Updated at: 17-10-2022 - By: cnbusinessnews

The pain of needless and expensive repairs can be avoided if you know how to detect if a water damaged subfloor is okay. Subfloor damage can be detected by looking for telltale signals that the subfloor needs to be replaced.

Subfloors, whether concrete or wood, are particularly vulnerable to flooding. To mend it quickly and easily, it’s important to notice the early signs of wear so that it doesn’t get worse and spread. Continue reading to find out if your subfloors are in good condition and what else you need to know about assessing the damage on your own.

A subfloor is a layer of material that is installed beneath the visible floor surface. Wood, OSB, plywood, and other materials are commonly used. For example, tile, hardwood, or laminate can all be laid on top of this foundation.

Wood strands and glue are combined to create OSB, a material that is commonly used in construction. Due to the simplicity of installation and reduced cost compared to plywood, this is a common subflooring material. It is also less expensive than other conventional subflooring materials like plywood. As a result, OSB subfloors are common in contemporary construction.

The definition of what constitutes a subfloor varies from location to location in a home. Concrete flooring can be considered the subfloor surface in various areas of the house, such as the basement. The concrete surface is often left uncoated. In spite of this, it’s still regarded a subfloor.

Concrete may be used as the subfloor in some buildings, with a covering of another material placed on top. You will, however, need to lay sleepers before installing your preferred floor material.

An ideal subfloor should survive as long as the house it’s attached to. Because of this, subfloor repairs aren’t a regular occurrence. In some circumstances, the subfloor may need to be replaced if it begins to exhibit indications of wear and tear.

Subflooring issues are most common 20 to 30 years after the surface is installed. If the installation is of poor quality, the problems may come up sooner. As a result, you should be able to detect when the surface should be replaced.

The first step in subfloor replacement is to remove the entire top floor. As a result, you must be certain that there is a problem with the subfloor. If you misinterpret the circumstance, you will suffer additional fees.

A lack of knowledge about how to do the replacement could result in a shoddy job, as well If you wait too long to replace the subfloor, you may have to do so again in the future.

Before you replace the subfloor, here are some things you should know. To begin, there are telltale signals that it’s time to replace your subfloor.

Signs That Your Home’s Subfloor is Damaged

When the subflooring material is deteriorated and dangerous to walk on, it is usually replaced. It is possible, however, that subfloor unevenness is a sign of a more serious structural issue in the foundation or floor joists. It’s possible to experience multiple of these circumstances at the same time.

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1. Loud Squeaks

The squeaking of floorboards is a typical occurrence, even if it is barely audible. If you hear a squeaking sound coming from your floor, it’s most likely caused by wood rubbing against a nail. Skims or wood screws can be used to repair a squeak if you can pinpoint its source.

The squeaks are caused by the subfloor’s loose materials. Alternatively, the OSB or any other subfloor component may be loosely linked. If you’re going to have subfloor noise, you’ll need to nail it into place. Subfloors that have begun to warp are likely to produce creaking noises.

Unlike plywood, OSB is more prone to buckling and warping. Squeaks will be heard as you walk on it as a result of the nails loosening from the joists.

Squeaky floors don’t always necessitate a new subfloor.

2. Weak Subfloor

There should be no dips or weak spots in the subfloor. When you walk on your flooring, you may discover that it is spongy, or that there is a noticeable weakness in the subfloor. Here are some possible causes of a subfloor that is weak or uneven:

  1. A water leak or moist crawl space has caused water damage to the subfloor.
  2. More than 16 inches apart, the floor joists or trusses are in place.
  3. The subfloor’s border does not rest on a joist.
  4. The subfloor will be uneven if the floor joists or trusses are unequal, which indicates a structural concern.

As moisture seeps into the flooring, it weakens the surface, which can be caused by plumbing leaks or a wet crawl space. Your subfloor and floor joists might dry rot without your knowledge if you have a crawl space moisture problem.

