Dehumidifier for Mould Australia: How to Choose, Use & Control Mould 2

Mould thrives when indoor humidity stays above 60% and can damage property, contents and health. A dehumidifier for mould lowers humidity so mould struggles to grow and spores settle. This guide covers how to choose and use a mould dehumidifier in Australia—including LGR and desiccant options—plus target humidity levels, sizing and where to buy ASA/SAA units from Thorair.

Why Use a Dehumidifier for Mould?

Stops growth

Mould needs moisture to grow. Keeping relative humidity under 50–55% removes that condition so existing mould stops spreading and new growth is discouraged.

Reduces spores

Lower humidity helps spores settle and makes the air less suitable for mould. In affected rooms, dehumidification supports cleaning and remediation.

Protects property

Excess moisture warps timber, blisters paint and degrades materials. Controlling humidity helps protect walls, joinery, flooring and stored items.

Improves air quality

Less mould and moisture mean fewer allergens and musty smells, which is especially important for asthma, allergies and general comfort.

Mould, Humidity and How Dehumidifiers Help

The link between humidity and mould

Mould grows when relative humidity stays high for long periods—often above 60%, and in cooler, poorly ventilated spots. Condensation on windows, cold walls and in cupboards creates microclimates where mould can establish even if the rest of the room feels okay. A dehumidifier removes moisture from the air so these areas stay drier and less hospitable to mould.

Target humidity to prevent mould

For mould prevention, aim for 45–55% relative humidity indoors. Under 50% is often recommended in damp or previously affected areas. Many dehumidifiers have a humidistat; set it to 50% or lower and run the unit until levels are stable. Monitor with a hygrometer in problem rooms.

After water damage or flooding

After leaks, floods or severe condensation, structural materials and furnishings can hold a lot of moisture. Professional water damage restoration often uses high-capacity commercial dehumidifiers (e.g. 50L–90L per day) to dry buildings quickly and limit mould. For smaller jobs, a robust domestic or light-commercial unit can help if run early and consistently.

Types of Dehumidifiers for Mould in Australia

LGR (low-grain refrigerant) dehumidifiers

LGR dehumidifiers work well in cooler, damper conditions—common in mould-prone areas like basements, laundries and southern Australian climates. They pull more moisture per hour at lower temperatures than standard refrigerant units, so they’re a strong choice for mould control in unheated or partly heated spaces.

Effective from around 10–15°C upwards
Good for cooler, damp rooms and subfloors
Higher moisture removal in mould-risk conditions
Widely used in restoration and commercial settings

Desiccant dehumidifiers

Desiccant units work by absorbing moisture into a rotating wheel. They perform well in cold conditions (often down to 1°C or below) and in low-humidity, cold environments where refrigerant models are less effective. Useful for cold storage, unheated sheds, or mould in very cool spots.

Works in cold and very low humidity
Suits cold rooms, cellars and unheated areas
Can achieve very low RH when needed
Different technology to LGR—choose by temperature and use

Standard refrigerant dehumidifiers

Standard refrigerant (compressor) dehumidifiers are cost-effective and work well in warmer, humid conditions—typical in many Australian homes. They are less effective in cool, damp mould hotspots. For mould in living areas, bathrooms and well-heated spaces, a correctly sized refrigerant or LGR unit is usually sufficient.

Best in warmer, humid conditions (e.g. 18°C+)
Good for living areas, laundries and enclosed spaces
Often lower purchase cost; check daily L/day capacity
Ensure ASA/SAA approval for safe use in Australia

Sizing a Dehumidifier for Mould

Capacity (litres per day) should match room size and dampness. More moisture, larger space or cooler conditions usually need a bigger unit. The following are typical starting points; severe mould or water damage may require commercial-grade dehumidifiers.

20–30L/daySmall rooms

Single bedrooms, small bathrooms, under-stair cupboards. Good for localised damp and light mould prevention.

50–70L/dayMedium to large

Large bedrooms, open living areas, laundries, double garages. Suits moderate mould risk and post–water-damage drying in average homes.

70–90L/dayLarge / commercial

Whole homes, basements, large crawl spaces, small commercial buildings. For heavy mould, restoration work or very damp, cool spaces.

