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moldy crawl space floor joist

How Wood Rot Causes Failing Floor Joists

If your floors feel like they are bouncy, uneven, and sagging, you could have a problem with the floor joists and support system underneath your house. Wooden supports can easily rot and fail in problematic crawl spaces with open vents, high humidity, and standing water. Learn how to fix these issues and shore up your crawl space supports.

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Have you been noticing that your floors seem to have a bounce to them? Are you suddenly dealing with unexpected humidity in your home? Can you smell a musty odor that wasn’t there before? These are all potential signs of wood rot in your home.

Crawl Space & Wood Rot Solutions in Virginia, Maryland, DC

Wood rot is an important problem you should try to tackle as soon as it comes up. If you have rotten floorboards or rotten joists, the problem will continue to worsen until you decide to fix it.

Are you asking how to repair wood rot in walls, crawl spaces, and foundations? The answer is to rely on an expert from JES to give you a thorough fix to your wood rotting problems.

Does This Wood Rot Look Familiar?

These pictures showcase a variety of cases of wood rot and associated problems. That includes crawl space moisture and mold, both of which can have a severe impact on your home’s structural integrity. The best way to avoid these prominent rotted floor joist problems is to contact a JES expert as soon as you notice them.

All About Wood Rot

Especially if you can’t see the rotting sections in your crawl space or foundation, it’s common to have a lot of questions regarding a rotted floor joist. How to fix a rotted wood floor? How to replace a rotten floor joist in a crawl space? Here are the answers.

Before you can learn how to repair wood rot in walls, you should understand how to discover wood rot in the first place. This is especially important if you don’t frequently visit your crawl space because you need to know when to contact a JES expert for more information.

If you’re trying to discover wood rot in your home, keep an eye out for these potential signs you’ll see around your home.

Bouncy Floors

This is possibly one of the most telltale signs of wood rot. When you move to certain areas of the house, does it feel like it bounces down, then bounces back up? This “bounciness” comes from the way the wood rot eats away at the inside of your floor joists.

If your floor ever feels like it’s not fully stable, you need to schedule a crawl space inspection with JES. The stability of your foundation is supposed to maintain your home for many years, and having a “bouncy” floor can be a very serious sign that something’s wrong.

Musty Odors

Homes have a variety of odors, some good and some bad. Not every odor means something is wrong, but a somewhat “musty” smell isn’t a good sign. That’s because it often comes from the fungus that causes wood rot or from mold growing under or inside your home.

Any time you smell a strange odor in your home, you should try to discern the causes of the odor. If you find that it’s just some burned food, it’s all well and good. However, if you can’t find the cause, you may want to contact JES to describe the smell and see whether it might be related to wood rot.

Unusual Humidity

Wood rot fungus grows because of the overwhelming humidity in a crawl space that isn’t encapsulated. Because of the way air moves through your home, that humidity can easily move up into the rest of your house, causing unnecessary humidity in your home as a whole.

Any time you’re starting to experience humidity that’s strange for the time of year or for the humidity levels outside, there’s probably a problem. Whether it’s standing water in your crawl space, a leak in your walls, or something else, that humidity can become a larger problem, and you need to get a JES expert to help.

Wood rot can almost always be attributed to some sort of overwhelming moisture in your crawl space. If you’re experiencing too much moisture in your crawl space, you can run into problems that stretch far past just wood rot.

What else can moisture do to your crawl space? These problems can easily arise with unchecked crawl space moisture.

Mold and Mildew

This is one of the most prominent issues associated with a moist crawl space. If your crawl space has too much moisture, it’s easy for mold and mildew to start growing all across your crawl space.

Mold and mildew have wide-reaching consequences. You could experience health problems and structural damage. Plus, these problems don’t just stay contained to your crawl space; they rise up to the rest of your house as well.

Because it’s so easy for mold and mildew to grow in moist crawl spaces, it’s important for you to handle crawl space moisture early. A JES foundation repair expert can not only determine whether or not you have mold but also help you deal with it.

Insects and Rodents 

Once your crawl space starts having issues with mold, the next step is almost always insects. When insects move in to feed on the mildew and mold, rodents will then start to infest the area to feed on the insects.

These insects and rodents can cause their own health problems, and it can be very upsetting to handle a pest infection. However, you can usually avoid it if you start with the problem early.

Your best bet when it comes to avoiding insect and rodent infestations is to start handling the problem early. As soon as you start to suspect you have high humidity in your crawl space, contact a JES expert for a free inspection.

A Lack of Insulation

Moisture in your crawl space very quickly starts seeping into the crawl space insulation, which is supposed to help your home stay warm in the winter and cool in the summer. However, the moisture takes much of that away.

Wet crawl space insulation is difficult to clean up and replace, and it’s a great place for mold and mildew to grow. Plus, moisture reduces your insulation’s R-value, which means it’ll start working less effectively to insulate the space.

If you already have wet crawl space insulation, the only option is to replace it. A JES expert will be able to clean up and replace your wet crawl space insulation professionally.