The crawl space may need to be encapsulated or a water drainage system like a French drain installed if you have a long-term moisture problem.

Floor joist lengths wider than 16 inches on center (o.c.) were tested by builders in the 1980s and 1990s to discover how far they could go without sacrificing structural integrity. Floor joists that span 24 inches o.c. or more are still common in many homes today.

The subfloor will bend underneath if the floor joists span more than 16 inches o.c. unless diagonal 1-inch thick planks are used. In order to prevent deflection, floor joists should be at least 16 inches on center (o.c.) for plywood and OSB.

It’s possible, though, that the subfloor was improperly installed. The subflooring’s ends must meet in the middle of the floor joists during installation. There will be no way for the plywood or OSB to capture part of the floor-joist, which will cause the edge to float and feel weak. Dimensional timber that is bent or not correctly framed.

3. Cupping Floorboards Due to Moisture

Because a floorboard is supposed to be flat, cupping is a sign of an underlying issue. As a result, the house’s value is reduced because of the warping. A crooked or uneven floor is an eyesore.

Your flooring may be curling in certain places, as you may have seen. It’s not uncommon for them to separate due to dampness under the final flooring. You can’t say for sure that the curling is caused by an issue in the flooring in this situation. Moisture may have been able to get through the floors because they weren’t properly installed.

However, there’s a chance that an underlying problem in the subfloor is causing the weakness of the subfloor.

4. Cracked and Popping Tiles

There is, however, a possibility that an underlying issue in the subfloor is to blame for the subfloor’s deterioration.

Make sure the popped tile doesn’t have any trowel marks. A thin, dry set with no marks is a significant red flag that something is wrong. Moisture is most likely building up in the subfloor.

It’s possible, though, that the tile and subfloor are incompatible. Ideally, the subfloor should be covered with a cement board prior to putting tiles. It aids in the construction of a stable base for the tiles to rest on. As a result, it lowers the bounce that causes tiles to break.

Whatever the cause of the cracking or popping, it doesn’t make a difference. Your subfloor needs to be fixed if you notice it. If you don’t fix the problem, your tiles will keep breaking down.

5. Musty Smell

Smells emanating from the floor indicate that the subfloor has moist wood and maybe mold growth. It’s a sign that water has built up in a particular area. Mold thrives in a moist crawl area like no other.

A musty odor is the first indicator of mildew growth. The damage has already been done by the time you notice the smell. Bathroom subfloors and other places that are frequently exposed to dampness are particularly prone to this problem.

Groundwater or plumbing leaks are the most common causes of musty odors in a crawl area. Both of these conditions, if left uncontrolled, can lead to significant structural and subfloor damage.

A vapor barrier, dehumidifier, or crawl space encapsulation may be necessary in addition to the replacement of wet subflooring when dealing with chronic groundwater concerns.

Plumbing leaks can sometimes be repaired and the subfloor damage can be replaced all in one step.

Additional bracing between floor joists may be used instead of subfloor replacement in modest occurrences of subfloor damage.

The subfloor cannot be replaced from the bottom up. The only way to provide more structural support is to brace it. If the subfloor is damaged, some contractors will put blocks between the floor joists or cut a thin piece of new plywood or OSB to push against it and then brace it for support.

6. Bouncy Floor

If your floor gives you a bouncy sensation as you walk, you should be concerned about the condition of the subfloor. The floorboards may also be shifting as you walk. A issue in the subfloor region is indicated by the fact that it is not common for this to occur.

A spongy surface indicates that the floors and subfloor are not properly connected. The most likely scenario is that the subfloor is shaky and can’t handle the weight from above. As a result, the best way to remedy bouncy floors is to inspect the subfloor and fix any issues that may be present.

There are two possible causes of a bouncy floor:

  • Dry rot in the floor structure of the crawl space is the outcome of a moisture problem.
  • foundation support has been deemed ineffective

7. A Loose Toilet

Ideally, a toilet should rest firmly on the floor. If the subfloor region is weak, the anchors that hold the toilet in place are not strong enough to keep it in place. Moisture damage to the subfloor is the most common cause of toilet problems.

