Rotten Floor Boards

How To Tell if Your Floorboards Are Rotten (13 Signs)

In Home Maintenance by Giovanni ValleLeave a Comment

Floorboards can last for several decades, but if they show signs of wear and tear, they could be rotten. Rotten floorboards can be an eyesore and a health hazard because they may be weak or harbor mold. How can you tell if your floorboards are rotten?

You can tell your floorboards are rotten if they feel soft when you step on them. Warping and cupping can be caused by water damage in your house. They can also be caused by moisture due to high humidity. Mold or mildew can also cause them to rot.

In this article, I’ll discuss ten signs that can help you determine if your floorboards are rotten and need to be replaced. Let’s get started!

1. The Floorboards Feel Soft or Spongy When You Walk on Them

An obvious sign that your floorboards are rotten is if they feel bouncy or soft when you walk over them. This is a telltale sign that they are wet and potentially mold-infested.

Unfortunately, once you notice this issue, the problem is too extensive, and you will need to replace your floorboards. It’s best to do this as soon as possible because rotten floorboards can pose a severe safety hazard.

How To Replace Your Floorboards

Replacing your floorboards is a big job, but it’s one that you can do yourself with a little bit of know-how.

Here’s what you’ll need:

  • New floorboards (you can purchase these at a lumberyard or DIY store)
  • A hammer and saw
  • Parquet glue
  • Spacers and a tapping block
  • Tape measure
  • A spade drill bit
  • Pry bar

Here is a step-by-step guide to replacing rotten floorboards in your house:

  1. Drills holes at each end of the rotten floorboards that need to be replaced.
  2. Cut the board in half in the center with a saw. Begin in front of one of the drilled holes, and then set the saw on the floor with the blade retracted until you reach the next hole.
  3. Use a hammer to lift the rotten floorboard, and use a pry bar to remove any nails you find. Remove the tongue from the end of the old board.
  4. Use a measuring tape to determine the dimensions of the space left by the lifted floorboard. Using these measurements, cut the new floorboard plank with a saw. Cut off the bottom of the groove with a utility knife to make the board fit over the tongue of the neighboring floorboard.
  5. Apply parquet glue under the new floorboard, and secure it in place.
  6. Use a rubber mallet to ensure the floorboard is firmly in place, and then place a heavy object on it.
  7. Allow 24 hours for the glue to dry before walking on the new floorboards.

2. The Floorboards Are Warping or Cupping

A common issue with hardwood floors is warping or cupping, which can cause them to rot. When your floorboards bend or bow in the middle, they are warping. In contrast, cupping refers to floorboards lifting from the edges and creating a cup-like shape.

Warping and cupping are caused by prolonged exposure to moisture, such as high humidity levels in your home. If your floorboards were not installed properly, they would be more prone to warping and cupping.

If your floorboards show signs of warping or cupping, you should have a professional inspect them to determine the cause. It’s best to replace incorrectly-installed floorboards because they will likely cause other problems in the future.

3. You Can See Mold or Mildew on the Floorboards

Rotten floorboards are a severe hazard because they are weak, and someone could trip or fall through them and injure themselves. Mold and mildew can also cause other health problems, such as respiratory issues and skin irritation.

Mold and mildew typically flourish in damp and dark areas. If the affected floorboards are in a humid room (such as the bathroom) or a dark area that doesn’t get much sun, they can quickly develop mold or mildew. Water leaks or spills can also cause this.

Below are the critical signs of mold and mildew growth on floorboards:

  • Black, brown, or gray spots or streaks
  • Furry or powdery growths
  • Musty smell

If you see mold or mildew on your floors, you should remove it immediately with a vacuum cleaner with a HEPA filter. Drying the area thoroughly to prevent it from growing again is also essential.

You can do this by using an absorbent towel to remove the excess moisture and then running a dehumidifier.

If your floor is severely affected by mold and mildew, you probably need to replace it.

4. Your Floorboards Are Splitting or Cracking

Rotten floorboards can split or crack as the wood weakens. When this happens, you will need to address the cause of the rotting and then replace the planks.

Fortunately, split or cracked floorboards don’t always signify rot damage. Dry air is the most common cause, and this is likely the case if:

  • The floorboards are close to an air conditioning or heating unit
  • The floorboards are in the same room as a fireplace or stove
  • Your home typically has low humidity levels

5. There Are Gaps Between the Floorboards

Gaps between floorboards can ruin the look of your floors and can be caused by any of the following issues:

  • Aging or shrinking wood
  • Incorrect floorboard installation
  • Excess moisture
  • Settling
  • Rotting floorboards

After noticing gaps developing in your floorboards, it’s best to have a professional inspect them and notify you of the underlying cause. If they confirm that it’s due to rotten floorboards, it’s important to take action as soon as possible to prevent the problem from worsening. A few ways to fix this problem include:

  • Using filler strips
  • Using shimming
  • Replacing the boards

Here’s a video that explains how to fix gaps on your floorboards by floor shimming:

6. Nails Are Popping Out of Your Floorboards

Nails popping out of boards is a sure sign of rotten floorboards. If you have this problem, it is important to fix it quickly. There are various ways you can do this:

  • Replace the affected floorboards. This is the most straightforward and effective way of fixing the problem. However, it can be time-consuming and expensive.
  • Repair the damage. You can do this using a putty knife and wood filler to fill in the gaps around the nails. This method is less effective but can save you time and money.
  • Cover the damage. This is the cheapest and easiest method and involves simply using a carpet or rug to cover the area. That said, this is best as a temporary option while waiting to execute options one or two.

