and bouncy, it will sink soon. Sagging floors occur when the wooden beams under the crawl space are unable to hold up the weight of the house. Depending on the type of fungus that debilitates the beams, the wood becomes soft and bendable. If the wood rotting occurs in an area of the house that isn’t walked on often or doesn’t have to hold up a lot of weight, the floor will be bouncy but won’t sink until pressure is applied to it. 

  • Ceiling Cracks 

The wooden supports in the crawl space don’t just hold up the floor. They serve as a foundation for the entire house. However, wood rot and floor sagging do not happen evenly. Because of this, a certain amount of pressure is applied to the rest of the wood. That pressure travels along the walls of the house and affects the roof. As a result, the ceiling cracks and might even begin to fall off if the wood rotting is severe. 

  • Jammed Doors 

When the floor of a house begins to sag, the most common problem you could experience is a jammed door. The door will have trouble opening and closing if the floor is sinking. Wood rot doesn’t just cause one part of the floor to sag, it also lifts other parts of the floor because of the uneven distribution of pressure. This lifted part interferes with the door, causing it to jam. 

  • Cracked Walls and Columns 

Due to the uneven distribution of pressure from the sagging floor, walls and columns are bound to crack. Many homeowners see cracks on their walls and don’t think much of it, believing that it can simply be patched up. However, because the crack is caused by the force the sagging floor is exerting, this is something that can only be fixed if the crawl space is repaired, and the house is given proper support.  

  • Broken Door Frames 

Another obvious sign of floor sinking is broken door frames. Just like wall and column cracking, door frames will break apart under the upward force exerted by the unstable wood in a crawl space. Your door can become unhinged from the damage and might refuse to open or close properly. 

What Causes Sagging Floors? 

There are multiple reasons as to why the floor of a house would sag. In a state like North Carolina, the most common reasons as to why a floor would sag have to do with there being too much moisture in the crawl space. 

An uncovered crawl space is subjected to flooding, leaking, and high amounts of humidity. This has a profound effect on the crawl space’s concrete, wood, and the soil beneath the wood. 

  • Concrete  

Concrete is affected the most by water during the winter. When water freezes, it expands by about 9%. Although a bit of water seems like no match against tough concrete, it can actually cause the concrete to break apart. When the water freezes and expands, if it goes past the concrete’s tensile limit, it breaks apart the concrete’s surface. When concrete erodes in this manner, it is more likely to crack and break. 

When not subjected to the freeze-thaw effect, moisture still affects concrete but not so severely. At most, the concrete will get discolored because moisture can sometimes bring certain salts to the surface of the concrete. If all you see is discoloration in your concrete you won’t have to worry. 

What holds up your house isn’t just wooden beams. The concrete walls and supports also serve as a foundation. When these begin to crack and break off, the wood is also affected. Floor sagging can occur even if the wood itself is healthy. However, it is very rare for the cause of floor sagging to only be one thing. If there is moisture in your crawl space and your concrete is being affected, there’s a high probability that the wood is being affected too. 

  • Wood  

Fungus grows in hot, humid places. However, fungi are living organisms who need to consume some sort of food in order to survive. So, when the humidity and temperature are just right, fungus grows on wood and consumes it. This is how wood begins to deteriorate to the point where it can no longer support your home. It depends on the type of fungus that grows on your wood, but some of them even cause shrinkage in the wood. 

Fungus isn’t the only thing eating away at your wood: Termites and carpenter ants also make a nest out of your crawl space and eat the available wood. This is a big problem in crawl spaces that aren’t encapsulated. Fumigating every couple of months isn’t necessary when the entire crawl space is closed off with thick, air-tight sheets, so encapsulation is something you might want to consider if you haven’t already. 

  • Soil  

Some of the biggest problems homeowners in Raleigh and Winston-Salem, NC, experience are caused by soil. The vast majority of North Carolina’s soil is a reddish clay soil called Cecil soil. The problem with this type of soil is that it absorbs a lot of moisture. The more moisture soil can absorb, the more it shrinks once all that soil dries up. 

