The Unfortunate Signs of Mold Under Vinyl Flooring

Say goodbye—your vinyl most likely won’t survive this

Interior view of a kitchen
Photo: John Keeble / Moment / Getty Images
Interior view of a kitchen
Photo: John Keeble / Moment / Getty Images
Highlights
  • Mold grows quickly under vinyl flooring, as it’s a perfect habitat. 

  • Prevention mainly involves constant humidity monitoring and ventilation.

  • Almost all mold carries health risks. 

  • Call a professional if you discover any mold. Don’t risk it.

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If your house smells musty, or you notice discoloration on your flooring, you may have mold under your vinyl flooring. Mold seldom remains hidden for long, so if you see mold creeping up from under your vinyl flooring–you’re probably looking at a much bigger problem. Mold is extremely toxic, so professional testing and removal is almost always required. 

Why is Mold Trapped Under Vinyl Flooring Dangerous? 

People are terrified of discovering mold, and for good reason. Once it takes hold it can spread rapidly, causing serious health complications (especially for those with compromised immune systems), and can wreak havoc on the structural parts of your house. 

When it comes to vinyl flooring, the minute you discover mold underneath it, that flooring is now garbage. Mold is stubborn and can grow from even the tiniest spore. Anything relatively cheap—like vinyl flooring—that is infected with mold should be discarded appropriately, as soon as possible. If you’re wondering whether or not you need a mold inspection, the answer is a resounding yes.

Health Risks

3 common mold types compared visually, including allergenic, pathogenic, and toxigenic
Images: Stephanie Rossow / Science Photo Library / Getty Images, Kateryna Kon / Science Photo Library / Getty Images, Dr_Microbe / iStock / Getty Images Plus

There are many types of mold and, unsurprisingly, none of them are good for you. Black mold is one of the more common varieties, and is one of the most toxic. Mold poisoning symptoms include, but are not limited to:

  • Shortness of breath

  • Brain fog

  • Respiratory distress, such as a persistent cough or phlegm 

  • Migraine 

  • Runny or stuffy nose 

  • Eye and skin irritation 

  • Fatigue. 

  • Gastrointestinal (GI) issues

If you experience any of these issues, and notice mold–either from sight or smell–visit a doctor immediately. In more serious cases, consider a hospital visit. These issues can develop very suddenly, or they could build over time. 

Structural Damage

Mold has a corrosive effect on the surfaces it inhabits. Mold feeds on moisture, and while you may think your wooden cabinets or vinyl flooring is dry, there is enough moisture present for mold to grow. This is especially true for vinyl flooring, which has a tendency to “gap” between the flooring and the base floor it’s placed on. 

Once the mold spreads, that’s an easy write-off for your vinyl flooring. However, it can also damage the underlying structure. Vinyl flooring is commonly placed over old hardwood, and mold will, over time, eat through the wood. 

Ideally, you will find this problem early, but vinyl flooring does a good job of masking mold growth. Mold is like cockroaches—if you see any signs or even one, it’s safe to assume there’s more. 

Why Does Mold Grow Under Vinyl Flooring?

Mold flourishes under vinyl flooring because it isn’t breathable, which leads to trapped moisture. The vinyl material acts as an impenetrable barrier that keeps moisture in place, creating the perfect breeding ground for mold growth. This is particularly true if the subfloor under the vinyl doesn’t have a proper moisture barrier.

Moisture can get under the vinyl flooring due to improper installation, water spills, leaks, or high humidity throughout the home.

Signs of Mold Under Vinyl Flooring

White wall with mold
Photo: Nicolas St-Germain / Adobe Stock

Smell

Mold smells. If you notice a musty smell in a room with vinyl flooring, that’s a dead giveaway that there’s growth under the flooring. While this isn’t good news, vinyl is easy to check under and rarely requires more than lifting a corner to check. Mold can also smell earthy (like mushrooms) or like rotting or decaying wood.

Pro Tip

If you can smell the odor and you can’t see it, usually that is a sign of something more serious. Mold can hide behind your walls and floors and will require a professional mold remediation company to run indoor air quality tests.

Marshall Schmitz

Owner, American Quality Restoration and Mold Remediation

Appearance 

There are a few signs mold is growing underneath your vinyl. Unfortunately, once you notice these signs, it means there is already a good amount of mold underneath. The only sign where this isn’t the case is when there are mold lines along the edge of the vinyl, as the mold may simply be growing in the space between the flooring and the wall. 

Other visible clues that—probably—indicate mold growth under your vinyl are:

  • Irregular bumps in the surface

  • Dark, splotchy patches that don’t clean off 

  • A border of mold along the edge of the vinyl 

  • Mold growing on the wall directly above the flooring

  • Seams opening

  • Adhesive deteriorating

Replacing and Repairing Mold-Damaged Vinyl Flooring

If the damage under your vinyl flooring was simply water damage, replacing it would be much easier. However, because you’re dealing with a toxic agent, you’ll need to call a mold inspector near you

Replacing and repairing should be done by a pro. Separating replacement and repair is a bit of a misnomer because, usually, they are one and the same. You can’t really repair vinyl flooring once it’s been tainted by mold, and it will need to be removed in its entirety. 

Professional mold removal costs between $1,100 and $3,300. This may seem high, but remember it isn’t just your floor that’s at risk—your health is far more important than saving a few bucks. 

Prevention Tactics

Preventing mold growth under your vinyl flooring isn’t as easy as preventing it from growing, say, under a kitchen cabinet. Mold needs moisture to grow, and it’s much harder to control moisture between two layers of flooring.

Your best bet would be to keep the humidity as close to 30% in your house as you can, and not higher. The reason for this is that mold likes to grow at humidity levels over 50%. Dehumidifiers and regular room ventilation are the two most powerful ways to prevent mold under your vinyl.

Other than preventative measures, react to any water issues immediately. Leaky pipes, water coming in through gaps, and any other water spills or pools need to be fixed as soon as you see them. A final step would be to conduct periodic mold inspections with a pro.

Frequently Asked Questions

If you have mold under your vinyl flooring, it’s recommended that you have it ripped out and start fresh. Mold isn’t something to take lightly and should involve a visit from a professional who can both test and identify the mold. If you’re determined to remedy it yourself, wear all the proper protective equipment—eye goggles, a high N-rated mask, and long, disposable gloves.

If you see black stuff under your vinyl flooring, it’s probably mold. There is a chance it could just be dirt, dried-out adhesive, or slight water damage, but some of those are causes for mold growth, so you should remove it immediately anyway. In some older homes, it could be black mastic asbestos. If you think it could be this–you guessed it–call a pro.

Mold grows at the fastest rate the environment it’s in will let it. The space between your vinyl flooring and the base flooring it’s on is a perfect environment for mold growth, allowing for rapid spread and contamination. Preventing this involves a proper installation of the flooring and constant humidity control.

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