7. The Floorboards Are Making Creaking or Popping Noises

It’s normal for floorboards to make creaking or cracking sounds as you walk over them, which is part of the appeal of having them. However, if your floorboards make unusual sounds, it’s a reason to be concerned because it may indicate that they’re rotten.

Floorboards are made of wood, which is a porous material. When water seeps into it, the wood swells and expands, causing the boards to warp and eventually break, resulting in noises.

Depending on the severity of the problem, you may need to replace certain or all of the floorboards.

8. The Floorboards Are Emitting a Bad Odor

If your floorboards no longer have their pleasant wood smell and are emitting an unpleasant odor, they are likely rotting. After noticing the bad smell, it’s essential to address it as soon as possible so that the issue doesn’t worsen.

You can either replace the floorboards or sand and refinish them. If you choose to sand and refinish the floorboards, you should remove the odor-causing particles before starting. This may involve removing the floorboards, drying out the underlying area, and using a vacuum cleaner with a HEPA filter.

9. Your Floorboards Are Infested With Insects

Insects are attracted to damp wood because they need moisture to survive. Therefore, if you have an insect infestation, it’s essential to check the floorboards’ moisture content to prevent further rotting.

Various insects can infest floorboards:

  • House Longhorn beetles
  • Carpet beetles
  • Termites
  • Death-watch beetles
  • Wood-boring weevils

These wood-loving insects also feed on the wood, and tiny holes in your floorboards is a common sign of infestation.

How To Eliminate Insects From Your Floorboards

If you have insects in your home, it’s crucial to eliminate them as soon as possible.

There are several ways to eliminate insects from your home, but the most effective method is to hire a professional exterminator. They have the knowledge and experience to get rid of insects quickly and efficiently.

In the meantime, there are a few things you can do to keep the insects at bay:

  1. Ensure you keep your floors clean and free of debris. Insects are attracted to food and dirt; the more food they have, the more likely they are to multiply.
  2. You can also try DIY methods, such as boric acid or diatomaceous earth. You can find these products at your local hardware store. Follow the directions carefully to avoid harming yourself or your family. This usually involves sprinkling a powder on the affected area or lifting the floorboards and treating the underlying area. You shouldn’t touch or walk over the floorboards while treating them.

10. Your Floorboards Are Old

Good quality wooden floors are a fantastic feature in any home; they can last for decades with the right care. However, even the best-kept floors will show their age over time.

Not maintaining your wooden floors can make them vulnerable to rotting, especially if they are several decades old. If your floorboards are old and you suspect rotting, have them inspected by a professional so that you can determine how to preserve them.

11. Your Floorboards Produce a Hollow Sound When Tapped

One of the telltale signs of rotten floorboards is a hollow sound when you tap on the floor. This is caused by the wood deteriorating and detaching from the joists. If you notice this, it’s essential to immediately remove the rotten floorboards before they collapse while someone walks over them.

As with the other steps, it’s essential to treat the cause of the rotting before repairing the floorboards.

12. Your Floorboards Have Collapsed

If you’re unlucky enough that your floorboards have collapsed, it could mean that they are rotten and weak. However, collapsed floorboards can also be due to a broken support beam or settling foundations, so it’s essential to verify the cause.

A floorboard professional can pinpoint the problem, advise you on how to fix it, and help you repair the collapsed floorboard section. In the worst-case scenario, you’ll need to repair a large section of the wooden floor.

13. Your Home Has Rising Damp

If your home has rising damp, and you don’t address the problem, there’s a good chance that your floorboards will eventually rot. Rising damp happens when the moisture in the ground below your house seeps upward and into your home’s structure.

Rising damp is more likely to happen if your home’s damp proofing is no longer effective. When new homes are built, they are treated with a damp-proofing product, but the homeowner will need to update it every few decades.

Fixing ineffective damp proofing is a job for professionals because it involves checking where the moisture is breaching. Once you’ve addressed the rising damp issue, you should dry out the floorboards and treat them with a waterproof varnish.


Floorboards can become rotten for various reasons. The most common signs of rotten floorboards are warping, cracking, or soft spots. Other signs include a musty smell, visible mold or mildew, and squeaking or creaking sounds.

If you suspect your floorboards are rotten, it is important to treat the cause and replace the affected boards before they cause any harm to you or your family. If you find the process challenging, you should contact a professional as soon as possible.


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