How to Fix 5 Likely Causes of a Spongy Laminate Floor


If you’re walking on your laminate floor and you suddenly notice an area or a portion of it dipping, feeling squishy, having a soft spot, having some bulging or air bubbles, or unnaturally spongy when you step on it, it may just be a minor problem that can easily be fixed or it can also be a sign of a much bigger problem underneath the floor that should be addressed immediately. Whatever the case may be, you first need to identify the root cause of the dipping or spongy portion of the floor to be able to address it appropriately.

Why does your laminate flooring feel spongy? A laminate floor that feels spongy can be caused by any of these 5 conditions: an uneven sub-floor, an underlayment issue, an expansion gap issue, water damage, or termite damage. While some of them can be addressed easily, you may still need to hire professionals to help you out.

Once you’ve identified the root cause of the spongy or squishy area on your laminate, it would be easier to figure out how to deal with the problem.

It is also worth mentioning that an improper acclimation of the laminate floors prior to the installation could lead to soft spots overtime. You can learn more about acclimation in this article.

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5 Likely Causes Why Your Laminate Floor has Soft Spots and Feels Spongy, and How to Fix Them

As mentioned above, laminate flooring that feels spongy, squishy, or soft can be caused by any one, or combinations, of the reasons below. Effectively assessing the root cause of the soft spots or spongy areas of the laminate, you will be able to address it with an appropriate and efficient solution and mitigating any trial and error actions on your part.

1. Soft spots on Laminate Flooring Caused by an Uneven Sub-floor

Laminate flooring requires a flat and an even sub-floor for its proper installation. If you install laminate over an uneven sub-floor, with it being generally thin, any imperfections on the sub-floor may telegraph to the laminate flooring and may even cause those soft spots to happen.

In an uneven sub-floor, whether it be concrete or wood sheet, soft spots or the spongy areas of the laminate can happen in areas where the laminate is hanging flat while the sub-floor underneath it is dipped or having a low spot, creating an air gap in between them. This can cause the laminate to flex or dip when stepped on.

On a tongue and groove wood sub-floor, there may be floorboards that are not securely attached to the floor joists that has some movement, or allow a slight give when walked upon. Any floorboards that are creating these movements, if not secured properly before installing the laminate, will telegraph on to the laminate. This can cause the soft spots or spongy areas to happen on the laminate floor where the floorboards underneath moves.

How to know if an uneven sub-floor is the cause of the soft spots or spongy areas of your laminate?

You’ll know if an uneven sub-floor is the possible cause of the soft spots or spongy areas of your laminate if the laminate flooring is newly installed and one or a combination of the conditions below are true:

  1. The sub-floor is concrete, OSB, or plywood, and there were some minor dips or low points that were not addressed before the laminate installation.
  2. The soft spot or spongy area is relatively flat, not bulging or peaking, when not stepped on but flexes and dips down more than other areas of the floor when you step on it.
  3. The sub-floor is tongue and groove wood and there were floorboards that have some movements in them when walked upon which were not secured properly before the laminate installation.

How to Fix a Soft Spot on Laminate Floor Caused by an Uneven Sub-floor

There are three methods you can try to address an uneven sub-floor causing those soft spots on your laminate floor.

For the first method, you’ll need a drill with a 3/32″ drill bit, an air inflator needle used for inflating balls, and a can of expanding spray foam.

The idea is to drill a small hole, just enough to fit the air inflator needle, and inject the expanding foam under the planks to fill in any air gaps underneath the laminate. Below are the quick steps:

  1. Locate where the soft spots are and put down a layer of masking or painter’s tape to protect the surface of the laminate.
  2. Drill a small hole, on a floor seam, using the 3/32″ drill bit.
  3. Attach the air inflator needle to the tubing nozzle of the expanding foam spray can.
  4. Carefully insert the air inflator needle and inject the expanding foam into the small hole until it fills the air gap underneath and the laminate feels properly supported.
  5. Remove any excess foam and then cover the small hole with duct tape until the foam sets.
  6. Remove the duct tape and fill the small hole with a matching color wood putty.
  7. Repeat this to other soft spots of the laminate.

This is the fastest method but not necessarily the best as you will have to drill a hole to your laminate and the expanding foam may cause unnecessary bulging if it were applied too much. Make sure to test the expanding foam first, see how it works, so that you’ll have an idea how much to apply and when to stop.

Here’s a video showing how this is done:

If you have access to the floor joists and the sub-floor from below, you can inject the expanding foam from below instead. Just add a sheet of plywood over the soft spots on your laminate and then add some weight over it. This will help prevent the expanding foam from pushing up too much.

The second method will require you to remove your laminate flooring partially, where there are dips or low point in your sub-floor. You will then apply a thinset mortar to the low areas of the sub-floor until it levels with the rest. If you have a wood sub-floor, make sure you’re using a thinset mortar designed to be used on woods.

Below is a video how this can be done:

The third method is for when you have tongue and groove floorboards used as a sub-floor that was not securely fixed. You will also need to remove your laminate flooring partially to access the floorboards. Walk around and look for areas of the sub-floor that has some movements and secure them down to the floor joist with a 2-inch decking screw. You may need to use more than 1 screw to effectively secure it.

