It is frustrating, especially when different websites give completely different advice. One says heat will solve it. Another says mould can survive surprisingly high temperatures. Then there is the familiar claim that 60°C is the magic number.
For a homeowner, none of that is especially helpful when the real question is much simpler. What actually works when mould is already growing in your home?
The answer depends on more than the number on a thermostat, and understanding that difference can save you from wasting time on fixes that only deal with the surface.
Does Heat Kill Mould?
Heat can kill or inactivate mould, but only when the contaminated material itself becomes hot enough for long enough. Warming the air around it is a very different thing.
If your thermostat reads 22°C, the plasterboard behind a mould patch may not be anywhere near that temperature. The same applies to timber, insulation, wallpaper adhesive, and other porous materials where fungal growth can extend beneath the visible surface.
There is also no reliable household rule that says 60°C kills all mould. Laboratory research has shown thermal inactivation of Aspergillus niger spores around this range, but fungal heat resistance varies, and some specialised heat-resistant spores can survive much higher temperatures.
More importantly, killing mould is not the same as getting rid of it. The EPA warns that dead mould can still cause allergic reactions, so contaminated material still needs to be cleaned or removed and the moisture problem corrected.
What Temperature Kills Mould?
You will often see 60°C or 140°F described as the temperature that kills mould. Research does show thermal inactivation of some fungal spores around this range, including Aspergillus niger, but it is not a universal cut-off.
Species, spore type, exposure time, moisture, and the material itself all change how mould responds to heat. Some heat-resistant ascospores have survived processing at 80°C to 90°C, which shows why laboratory temperatures should not become DIY instructions for heating walls or furniture.
| Temperature or situation | What it means for mould |
|---|---|
| 18 to 25°C room | Will not kill established mould. Warmer surfaces may reduce condensation. |
| Warm surface near a heater | May dry the surface, but does not provide reliable remediation. |
| Around 60°C | Can inactivate some fungi under controlled conditions, not all mould. |
| 70 to 90°C | More damaging to many fungi, although resistant spores may survive. |
| Steam or boiling temperatures | Can destroy fungi where sufficient heat reaches them, but time and penetration still matter. |
| Professional thermal treatment | Uses controlled temperatures, monitoring, and set exposure periods rather than domestic heating. |
Will Turning the Heating Up Kill Mould?
No. Setting your thermostat to 20°C, 22°C or even 25°C will not sterilise mould growing on a wall. Domestic central heating does not raise contaminated materials to the temperatures needed for reliable thermal inactivation.
Heating still matters because condensation forms when moisture-laden air reaches a sufficiently cold surface. Keeping walls and ceilings warmer can reduce that risk, which helps explain why mould often develops around window reveals, external corners, cold bedrooms and behind furniture where surfaces stay cooler, and air movement is limited.
UK government guidance identifies low internal wall temperatures, ineffective heating, inadequate insulation and poor ventilation as factors that should be investigated when damp and mould occur.
Heating also lowers relative humidity when the amount of water vapour stays the same, but it does not remove moisture from your home. That moisture still needs to be controlled through:
- Ventilation and extractor fans
- Dehumidification where appropriate
- Reducing moisture from indoor laundry and cooking
- Repairing leaks or other sources of water
Energy Saving Trust likewise recommends tackling moisture build-up, improving ventilation and dealing with the underlying cause rather than relying on heating alone.
Heater, Dehumidifier, Hair Dryer or Steam: What Actually Works Against Mould?
These devices are often grouped together because they involve heat or drying, but they do very different jobs.
Heat changes temperature, dehumidification removes water from the air, ventilation removes moisture-laden air, cleaning removes contamination, and repairs stop new water from entering.
| Method | Can it kill or inactivate some mould? | Removes existing mould? | Removes moisture? | Useful for a home mould problem? |
|---|---|---|---|---|
| Central heating | Not at normal room temperatures | No | No | Helps reduce condensation risk, but does not remove mould |
| Space heater | Possibly at extreme local surface temperatures | No | No | Not a mould treatment |
| Hair dryer | Possibly on a very small directly heated area | No | No | No |
| Heat gun | Can reach temperatures capable of damaging fungi | No | No | No, due to fire and material damage risks |
| Steam | Yes, with enough heat and contact time | May loosen surface contamination | No, and it can add moisture | Limited to suitable surfaces |
| Dehumidifier | No | No | Yes | Useful where excess humidity is contributing to mould |
| Mechanical cleaning | Not necessarily | Yes | No | A core part of mould removal |
| Ventilation or extraction | No | No | Removes indoor water vapour | Important where condensation is involved |
| Repairing a leak | No | No | Stops new moisture entering | Essential when a leak is the cause |
| Professional thermal treatment | Yes, when properly controlled | Cleanup may still be needed | Depends on the process | Specialist use only |
No single appliance does everything. The right approach depends on whether you need to remove mould, lower humidity, improve airflow, or stop water entering the property.
