Does a dehumidifier help with mould? Appliance experts share honest answers

During winter, it's hard to keep thoughts of mould, moisture and damp off your mind as a homeowner. But could investing in a dehumidifier be the mould solution you've been looking for?

It's no secret that owning one of the best dehumidifiers on the market is not only fantastic for drying clothes indoors but also helps significantly with reducing the humidity in your home. However, what are its capabilities when it comes to stopping mould growth?

No one wants to deal with mould, and the best way to stop it is to prevent it, which is why we spoke to leading appliance experts to get the lowdown. Can running a dehumidifier really help with mould growth?

Does a dehumidifier help with mould?

If you've been looking for ways to prevent mould in your home, you've no doubt come across dehumidifiers. They're as popular as ever and for good reason, but are they actually helpful to stop those dread black spores?

"It's one of the most effective first steps against household mould. It actively lowers indoor relative humidity, removing the conditions that mould needs to grow and helping keep condensation off cold surfaces," says Mike Bekin, Managing Director at Ecochoice. "Used correctly, it helps prevent new colonies forming and protects finishes like plaster, paint, hardwood floors and sustainable timber joinery from recurring damp patches."

"Pick the right type for the space: a compressor model is usually most efficient for heated rooms, while a desiccant unit performs better in cooler, unheated areas. Keep a simple hygrometer in the room and aim for 40–60% relative humidity for a steady, preventive result," he adds.

It's all too easy to forget the unexpected places mould may be hiding, which usually means you find it when it's too late to prevent or easily treat. Having a dehumidifier running can be a big help in reducing those mould discoveries.

"It removes the moisture from the air so surfaces stay dry enough that spores can’t take hold. A dehumidifier pulls water vapour from the air and lowers the dew point, so less moisture condenses on windows, external walls, and window sills, and any existing damp patches dry faster by evaporation. Place it near the problem area with doors and windows closed, use a laundry mode or higher fan when drying clothes, and set it to maintain around 50% RH," explains Mike.

"In unheated garages, garden rooms or utility spaces, common spots for musty smells around exterior timber or stored materials, a desiccant unit is the better choice; in normal living rooms and bedrooms, a compressor unit is more economical. Combined with regular ventilation and source control, this is how a dehumidifier breaks the cycle that feeds mould growth," he continues.

Knowing the right size dehumidifier for your home will also make a huge difference in maintaining a safe, healthy humidity level, no matter the room.

Mike Bekin

Mike is a construction and home improvement expert with over 20 years of experience working with timber and building materials across residential projects. As the founder of Ecochoice, he has advised homeowners, builders and designers on choosing materials for homes and gardens that balance durability, appearance and longevity.

Should I use a dehumidifier if I have mould?

If you have already discovered spores in your home, whether it's pink mould in the bathroom or black on your walls, buying a dehumidifier is unfortunately not the quick fix you may think it is.

"People switch on a dehumidifier and expect existing mould to disappear, but it won’t remove what’s already grown. You should use it if you have mould, but first clean the visible growth and deal with the cause, whether that’s a bathroom without enough extraction, a leaking pipe, or rain ingress through defective pointing or timber cladding," suggests Mike.

"After cleaning, run the dehumidifier to hold 40–60% RH while you improve ventilation and repair defects, which prevents quick regrowth on plaster, sealants and timber trims. If you suspect penetrating or rising damp, bring in a competent surveyor because an appliance can’t fix water coming through walls or up from the ground. Used as part of that plan, the dehumidifier stabilises conditions so your remedial work actually lasts," he says.

When you're completing your daily cleaning habits, it's a good idea to keep an eye out for any early signs of damp or mould. That way, you're more likely to find it before it gets out of hand.

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FAQs

Do dehumidifiers take damp out of walls?

Knowing how to use a dehumidifier in the winter, especially, will be a huge help with reducing moisture buildup in your walls. Damp walls can lead to a world of challenges, and it's difficult to treat once it's started.

"If left untreated, damp and mould can cause damage to both health and home. It thrives under damp, warm, indoor conditions and spreads through the air as mould spores," starts Chris Michael, Meaco's Chief Product Officer. "Combating mould requires a combination of treatment and preventive measures. The addition of a dehumidifier with a HEPA filter air purification function will help to reduce moisture and remove remaining mould spores from the air."

"Mould, which is a type of fungi, will form on a surface when its moisture content is too high. The rate at which the mould grows will be determined by the room’s relative humidity (RH). If it is above 68% RH, then mould will form and spread, but if it is below 68% RH, then it will stop," he adds.

Chris goes on to explain that a dehumidifier will draw out the damp from walls, as well as from the air, while improving air quality for the occupants.

Chris Michael

Chris co-founded Meaco with his partner Michele back in 1991. Since then, they've expanded the brand to cover all air quality needs, from dehumidifying to air purifying. Their products have won awards for their quality.

What's better for mould, an air purifier or a dehumidifier?

Should you be debating whether one of the best air purifiers would be a better investment, we asked Chris which appliance is more suited for tackling mould.

"An air purifier with a HEPA filter will capture and trap airborne mould spores, preventing them spread. However, as air purifiers don't remove the moisture from the air, they have a limited impact on mould growth," begins Chris.

"The ideal solution is a dehumidifier with HEPA air purification capabilities - a two-in-one appliance, saving the outlay and running costs on a secondary device. This is preferable to a regular dehumidifier as the dust filter they come with does not trap mould spores," he finishes.

If you really want to keep the mould away, it's important to stay on top of the things to declutter than can cause damp. Sometimes, cluttered, cramped spaces are the perfect home for moisture and inevitably mould growth.