Make sure there are no more floorboard movements when you install back the laminates. And if there are some low points on the floor, you can also apply a thinset mortar on those areas as how it was described in the second method written above.

2. Soft Spot on Laminate Flooring Caused by an Improper Underlayment Installation

An underlayment can be a cause of a soft spot or spongy area on your laminate if you’ve used the wrong type or if it was installed incorrectly.

Only underlayments specific for laminate flooring use can be used. Other types, like the ones used for carpets, may be too soft or too thick for laminates which will cause it to feel spongy.

Using more than one layer of underlayment underneath the laminate can also make the flooring too soft and will create unnecessary soft spots and spongy areas on the floor. You can read more about it in this article.

If the underlayment was not laid flat or parts of it are overlapping with another part of the underlayment, this will cause an uneven base and may also cause soft spots in your laminate.

If the laminate was newly installed and you are aware that the underlayment used was the wrong type or it was applied incorrectly, then the only solution to this is to redo the whole laminate flooring.

Remove the laminate carefully, reapply the correct type of underlayment type and apply the proper installation methodology, and then reinstall back the laminate over the underlayment.

3. Soft Spot or Bubbling on Laminate Caused by Lack of Expansion Gap

If there are areas of your laminate that are lifting or seems like it has been filled with an air bubble underneath, and the bulge migrates to another area of the floor when you step on it, it is most likely caused by a lack of expansion gap provided during installation.

An expansion gap is normally provided where the laminate edge meets the wall. It is also provided where the laminate edge meets the edge of another flooring. The gap is normally covered with a transition strip to keep it looking neat and clean. The expansion gap will allow the laminate to move and naturally contract and expand. Basically, the expansion gap helps it to move and float freely.

In big rooms or areas where a laminate flooring is to be installed, an expansion gap or joint should also be provided every 27′ or 8m in both directions of the floor. This helps relieve pressures that would cause the laminate planks from pushing against each other and causing the seams to lift if it were not provided. The spacing of the expansion joints may differ from product to product so you should always refer to the standards of the manufacturer.

Also, make sure that your laminate flooring is not fixed or nailed down anywhere on the floor as this could prevent it from moving freely and will also cause bubbling or planks peaking. Sometimes, a molding that has been installed at the edge of the floor may have been nailed to the sub-floor with the laminate, accidentally, getting fixed along with it. Here’s a good article to read regarding why nailing or gluing down laminate flooring is not recommended.

To fix this, follow where the peaking is happening and go the the closest wall. Carefully remove the molding to reveal the corner where the edge of the laminate floor and the wall meets. Then cut-out the part of the laminate that is pushing against the wall, providing a gap that is around 1/4″ or 6mm in between the edge of the laminate and the wall. Check if the bulging gets fixed and then reinstall the molding back, making sure you do not drive the nail into the laminate. The peaking might not settle right away and you may have to place weights over it until it does.

Here’s a video demonstrating this fix:

4. Squishy or Spongy Laminate Caused by Water Damage

A squishy and spongy laminate can be caused by water damage. There can be several causes of water damage to laminate flooring which includes mopping the floor with a very wet mop, getting flooded from burst plumbing pipes, and insufficient moisture barrier installed underneath.

A damaged laminate plank cannot be fixed and the only option is to completely replace it. Once it gets saturated with water, it expands and gets soft, and will no longer be usable as a floor.

Whichever the cause of the water damage is, you should address it first before you reinstall a new laminate to prevent another water damage from happening again. This can mean fixing a burst plumbing pipe or installing a new moisture barrier.

If the floor got flooded, it is also best to check the sub-floor and the floor joists. Make sure that they are still in peak conditions and were not compromised.

Plywood or oriented strand board sheets sub-floors are susceptible to delamination when it gets saturated with water. When they get delaminated, the glue that holds the layers of the sheets together releases which can cause it to swell. The swelling can translate back to the laminate flooring, making it feel soft and spongy.

Sub-floors and structural members that have been compromised by water damage must be replaced or repaired before you reinstall your laminate flooring. Damages that involve sub-floors and floor joists is recommended that it be checked by a consultant and worked on by professionals.

5. Soft and Spongy Laminate Caused by Termite Damage

Termite damage can also cause the laminate flooring to get spongy or soft. If the floor has been installed for a long time and it suddenly became soft on some areas, and you ruled out water damage, termites might have penetrated the floor. If you have termites in your floor, you will usually find wood dust forming near the soft areas, and sometimes you’ll notice that some parts of the laminate are starting to disintegrate.

If it is termite damage, the laminate planks that got affected are completely unusable and you have no choice but to replace them.

Similar to how you address water damage, you would need to address the cause of the damage, which is the termites, before you replace and install new laminate planks. Also check if the termites got to your floor joists and structural wood members as well. Make sure they were not compromised, otherwise you would have to replace them as well.

You’ll need to hire professionals to help you with your termite problem, and to help you assess the structural stability of the floor and fix it if there were any problems.

Angelo

He is an architect for more than 20 years. He is passionate about design and architecture and enjoys sharing his knowledge and information with people as well.

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