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What Happens If Water Gets Under Waterproof Vinyl Flooring?

It’s never good when water gets under flooring, and the same holds for waterproof vinyl flooring. Waterproof vinyl flooring is often recommended for bathrooms and kitchens as it is water-resistant. Even though vinyl resists spills and water stains, you can minimize damage caused by water with some simple steps.

If water becomes trapped under waterproof vinyl flooring, it can cause extensive damage. The sub-floor may allow excess moisture to leak under the flooring, causing significant problems. Trapped water weakens the glue that is bonding the flooring, causes warping & bubbling, and encourages mold growth.

While water under flooring will cause damage and issues such as unhygienic mold growth, there are ways to prevent water from penetrating below your vinyl flooring.

Some general maintenance on spills will help prevent water stains, but larger problems such as leaks and subfloor issues will need to be dealt with. We’ll go through typical problems with trapped water under vinyl flooring and the solutions you can take for a damp-free floor.

What Happens If Water Gets Under Waterproof Vinyl Flooring?

Waterproof vinyl flooring is sometimes floated above a subfloor and sometimes glued directly to the subfloor. Each flooring option will have different issues regarding damp, and different approaches to fixing these issues.

There are several signs that water has become trapped under waterproof vinyl flooring that has been glued to the subfloor:

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  • The glue will begin to soften and deteriorate. Planks may move due to loosened glue.
  • Signs of damage include uneven surface, warping, bumps, and bubbles.
  • The edges of the vinyl pieces will lift as the flooring will no longer be successfully glued to the subfloor.
  • Seams start lifting or opening.
  • Pooled water may discolor your flooring.

Another problem related to water under vinyl flooring is that it encourages mold spores to grow.

Unfortunately, due to the nature of waterproof flooring, once water is trapped under the flooring, it becomes very hard to dry it out.

The lack of ventilation means natural air-drying will not occur, and you’ll have to help the drying process along. Depending on the severity, this could mean using fans to dry out the area or lifting the flooring completely.

If the damp problem is due to underflooring issues such as porous concrete, you may have to remove the flooring and treat the underfloor to seal it completely.

Can Mold Grow Under Vinyl Plank Flooring?

When water is trapped, it becomes stagnant and a breeding ground for mold and fungus. Water trapped in grooves, under the edges, and below the flooring will grow mold and mildew.

Usually, you can easily spot this mold growth, as even a small amount of mold or mildew will give your flooring a ‘dirty look.

You can test mold by using a diluted bleach mixture of 1 part bleach to 16 parts water. If you clean a spot on your flooring with this diluted bleach mixture, and the color lightens significantly, you likely have an underlying mold problem.

As long as moisture remains trapped under the flooring, mold spores will be reactivated, and the mold problem will not end. 

To prevent mold from returning, the underfloor must be thoroughly dried and the flooring surface treated to prevent any possible leaks through cracks, edges, or grooves.

QUICK TIP: It’s a good idea to invest in waterproof vinyl planking that has been permeated with mildewcides to help prevent the spread of mold.

Does Vinyl Plank Flooring Leak?

Vinyl flooring is designed to be water-resistant so that it can be used in rooms that tend to have a lot of water spillage, which is why it’s often recommended for basements, kitchens, and bathrooms.

However, if a vinyl floor is subjected to a continuous leak, that moisture will eventually find a way to permeate the waterproof barrier.

Vinyl plank flooring has been manufactured to provide an appealing and hard-wearing alternative to wood floors, and it will take a lot more water damage and spills than regular wood or bamboo.

The surface is extremely water-resistant, so you can easily wipe up spills and splashes without any effect on the appearance and integrity of the flooring.

If your flooring shows signs of discoloration, this is a sure sign that water has seeped under the flooring and damaged it.

While vinyl flooring does a great job with the usual spills and accidents caused by daily use, water will find a way to seep through if there is a major accident such as flooding or a constant, undetected leak and collect under the flooring.

How Does Water Get Under Waterproof Vinyl Flooring?

Though waterproof vinyl flooring is very durable and designed to be incredibly water-resistant, water can still get under it.

These are the major causes of water seeping under-flooring:

  • Spills or small leaks which have not been cleaned up.
  • Flooding accidents or overflow from a faulty machine or natural causes.
  • A constant leak from a machine such as a washing machine or dishwasher.
  • A hidden leak from plumbing for toilets, baths, or machinery.
  • Moisture from groundwater or crawlspaces.

It helps if you wipe up small spills quickly to prevent them from sitting on any bonding or adhesive. If you have faulty machines which cause constant leaks, they should be replaced or fixed. 

If your plumbing is a problem, it will need to be fixed as soon as possible to prevent further damage. The longer a problem related to water and damp is left untreated, the bigger it will become.

While a small area of dampness and damage can be easily treated, larger problems and affected areas may require more expensive solutions.

What Do You Do If You Get Water Under Vinyl Plank Flooring?

The steps you will need to take to remove water from under your flooring will depend on the extent of the problem and what has caused it.

If an area has flooded, your first step is to stop the cause of the flooding. Switch off any machines or faucets responsible. Repair any plumbing leaks.

You will want to dry the affected area as much as possible. Use mops and towels to soak up as much excess water as you can. Fans and dehumidifiers can help to circulate air and remove moisture.

If the flooding is relatively limited and the flooring has not been damaged, it may be enough to use fans and dehumidifiers to remove the last of the excess water.