If wood rot repair in a crawl space isn’t a homeowner’s game, then how can you fix it? A professional knows many ways to tackle wood rot. The way a specific professional will fix it varies depending on the reasons for the wood rot and the specific circumstances.

Although this isn’t a complete list of methods, it’s a good starting point. A JES expert will be able to go over potential options for your home specifically.

Crawl Space Encapsulation

This is the ideal fix for a home with a dirt crawl space floor. Dirt will always release moisture into the air. Even if you dry out the top layer as much as you can, moist soil is always only a few inches down into the floor.

Crawl space encapsulation blocks off all entrances for water, including any open vents and the dirt floor. With proper encapsulation, you won’t have crawl space moisture problems caused by warm air entering a cold-air crawl space.

If you have a dirt crawl space floor, you’re probably going to need crawl space encapsulation before you can focus on wood rot repair in the crawl space. A JES expert can help you plan it out.

Sistering Floor Joists

Although sistering a floor joist isn’t the only method of fixing wood rot, it can be an important part of it. A professional fix may include sistering certain floor joists that need more support.

This is especially important if the wood rot is just building off poor support structures in the first place. These joists would have to be strengthened anyway to maintain your home structure.

Your floor may need sistering as part of the wood rot fix, even though it’s not the end of the fix. A JES expert will let you know whether sistering should be part of the fix you’re investing in.

Replacing the Rotting Wood Floor 

In extreme circumstances, the wood rot in your floor space may extend to an entire floor, causing rotten floorboards. If your wood rot has extended to floor rot, an expert may need to replace the whole floor.

Although this can certainly be annoying, it’s an important part of making sure your home stays safe. After all, you need to get rid of all the wood rot in your crawl space if you’re going to make sure it stays away.

A JES expert can help you walk through the rotting wood floor issues you’re having. From there, you can develop a customized solution.

Get Help With Your Floor Rot From the Experts At JES

Floor rot is a difficult problem, but it’s not an impossible one to tackle. If you’re wondering whether or not you have rotten joists and wood rot in your crawl space, contact a JES expert for a free inspection.

The only way to tackle your floor rot problems is to understand what’s going on in your crawl space. Get your information from an expert and start fixing your home issues today.

Frequently Asked Questions About Wood Rot

Wood rot can strike fear into homeowners’ hearts. What should you know about wood rot and your potential options for getting rid of it?

The wooden supports beneath your home tend to serve you well as both structural necessities and home insulators. However, under specific conditions, these supports can begin to bow and succumb to wood rot. 


A combination of warmth and moisture can lead to the first signs of wood rot throughout your home. While it is these conditions that trigger wood rot, they are not the condition’s sole cause. That honor goes to fungus. 


Fungus, like mold, flourishes in places where it is allowed ready access to warmth and moisture. Fungus spores can make their way into your home through the air currents that enter your vents. Should they have the opportunity to settle, then they can stick in your wooden supports and begin to develop communities. These communities—otherwise known as the rot—will continue to flourish unless you take steps to limit the amount of moisture or warmth they have access to. 

Exposure to Water 

Residents in colder parts of the country do benefit from their locations, as starker winters can stave off wood rot. However, if you live in the south or the west, you may find yourself contending both with unwanted levels of moisture as well as temperatures that facility condensation and humidity within your home. 

Droughts can also bring water and wood rot into your home. How? Droughts cause the soil particles around your foundation to shrink. When the weather finally breaks, water will rush straight past your soil and into your home. It can, in turn, more readily start to rot away your joists and other structural supports. 

Repairing Water and Wood Damage 

In either case, you have the opportunity to work with a crawl space repair professional in your area to stave off wood rot. You can conduct a home inspection to determine whether or not you have a leak on your hands. Should damage have appeared in your home, you can invest in repairs and then in the waterproofing measures that will prevent fungal communities from reappearing. Some of the most effective waterproofing measures include: 

  • Interior drainage systems 
  • Sump pumps 
  • Full encapsulation with a vapor barrier 
  • Dehumidifiers 
  • Waterproof insulation  

Note that you can tailor your use of waterproofing measures based on where a professional believes the bulk of the damage to be in your home. Additionally, make sure you attend to the specific problem plaguing your home before installing a waterproofing solution, as failing to do so can see all of your hard work undone—a heavy rain, after all, might be able to navigate around a waterproofing measure if the source of your home’s leak hasn’t been attended to.

When it comes to fixing a bouncy floor, you’re doing more than just making your home safe to live in again. You’re also taking steps to ensure that any leak in your home has been patched, and that said leak is unlikely to break open after the next heavy rain. 

Effectively, it is in your best interest to reach out to a professional contractor for a home inspection. This way, you can determine where the moisture in your home is coming from and what solutions you might have to take advantage of to patch up either a crack or a leak. 

Your Available Solutions 

Only once that leak has been attended to should you try to fix your bouncy floors. Your options, at this stage, are ample, and you can again work with a professional to determine which of those available to you may best suit your needs. 