Does a Space Heater Kill Mould?
A space heater can warm the room and the surface directly in front of it, but that does not mean the entire mould colony reaches a temperature capable of inactivating it.
The distinction between air temperature, surface temperature and the temperature inside a material matters here. Hot air blowing onto painted plasterboard may warm the face of the wall while dampness or mould behind the board, wallpaper or inside a cavity remains much cooler.
A space heater can assist drying once the moisture source has been dealt with. It should not be treated as a method for removing mould.
Does a Hair Dryer Kill Mould?
A hair dryer can make a small patch of material very warm, but the temperature changes constantly and heat does not penetrate porous materials evenly.
Even if some fungal cells are damaged, the remaining spores, hyphae, fragments, and staining are still present. Blowing high-speed air directly at visible mould may also disturb contaminated material and release particles into the room.
For household mould remediation, a hair dryer offers little benefit and is not needed.
Does Steam Kill Mould?
Hot steam can inactivate fungal structures when enough heat reaches them for sufficient time. That does not automatically make steam suitable for treating mould in a building.
Steam introduces additional water, which can be a problem on plasterboard, insulation, carpet and some timber. If those materials are already damp, repeated steaming may make the moisture problem worse.
Steam may have a limited role on suitable hard surfaces that can be cleaned and dried quickly, but it should not be treated as a universal solution for mouldy walls.
Does a Dehumidifier Kill Mould?
No. A dehumidifier does not kill mould that is already growing, but it can be far more useful when excess indoor humidity is contributing to condensation.
Instead of adding heat, it removes water from the air. The CDC recommends keeping household humidity no higher than 50% where practical, although surface conditions still matter.
A hygrometer in the middle of a room can therefore show an acceptable reading while a cold external corner remains damp enough for mould. The air immediately beside that colder surface can have much higher local relative humidity.
Existing mould still needs appropriate removal, while the moisture conditions encouraging regrowth also need to be corrected.
Why Killing Mould With Heat Does Not Solve the Problem
Even if heat successfully stops mould from growing, the contaminated material is still contaminated. Dead spores, fungal fragments, staining and allergens can remain on or inside the surface, especially with porous materials such as plasterboard, timber and fabrics.
That residue matters because it can still be disturbed and released into the air. EPA guidance notes that dead mould may continue to cause allergic reactions, which is why successful remediation involves removal rather than simply making the fungus non-viable.
The other half of the problem is moisture. If a wall stays damp because of condensation, a leak, poor ventilation, or another unresolved cause, treating the visible patch only changes what you can see. New growth can develop once conditions become favourable again.
So the real goal is not to kill mould in place. It is to remove the contamination and correct the condition that allowed it to grow.
What Should You Do Instead of Trying to Kill Mould With Heat?
1. Find Out Why the Area Is Wet
Start with the damp pattern, not the mould itself. Mould in a cold external corner often points towards condensation, while staining that worsens after rain can suggest penetrating damp. Damp beside pipework, below a bathroom or beneath a roofline may point to a leak instead.
The location, timing and condition of the surface usually tell you more than the colour of the mould. Check for cold walls, damaged plaster, tide marks, leaking gutters, poor extraction and insulation gaps before choosing a treatment.
If the source is not obvious or the same patch keeps returning, a Weather Wise damp survey can help identify whether the problem is condensation, water ingress, rising damp, inadequate insulation or another moisture issue.
2. Stop or Control the Moisture Source
What you do next depends on where the water is coming from. Repair leaking pipework, roofing or gutters if water is entering the building. If showers or cooking are driving humidity, check that extraction works properly and keep trickle vents or other background ventilation open.
A dehumidifier can help where indoor humidity stays high, but recurring condensation on a cold external wall may point to poor insulation or a thermal bridge. In that case, removing moisture from the air alone may not be enough.