When soil loses moisture and shrinks, it loses its surface volume. When this happens, whatever the soil was supporting will crack and settle on to the soil eventually. In crawl spaces, this can happen to the concrete and wood that’s meant to support the house. If concrete settles because of shrinking soil, it’s very likely that the floor will sink to reflect this change. 

Sagging Floors


There are different kinds of fungi that can grow on your wood and cause floor sagging. Identifying how exactly your wood is rotting will help you determine when to take action and repair the crawl space and understand what can be done to prevent further damage before things get severe. Depending on the fungi, the wood can rot in two different ways: dry rot and soft rot. 

Wood rot can still be salvageable depending on how it’s rotting. Of course, getting rid of the fungus is a lot harder than you’d think, but it’s still worth at least knowing how your wood is being affected. Take a flashlight and a screwdriver with you down to your crawl space to do a quick inspection and you’ll be able to tell what kind of rot you’re dealing with. 

  • Dry Rot  

Dry rot is any kind of fungus that eats away at wood without softening it. The most common type of fungus that does this to wood is known as brown rot. Brown rot was originally just called dry rot because it was believed that it didn’t need moisture to survive, but this isn’t true. People soon discovered that brown rot is capable of pulling moisture from afar, which is how it can survive even when the humidity levels are relatively low. 

Brown rot specifically can be identified because it leaves a pattern on the wood that looks like small squares. It is often confused for termites, so another way to determine if the damage was caused by brown rot is to check for red spores. 

  • Soft Rot  

Soft rot affects wood differently from dry rot. This kind of fungus makes the wood feel soft and spongy. It often discolors the wood and turns it either green or white, though white is the most common. These kinds of fungi tend to shrink the wood as well. 

While wood suffering from dry rot can be saved, the ones that go soft from rot are unsavable. Once the wood becomes soft, it is too deformed to function as a support beam. Even if it’s cured of rot, the wood is too shrunken down and is unable to support the same amount of weight it was once able to. When dealing with soft rot in wood, you might have to replace it depending on the extent of the damage. 

One of the best things you can do for your home’s structural integrity is protecting the materials in your crawl space. This will extend the life of those materials and also minimize the number of repairs you have to do around the house. Whether you want to prevent sagging floors or you just got them repaired and want to keep them stable for as long as possible, here’s what you have to do to protect your crawl space and floor. 

  • Waterproofing  

To truly protect your crawl space, you need to fully waterproof it. This means full encapsulation and the installment of an interior drainage system, a sump pump, and a dehumidifier. The encapsulation will protect your crawl space from flooding and will make it more difficult for insects to get inside that could potentially ruin your wood. Encapsulation also makes your crawl space easier to clean and access, so if there’s anything in the pipes or flooring you need to check out, you won’t have to worry about getting dirty. 

The interior drainage system sump pump work together to intercept any water that enters the crawl space and drain it elsewhere. The dehumidifier keeps the humidity levels low in the crawl space. These modifications are sure to protect your crawl space, which protects your floor. 

  • Small Changes  

While you should seriously consider fully waterproofing your crawl space, there are other things you can do to prevent moisture from destroying your wood. These small changes are no substitute for full waterproofing solutions, but it’s a start. If your crawl space has vents, you can install vent covers to make sure water doesn’t have such an easy time flooding the place. You can also extend and alter your downspouts so that they point away from the crawl space and dump the water as far away as possible. A good five feet is far enough away; any closer and the soil will soak up the moisture. 

You can also spray a wood preservative on your wood. They protect the wood from anything that can cause deterioration. When using wood preservatives, it’s important to only use it once a year and only use it in moderation. They contain insecticides and other harmful chemicals. Most of the air we breathe in our homes comes from the crawl space and the warm air will rise and bring with it the wood preservative, so treat it as you would any other insecticide and stay out of the house for a few hours after spraying. 

Having to replace the support beams just because your floor is sagging can be a real problem. Before you start thinking about that, you’ll need to get in contact with a foundation and crawl space expert who can inspect the damage and find the best course of action. 