Benefits of Using a Dehumidifier for Mould

Prevention

Maintaining 45–55% RH in problem areas reduces the chance of new mould and limits regrowth after remediation.

Support for cleanup

Dehumidification supports cleaning and removal of mould by keeping surfaces and air drier during and after treatment.

Protection of contents

Lower humidity helps protect furniture, fabrics, documents and stored goods from mould and moisture damage.

Year-round control

In humid coastal and subtropical regions, running a dehumidifier in key rooms helps maintain stable, mould-unfriendly conditions.

Where to Use a Dehumidifier for Mould

Bathrooms & laundries

Steam and poor ventilation create ideal mould conditions. Use a dehumidifier during and after bathing or drying clothes, or continuously in very damp setups.

Bedrooms & wardrobes

Condensation on windows and in built-in robes encourages mould. A unit in the room or ducted into the wardrobe can keep humidity down.

Basements & crawl spaces

Cool, often unventilated and damp. LGR or desiccant dehumidifiers are well suited. Size for the full volume and run consistently.

After water damage

Floods, leaks and burst pipes wet structure and furnishings. Pair water damage restoration with high-capacity dehumidifiers (and air movers if needed) for faster, more thorough drying and mould prevention.

Tips for Using a Dehumidifier for Mould

Set and hold 50% or lower

Use the humidistat at 45–50% in mould-prone areas. Check with a hygrometer and adjust run times or capacity if needed.

Run it continuously in problem zones

For active mould or high risk, run the dehumidifier 24/7 until humidity is stable, then as needed to maintain levels.

Empty and maintain the unit

Empty the tank or use a drain hose. Keep filters and coils clean so the unit performs reliably and doesn’t become a moisture or dust source.

Improve ventilation where possible

Use exhaust fans, open windows when weather allows, and avoid blocking vents. Dehumidifiers work best alongside basic ventilation.

Australian Standards: ASA/SAA Dehumidifiers

For safe, legal use in Australia, choose dehumidifiers that meet Australian Standard (ASA/SAA) requirements. Thorair’s dehumidifier range includes ASA/SAA-approved LGR and commercial units suitable for mould control and restoration.

Look for ASA or SAA compliance on the unit or product listing.
Non-compliant imports can pose electrical and safety risks.
Commercial and restoration-grade units should also meet local workplace and electrical standards.

Dehumidifier for Mould: FAQs

What humidity level stops mould?

Keeping indoor relative humidity at or below 50–55% significantly slows or stops mould growth. In damp or previously affected areas, many professionals aim for 45–50% or lower. Use a humidistat and a hygrometer to monitor.

Is an LGR dehumidifier better for mould?

LGR (low-grain refrigerant) dehumidifiers are often better in cool, damp conditions where mould is common—e.g. basements, laundries, southern Australian climates. They remove more moisture at lower temperatures than standard refrigerant units. In warmer, humid rooms, a well-sized standard or LGR unit can both work.

Can a dehumidifier remove existing mould?

A dehumidifier does not kill or remove mould; it reduces humidity so mould struggles to grow and spores are less likely to spread. You still need to clean or remediate visible mould. Dehumidification supports that work and helps prevent regrowth.

How big a dehumidifier do I need for a mouldy room?

Depends on room size, how damp it is and temperature. A 50–70L/day unit is often suitable for medium to large mould-affected rooms or post–water-damage drying in an average home. Smaller rooms may need 20–30L/day; whole homes or commercial spaces may need 70–90L/day or multiple units. For severe mould or restoration, consider commercial dehumidifiers and professional advice.

Where can I buy a dehumidifier for mould in Australia?

Thorair supplies ASA/SAA dehumidifiers for mould control, water damage restoration and commercial use. View the dehumidifiers collection, or contact us on 1300 263 551 or info@thorair.com.au. Free delivery on orders over $2,000.

Shop Dehumidifiers for Mould at Thorair

Control mould with the right humidity and capacity. Explore our dehumidifiers—including LGR and commercial ASA/SAA units—or speak to our team on 1300 263 551 or info@thorair.com.au. Free delivery on orders over $2,000.

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