The best ways to fix a bouncy, wood-rotted floor include: 

  • Installing bridging. When your floor starts to sag, they benefit from additional supports. One of the easiest ways to provide your floor with that kind of support is to install new bridging, or an X-bracing. X-braces take the weight of your floor off the joists in your home that may have suffered from wood rot. While your floor won’t return to its original stiffness with these braces in place, you can make your home safer to traverse. 
  • Layering new plywood. If you’re looking for a more comprehensive solution, you can opt to install a new plywood layer underneath a sagging floor. This task can be arduous if you try and take it on without assistance. By installing a new plywood base, however, you can restore the stiffness your floor had before it suffered from rot, though the boards themselves may still squeak. 
  • Installing a new support beam. If you want to give your joists a little extra kick, you can opt to install an additional support beam or wall underneath a sagging floor. Again, doing so will not return your floor to its original state of stiffness. However, by providing your floor with another support, you can take the weight of it off of suffering joists. 
  • Install a specialized stabilizer. To shore up sagging floors and help return them to level, you can have professionals install support jacks. Typical light-duty support jacks can easily fail, however, so it is best to have the IntelliJack™ installed to properly and permanently reinforce your floors. This system is much more reliable and stronger than conventional jacks. 

Note that while you can take on some of these projects on your own, it is often in your best interest to let a professional take on the work for you. This way, you don’t have to invest in new tools or the equipment you might otherwise need for a successful installation.

Replacing a rotted floor joist in your crawl space requires a significant amount of work. Not only will you need to stabilize your sagging floor, but you’ll also need to ensure the leak in your home that caused your floor joist to rot has long been attended to. Only once these initial steps are out of the way should you try and go about replacing a rotted floor joist. 

Even then, it is often in your best interest to reach out to a professional instead of trying to take on a replacement job on your own. A professional contractor in your area can help you better understand what the replacement process might involve and how best you can go about it while also securing the value of your home. 

Replacing Rotted Floor Joists on Your Own 

Attempting to replace a joist on your own, comparatively, can backfire in a few different ways. To begin with, it’s easy to make a mistake while replacing a rotted floor joist. Joists are tricky to work with, especially if you don’t have the tools on hand you need to conduct a safe replacement. If you do install a new joist incorrectly, you risk further damaging your floor. 

As such, you put your family at risk while also reducing the overall value of your home. Should you have to reach out to a professional later down the line for assistance, then you’ll find yourself potentially paying more for applicable services than you would have had you reached out to a contractor in the first place, as the contractor will have to remove the joist you installed before implementing a solution of their own. 

Working with Professionals 

The process through which a professional replaces a rotted joist in your crawl space or basement will require a team to: 

  • Shore up your rotting floor. Professionals can opt to install a supportive plywood layer beneath the sagging floor of your home for support. Alternatively, they can install several two-by-fours to serve as temporary support beams throughout the repair process. These supports are necessary, as they’ll stand in for your support joists while they’re being replaced. 
  • Remove and replace the joist. Whether a professional is replacing one joist or multiple, they must first separate the joist from your home’s subfloor. From there, they can cut away any additional materials that secured the joist in place and swap a sturdier joist out for the older unit. 

Note that if your joists are not visible in your basement or crawl space, a contractor must first remove any insulation, cement, or barriers keeping them out of sight.

Replacing a rotted floor joist in your basement requires much the same time and attention as replacing a rotted floor joist in your crawl space. Doing so can help you better stabilize the floors in the rest of your home, but the task is still dangerous to undertake without professional guidance. 

With that in mind, you have two options available to you. You can either attempt to implement a DIY floor joist solution, or you can contact representatives with your local professional contractors and invest in third-party repairs. 

DIY Floor Joist Replacement 

If you want to try and remove rotted floor joists in your basement on your own, you’ll need to make sure you have a secure step ladder and the appropriate tools on hand to do so. Note that you might not only put yourself in danger by undertaking this task, but you also risk permanently damaging your floors and lowering the overall value of your home. 

If you make a mistake while replacing your basement’s floor joists, you may find yourself contending with bowing floors until you’re able to reach out to a professional. If the damage done is especially significant, then you may never have the opportunity to sell your home for its original value. Instead, you will have to compromise, thereby losing money where you originally intended to save it. 

Contacting the Professionals in Your Area 

Alternatively, as mentioned, you can reach out to the professional contractors in your area for help protecting your home from damage. A contracting team can walk through your basement with you and determine first where the rotted floor joists are, then how best to remove and replace them without putting the rest of your home at risk. 

The process requires the following steps: 

  • Shoring up your rotting floor. As with replacing floor joists in your crawl space, professionals will need to determine early on how best to shore up your floor. They can do so with help from a supportive plywood layer or the support or a two-by-four grid. These supports will hold up your floor while a professional replaces your rotted joints, but that does not mean that your floors will be safe to walk on until the repair process is complete. 
  • Removing and replacing the joist. To start removing joists, a professional must pry the rotted joists away from your subfloor. With those pieces out of the way, they can place a sturdier joist and secure it with carpenter’s glue, screws, or materials of their choosing.


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