When you see movement in your toilet, fix the problem immediately. As a result, further harm can be avoided. To avoid a repeat of the problem, you will need to fix the subfloor and the leaking pipes.

Moisture damage can also spread to other places of your floor, particularly around your front entrance. Moisture from rain or snow can seep into the subfloor if the door isn’t properly installed.

In regions where flooding is a regular occurrence, subfloor damage is common. In other words, rather than constantly fixing your subfloor, start by making your house waterproof. It will go a long way toward limiting the collection of moisture, which may be extremely damaging.

8. A Leaky Ceiling

Subfloor damage might occur if your ceiling leaks. In the event of a catastrophic roof leak, water falls from the ceiling onto the floorboards. A subfloor that has been exposed for an extended period of time may need to be replaced.

Therefore, replace the subfloor it is damaged from a roof leak. If you respond quickly, the damp subfloor can dry and you won’t have to replace it. Moisture exposure over time causes subfloor wood decay.

What Causes Subfloor Damage

Therefore, replace the subfloor it is damaged from a roof leak. If you respond quickly, the damp subfloor can dry and you won’t have to replace it. Moisture exposure over time causes subfloor wood decay.

As a result, if the subfloor has been damaged by a roof leak, it should be replaced. By acting quickly, you can allow the damp subfloor to dry and avoid having to replace it. Over time, moisture in the subfloor can cause wood rot.

Water is the primary source of most subfloor damage, but there are others. According to the US Department of Housing and Urban Development (HUD), bug infestations are to blame for the damage. A weak subfloor might also be caused by a location that experiences regular earthquakes. It could also be due to a problem with the foundation of your floor.

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It’s important to note that the subfloor is damaged in sections. Because of this, it’s uncommon to locate a subfloor that extends throughout the entire room. As a result, fixing the problem should not be a problem if the cause and the location of the harm are found.

We’ve provided a list of the most prevalent indicators here. To help you determine whether to hire a flooring professional, they should serve as your guide.

How To Know If Your Water Damaged Subfloor Is Okay

Step #1. Listen for a loud squeaking on your floorboards

It’s not unusual for a floor to squeak slightly. It’s not uncommon for folks to ignore the annoying squeak and avoid stepping over the creaky area of the flooring. However, if you hear a distinct squeaking sound, you may have a warped or twisted subfloor.

A squeaking sound is produced by nails moving repeatedly in and out of the subfloor’s wooden joists. The subfloor should be nailed to the joists as a best practice. When there is a risk of water damage, the nails become loose, resulting in the dreaded squeaks.

The damage can be assessed by inspecting the floorboards underneath if you hear a lot of creaking. You can begin arranging the repair process from this point onward.

Step #2. Check for signs of mold

A moldy, polluted subfloor is most likely the source of a peculiar, musty stench coming from your floor. It is possible that water damage from mold will result in a squeaky, uneven, and even soft floor.

In the case of a molding subfloor, it may be difficult to locate the cause of an unpleasant odor. Inhaling mold spores can be hazardous to your health, so be sure to use a mask or other respiratory protection when doing so.

If you want to eliminate the mold from your subfloor, there are a variety of methods you can use. The disadvantage is that you and others around you run the risk of spreading the spores. Instead of trying to remove it yourself, you should contact in the experts.

Step #3. Look for cracks on tiles

Seeing cracks in tiles can indicate that the flooring beneath it is weak and pliable. Tiles need a robust and rigid surface underneath to prevent them from breaking and cracking. If your subfloor isn’t firm enough to hold up the tiles, you can confirm this by scrutinizing your tiled floor for signs of breakage.

Step #4. Look for uneven or sunken sections

Cracks in tiles may indicate that the flooring beneath them has become weak and pliable. To prevent tiles from fracturing and splitting, they must be placed on a solid and sturdy base.. Look for signs of broken tiles on a tiled floor to see whether your subfloor isn’t strong enough to support tiles.