  • If Replacement is Necessary  

Once the inspection is done, the contractor will let you know how to proceed. There’s a chance that a full replacement of the wood in your crawl space is unnecessary and only certain parts need to be reinforced. Remember, the wooden structures in your crawl space that support your home isn’t just limited to the beams. 

The sill plate, band joist, the insulation, and the concrete walls are all part of a symbiotic structure that works together to support your home. If the contractor inspects the crawl space and talks about replacing things, don’t worry: It doesn’t automatically mean the whole crawl space needs to be completely remodeled.  

  • If Replacements Aren’t Necessary 

If nothing in the crawl space needs to be replaced, the most common way to fix sagging floors is by using joist stabilizers. They are specialized jacks that hold up beams and evens the flooring in your home. Steel beams can also be added for extra support. Nailing together a sister joist is another common way to strengthen the joists. This is especially good for wood that has been cured of dry rot and just needs a little extra help supporting the flooring. 

The contractor might suggest at least installing a sump pump if full encapsulation isn’t something you’re able to do at the moment. After going through the trouble of adding new support for your sagging floor, taking care of it would be wise. 

Can I Fix Sagging Floors Myself? 

If you have sagging floors, you might think that the solution to the problem is simple: Just jack up wooden beams in the crawl space and find a sturdy support to even out the floor. However, repairing sagging floors isn’t something you should try to do yourself. The entire structure of your house depends on the integrity of the foundation. If you don’t do a good job, you could end up having to repair more than just your crawl space beams. 

Yes, sagging floors can be evened out again by installing specialized joist stabilizers that can hold up the bending support beams. However, this isn’t something that can be done without planning and without understanding the root cause of the sinking floor. Without understanding the why, you can never truly repair the issue. 

  • Why DIYs Can’t Fix Sagging Floors  

As mentioned previously, sagging floors can be caused by multiple problems in a crawl space. It’s not enough to simply install a joist stabilizer to hold the weak wood up. As long as the crawl space is humid and unprotected from flooding, the conditions of the wood and concrete in your crawl space will continue to do untold damage to the structure of your house. 

Even something as simple as getting rid of fungus is complicated when it comes to crawl spaces. In order to fully get rid of it, you would need to dry out the wood and bring down the humidity levels of the crawl space as low as possible. This cannot be done with a normal dehumidifier because they aren’t potent enough to bring down the tremendous amount of humidity a crawl space has. 

You would also need to spray fungicide on the wood. The kind of fungicide products sold at the store usually aren’t strong enough to thoroughly rid the wood of the growth. Only professional-grade fungicide can, so even if you wanted to fix the issue yourself, it’s unlikely you would have the right tools at your disposal.  

  • How DIYs Can Potentially Make the Problem Worse 

The biggest problem with DIY resources is that they don’t go into specifics about what you’re trying to fix. They try to make things as simple as possible so the average homeowner is able to understand what they have to do. However, this can lead to a lot of problems. 

There are so many moving parts when it comes to sagging floors that if you try to repair it yourself, you could end up making things worse. For example, if you try to install new support to hold up the floor, you could potentially place a lot of pressure on the soil. This causes soil compaction, which is when the air in the soil gets displaced by placing a heavy weight on it. This can lead to settling. 

This and so many other things need to be considered before any repairs can be done. This is why it’s important you contact an expert to help you fix and even out sinking floors. 

Call Tar Heel Basement Systems for Crawl Space Repairs 

Repairing sagging floors can be a bit complicated. There can often be more than one element that contributes to the problem. Floor specialists don’t generally deal with sagging floors caused by crawl space deterioration, so you need to get in contact with foundation and crawl space specialists who know how to properly handle crawl space repairs. 

Here at Tar Heel Basement Systems, we have certified experts that are able to determine the best course of action for your problem. We are happy to serve the homeowners of Raleigh and Winston-Salem, NC, and have been doing so since 2003. We specialize in foundation care and repair, so our experts can give you a simple, hassle-free, cost-effective solution for sagging floors. 

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