If you don’t have access to fans or dehumidifiers, and the weather is good, you can improve drying time by opening windows and curtains to let in the sun and improve air circulation. It may take several days before the area is completely dry.

Unfortunately, if the damp and water are bad enough to have caused mold to grow and warping and bubbles to form on your flooring, you will have to remove and replace the vinyl flooring

Removing Water-Damaged Vinyl Flooring

If the flooding is extensive and long-term, you will likely have to lift all the vinyl flooring to dry the floor and possibly seal the subfloor.

Replacing your vinyl flooring is a rather big and time-intensive job, so ensure you have the tools and time. If the damages area is very large, you may prefer to call in builders rather than choosing DIY.

  • Vinyl flooring glued to the subfloor will require full removal and require a lot of effort to remove. Due to the nature of the adhesion, the flooring will very likely need to be replaced in its entirety.
  • Some adhesive vinyl floors are strip planks, which means you will be able to remove only the affected section rather than the entire vinyl floor.
  • Floating floors are usually waterproof vinyl planks that click together and require no tools or glue to fit them in place. These are the easiest to remove, and only the affected and damaged area needs to be lifted and replaced.

How to Lift Vinyl Flooring

  • Clear the area of furniture and machinery, so you have a clear space to work.
  • You will need to remove baseboards from the edges of your flooring carefully.
  • Most vinyl flooring is only glued down on the perimeter, and the center is left unglued. If the water damage hasn’t loosened the glue, you may need to use a pry bar or scraper.
  • It is easier to lift vinyl flooring if you cut it into 12-inch strips first. This assumes you will be completely replacing the viny flooring once the subfloor has been dried and repaired.
  • Pull up the vinyl, and fold the strips for disposal.

How to lift Waterproof Vinyl Floorboards

If there is only a small amount of damage to click lock vinyl floorboards, and your subfloor does not need to be replaced, your task will be easier.

You can remove separate planks and replace them with new planks once the subfloor has been dried. This video from Allure shows how to replace a single piece of click lock flooring:

How To Remove Water Under A Floating Floor

Once you have lifted your flooring, you will want to make sure the subfloor is completely dry. A dry floor will help prevent any future warping or damage. Mold spores will activate if the floor is not properly dried. This task can take several days to weeks.

NOTE: The time this task takes will depend on how much moisture is in the air, what tools you have available, and the amount of water absorbed by the sub-floor.

Take the following steps to ensure you have removed all the moisture before reinstalling your vinyl flooring.

  • Get rid of excess water with mops or extraction vacuums.
  • Set up dehumidifiers in the room to absorb excess moisture in the air. Here’s an example of a great dehumidifier on Amazon suitable for a 1750 square foot area.
  • You can run fans over the floor area to speed up the air-drying process. This drying time can take from 2 days to 2 weeks, depending on the dampness of the area.
  • You can test the humidity and moisture levels by using a moisture meter. You can buy one of these from Home Depot or this one from Amazon at a great price. 

Only once the floor is completely dry and any possible leaks sealed should you reinstall replacement vinyl floorboards.

How To Dry Out Subfloor

However, if the damp problem comes from your subfloor, you will have to remove your vinyl flooring and install a moisture barrier between the concrete subfloor and the floating floor.

Dry out your sub-floor with the use of a dehumidifier and fans. When drying, it is good practice to close off the room to limit the amount of air the dehumidifier has to process.

If your concrete subfloor is thoroughly cured and dried before the flooring is installed, this will help prevent moisture build-up.

Sometimes the position of the house and the concrete subfloor will lead to the floor absorbing moisture from runoff. Make sure you have adequate guttering and drainage that reroutes water away from the ground near your house.

High groundwater levels will also have a large impact on the dampness of your subfloor. If the damage is extensive and the subfloor is constantly damp, this job may not be suitable for DIY, and you will have to call in professional building help for a solution.

If the vinyl flooring is in a basement or laundry room affected by groundwater and rising damp, it may be worth it to invest in a dehumidifier for the room. A dehumidifier can remove 10-70 pints of water from the air a day, depending on the extent of the humidity.

There are definitely ways to keep your basement’s vinyl floors in good condition as long as you keep the moisture in check. Here’s an article I wrote about making vinyl flooring work for basements.

Sealing the Subfloor

Before laying down your new waterproof vinyl flooring, it’s a good plan to seal the sub-floor to prevent moisture from entering from below.

If you have a plywood sub-floor, you can caulk any gaps with silicone caulking, then seal the entire surface with a bonding agent or a waterproofing membrane you can paint on, such as RedGard (Amazon link).

You need not seal a concrete subfloor, but you can protect your vinyl flooring by installing a polyethylene film that will serve as a vapor barrier or moisture barrier.

Here’s a good option from Amazon which also has dozens of other uses around the home, garden, and garage.

This plastic sheeting slows down the moisture movement, preventing damp from damaging your floor. Install the vapor barrier on the concrete before laying down your waterproof vinyl flooring.


Waterproof vinyl flooring is designed to be attractive and resist spills and water damage, making it an excellent alternative to wooden or bamboo floors in kitchens and bathrooms.

If spills are not wiped up, and the floor is exposed to constant leaks from machinery and plumbing or damp from subfloors, it is possible that your vinyl flooring will need to be replaced. 

Long term water-damage causes glue deterioration, splits, warping floors, and encourages the growth of mold. That’s why it’s important to address the causes of damp and leaks and get the subfloor completely dried before replacing the damaged vinyl flooring.