Wood deterioration and heavy foot traffic are to blame for this problem. Despite the possibility of water damage, sinking flooring may also be the result of shoddy subfloor installation. Moisture management is the best approach to keep wood subfloors from deteriorating in the first place.

Step #5. Inspect the finish floor for damage

Look for evidence of wear and tear on the finished flooring to determine if your subfloor is in need of repair. Breakage may appear to be an easy flooring problem, but it could be a sign that your subfloor needs to be replaced.

It is important to address any issues with cracked tiles, warped wood, or peeling Linoleum floor finishes. Perhaps it’s time for a thorough investigation of the subfloor.

It’s possible that water has warped the wood beneath the surface, resulting in a cupping floor. Cracked tiles may indicate that the subfloor isn’t supporting the tiles adequately. Moisture under the Linoleum could be the source of a bubbling Linoleum Floor.

Your insurance company or lawyer should be contacted if you believe that your subfloors have been destroyed to a significant extent. You can find out if your insurance company will cover the cost of repairs if you do this.

Can You Replace the Subfloor Yourself?

If you’re a skilled carpenter, replacing the subfloor should be a breeze. However, it’s preferable to hire an expert because this isn’t just a one-time problem that can be fixed.

The extent of the harm and the cause will be determined by an expert. A seemingly minor problem with the subfloor could turn out to be a major one. You may have some knowledge of subflooring, but it’s best to leave it to the experts, especially if the problem becomes more complex.

Additionally, a professional has the necessary instruments for the job in order to identify the origin and degree of the damage. A flawless task necessitates the use of appropriate equipment and knowledge. Because of this, it’s best to leave it in the hands of a pro who can ensure that all of the issues are identified and addressed.

You’re still in charge of keeping the subfloor safe. As an example, you may pinpoint the cause of water damage to the floor and remedy it, thus preventing further damage. For example, if you notice a problem with the door’s fit, you may be able to fix it without the help of a professional.

As a homeowner, you have a responsibility to check for suspected leaks, according to the EPA. Finding and fixing leaks as soon as they are discovered helps keep the expense of any repairs to a minimum.

As a result, even if you hire a contractor to fix your subfloor, you still need to be involved in its upkeep.

How Much Does It Cost to Replace a Subfloor?

Subfloor replacement costs around $500 for a 300 square foot area, according to Angi. Replacing the subfloor in a larger room might raise the price to $700. The material of choice and the cost of labor are two further factors that can raise the price.

There is a direct correlation between price and quality. When labor expenditures are taken into account, the price might reach $900. On average, one hour’s worth of work will cost $30. Consequently, you must be prepared to pay for the labor expenditures.

What is the Price Per Sq. Ft. of the Property?

Most materials cost between $1.50 and $7 per square foot on average. The pricing reflects the superiority of the product. In terms of cost per square foot, plywood is the lowest option at $1.5 per square foot. As a result, a 300-square-foot room will cost $450.

With escalating construction prices and resource shortages, much of the information available online may be out of date. From 2019 to 2021, material costs have increased by more than treble. OSB runs from $28 to $60 per sheet, whereas plywood ranges from $45 to $75 per sheet, depending on region.

When it comes to replacing a plywood flooring, for example, you may expect to pay between $2.50 and $5 per square foot at today’s pricing.

What is the Cost of a DIY Subfloor Repair?

Are you a fan of DIY projects? If you enjoy making minor repairs around the house, you can take on the task. In spite of this, as previously mentioned, you must be familiar with subfloor mending.

Repairing the subfloor will save you money in the long run. As a result, you’ll simply need to spend money on the supplies. Choose the material you want based on your budget.

You’ll also need to purchase the appropriate tools, even if you already own them. A circular saw, which should cost no less than $40, is required. At the very least, you’ll need a crowbar and nails that cost at least $10. Finally, a nail gun, which costs $150, is a requisite.