3. Remove the Existing Mould Appropriately
Once the moisture source is under control, the existing contamination still needs attention. Mould on washable, non-porous surfaces can often be physically cleaned, while badly affected porous materials may be much harder to salvage because growth can extend below the surface.
If mould is widespread, concealed, repeatedly returning or affecting damaged plasterboard, insulation or other absorbent materials, professional assessment may be more appropriate than repeated surface cleaning.
4. Dry the Area and Prevent It Becoming Wet Again
Drying matters after cleanup, but only once the source of moisture has been dealt with. Depending on the cause, that may involve extraction, ventilation, dehumidification or suitable heating.
In condensation-prone rooms, heating and ventilation often work together. Warmer surfaces are less likely to collect condensation, while ventilation removes water vapour before it settles.
Leave some space behind furniture placed against cold external walls as well, since trapped air can create colder, more humid pockets where mould is more likely to return.
When Should You Get Professional Help With Mould?
If you have tried heating, drying or cleaning the area and the mould keeps returning, the problem is unlikely to be solved by heat alone.
Get professional help when:
- The mould is spreading or affecting several rooms
- Walls or other materials remain damp
- There is a persistent musty smell with no obvious source
- Mould appears to be hidden behind wallpaper, plasterboard, flooring or fitted units
- Water ingress or another building defect may be involved
- You cannot tell whether the cause is condensation, penetrating damp, rising damp or something else
Larger or concealed mould problems may also need professional removal. The important point is to diagnose the moisture source first, then choose the treatment that matches it.
If Mould Keeps Returning, Look Beyond the Heat
Recurring mould usually points to a moisture problem that heat alone cannot solve. The important next step is finding out why that surface keeps becoming damp.
Condensation may be involved, but so can water ingress, poor insulation, inadequate extraction or a cold bridge. Treating the visible patch without understanding the cause often means the same problem returns.
A proper diagnosis gives you a clearer route forward and helps avoid spending money on the wrong fix.
Weather Wise Solutions offers free damp and energy efficiency surveys across its service areas. The survey can help identify what is driving the moisture so the treatment matches the actual problem rather than the symptom.
FAQs
At what temperature does mould die?
There is no single temperature that kills every type of mould. Around 60°C can inactivate some fungal structures under controlled conditions, but the result depends on the species, spore type, exposure time, moisture level, and the material being treated. Some heat-resistant spores can survive higher temperatures, so 60°C should not be treated as a guaranteed household mould-killing point.
Will turning the heating up kill mould?
No. Normal central heating temperatures are far too low to act as mould remediation. Raising the thermostat may still help reduce condensation by keeping walls and other surfaces warmer, but it will not remove mould that is already present. Excess moisture still needs to be controlled through ventilation, extraction, dehumidification, or repair depending on the cause.
Does a dehumidifier kill mould?
No. A dehumidifier does not kill existing mould. It removes water from the indoor air, which can make conditions less favourable for future growth when high humidity is part of the problem. The CDC recommends keeping indoor humidity no higher than 50% where practical, although cold surfaces can still develop localised moisture problems even when the room reading looks acceptable.
Can dead mould still cause health problems?
Yes. Dead mould is not necessarily harmless. The EPA notes that dead mould can still trigger allergic reactions, which is one reason contamination should be physically removed rather than simply killed. Even when mould is no longer viable, spores and fungal fragments can remain on the affected surface or inside porous materials.
Does heat kill black mould?
High enough controlled heat can damage or inactivate fungal structures, including mould that appears black, but ordinary household heating will not remediate it. The colour of mould does not mean it needs a special DIY heat treatment. The priority is still to identify the moisture source, remove the contamination appropriately, and stop the affected material from becoming damp again.
Will mould come back after being heated?
Yes, it can return if moisture is still available. Mould spores are naturally present in indoor and outdoor air, so trying to sterilise a home is neither realistic nor necessary. What matters is preventing those spores from finding damp conditions where they can grow. Keeping affected materials dry is therefore more important than trying to eliminate every spore with heat.
Does a hair dryer kill mould?
A hair dryer may heat a very small surface area, but it cannot provide reliable temperature, exposure time, or penetration through materials such as plasterboard or timber. It also does not remove spores, fragments, allergens, or staining left behind. Directing fast moving air at visible mould can disturb contamination, so a hair dryer should not be used as a mould remediation method.