Screws rather than nails should be used to replace the 5/8-inch OSB subfloor. When replacing 3/4-inch plywood, use 2-inch screws.

You’ll save money on labor, but you’ll also have to put in some of your own time. The amount of time required will be determined by the severity of the damage to the subfloor. Replacing the subfloor in one room can take up to a day on average.

Though you can save a significant amount of money by doing it yourself, you’re better off hiring a professional. They’ll figure out what kind of subfloor material is best for your home. In addition to fixing things more quickly, an expert will do it for you.

You should expect to pay $30 an hour for a professional. Between $720 and $3,200 is the typical range for the overall cost of labor. Moving goods from the house and removing the old subfloor are two of the things that would raise your labor charges.

In addition, a large room will cost more to furnish than a small one because of the additional labor required.

How Long Does it Take to Replace Subfloor?

If the space is tiny, a professional can repair the subfloor in a matter of minutes. Even if you do it yourself, removing the old subfloor and installing the new one can take up to a week.

It shouldn’t take more than 8 hours for an expert to fix a tiny space. When dealing with a broad area, 24 hours is the maximum amount of time necessary. Because of this, we strongly recommend that you employ a professional to complete the task.

Is it Hard to Install Subfloor?

An easy subfloor installation is possible with the right tools. Therefore, anyone with simple carpentry abilities will be able to swiftly remedy the problem. At first, it may seem like a hassle, but if you take the right measures, everything should go smoothly.

The following are some of the most important things to take when repairing the subfloor:

You’ll Need to Assess the Damage

The easiest way to determine the extent of the problem is to inspect the subfloor. A portion of the finished flooring will have to be removed. Use a flashlight to inspect the degree of the damage after it’s been removed. Crawl space inspections may also be necessary if the subfloor is poor.

To prepare you for the task at hand, the inspection will help you prepare. Ideally, choose the least invasive method of obtaining information. It will be inexpensive and simple to carry out. You may have to remove a substantial portion of the subfloor in order to figure out what’s causing the problem, however.

Make sure the subfloor is in good condition before dealing with a cracked tile problem.

You’ll Need to Determine the Cause

The first step in replacing the subfloor is to figure out what’s wrong. It’s pointless to put in another subfloor if the problem isn’t fixed; it will meet the same destiny as the original.

Check for dripping pipes if you’re working on the subfloor of a toilet. Incorrect installation of your subfloor may also be the cause of warping. The new subfloor area should be corrected for this.

Sometimes, the joists can also break, and it could cause subfloor damage. Fixing the issue will be a piece of cake once you find out what’s causing it.

Repair any Plumbing Leaks

Sometimes, the joists can also break, and it could cause subfloor damage. Fixing the issue will be a piece of cake once you find out what’s causing it.

Sometimes, subfloor damage is caused by joists breaking. Finding the root of the problem is the first step in resolving it.

As a result, check the subfloor to see whether there are any obvious signs of damage. It’s also crucial to know where the water leak is coming from. For example, a water leak could be the cause of the leak. It’s also possible that the subfloor was soaked because of floods in the house.

There’s no need to rebuild the entire subfloor if the water problem was an isolated incident. If you’re in this situation, the following steps will help.

  • Remove all furniture and floor coverings from the afflicted areas to allow fresh air to circulate. In order to speed up the drying process, make sure to mop up any remaining water on the surface.
  • The drywall must also be removed if it has been wet. Allowing the subfloor to dry quickly will be a benefit of this tool.
  • It is also critical to aerate the damaged area in order to hasten the drying process of the subfloor. A box fan is required for this task. To speed up the drying process, place box fans both below and above the floor. Hurricane Box Fan is ideal for this task. It’s a space-saver because it doesn’t take up a lot of room. It also has a top speed of 2400 CFM, which is extremely impressive.
  • A humidifier, on the other hand, can help much with the problem of standing water in the crawl area.

Repairing Dry Subfloor Damage

Subfloor material may still feel spongy even after water damage has been repaired. It is possible to prevent the subfloor layer from having to be removed by strengthening it. It’s also important to make sure that the old layer doesn’t have any mold.

Make sure there are no symptoms of mold or mildew growth before you begin the cleaning process. The next step is to attach a joist material to the underside of the subfloor. It is possible to lay another subfloor on top of the existing one without weakening the structure’s support.

Steps to Installing a New Subfloor

In other circumstances, the leak may have been going on for a long time and the subfloor is beyond repair. It will have to be replaced if that happens. Don’t, however, rush into a total re-do of the flooring. All that is needed is to replace the broken part.

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To replace your subfloor, this is the procedure:

  • To begin, take out the old flooring and dispose of it properly. Whether or not it’s salvageable will be determined by the amount of the damage. Make sure you remove it carefully if you think it’s salvageable.
  • Take out the old, worn-out flooring and replace it with a new one. It is critical that you remove all of the damaged subfloors during this stage. Mold can spread to new parts if you leave a portion of the mold-infested piece behind.
  • Cut the previous subfloor into square symmetrical sections. You won’t have to worry about squeezing into the new subfloor.
  • Consider the thickness of the new subfloor material while making a decision. The joists will be properly aligned with it. Afterwards, apply an adhesive to the sides of the floor where the joists meet. Since most subfloors and floorings are suitable, we recommend Loctite PL Premium glue for this task. A caulking gun can be used to apply a thin, equal layer.
  • Subfloors are laid by screwing them into place. This is the moment to tighten the connection if your floor was squeaking earlier. Nails can also be used, however they are more susceptible to creaking than other materials. As a result, go with screws.

To lay tile, remember that you must first lay the cement board layer. At this point, you should screw it into the subfloor.

Do You Need a Permit to Replace Subfloor

When only a small portion of the subfloor is being replaced, a permit is not necessary. In order to be sure that no other rules or regulations apply, you should consult with your local building department.

Installing a subfloor over the top of a joist or engineered floor structure is standard practice. A permission is required if the subfloor is rotten or damaged so severely that it requires a complete repair.

You may need a permit if you intend to replace a few joists as part of your project, depending on your city’s building codes. After installing new joists or engineered trusses, the building department may request an inspection of your subfloor.

Do Plumbers Replace Subfloor

Only water and waste plumbing is the speciality of plumbers. Subfloors are rarely replaced by plumbers. However, this does not imply that all of them do.

In most cases, you’ll employ a qualified contractor to take care of the structural repairs while a licensed plumber takes care of the plumbing work.

Plumbing repairs are typically carried out in collaboration with a professional contractor hired by the homeowner if the plumber is hired directly.

How to Keep Your Sub Floor in Good Condition

Know Your Subfloor:

The first thing you need to know is that there are a variety of subfloors to choose from, rather than a single one. You need to know what kind of dog you have, because they all require a different level of attention. To find out what materials were used in the construction of yours, you may need the services of an expert.

Removing Rubble and Debris:

The best approach to start degradation under the home and against the flooring is to accumulate rubble and other debris. As a result, you must ensure that any potential dangers are kept out of your workspace. As soon as you notice any signs of decay, you should be on the lookout for rats and other pests, as well as mold, which can lead to serious structural problems in your home.


If you want to keep your flooring in good condition, you must also make sure that it is adequately vented at all times. As a result, the subfloor is kept dry, preventing the growth of mold and flimsy, spongey patches on your floors.


A water-damaged subfloor does not necessarily necessitate a replacement. You can easily dry and fix a wet spot with the necessary tools and know-how if you catch it early enough. If you overlook a wet flooring for an extended period of time, however, you run the risk of rot, mold, and other impurities permanently ruining it.

Knowing how to detect whether your subfloor has been damaged by water will help you decide whether or not to repair it. It is possible to rescue your subfloor from complete replacement by spotting damage early and addressing it before it becomes irreparable.