How high is too high for internal humidity levels?
I'd like to know about the ideal level/range for the structure & the health of the people living inside.
Hello @Else
In most Australian homes, indoor relative humidity sitting between about 40 and 60 percent is generally considered ideal. That range tends to balance comfort, building durability, and health.
Once indoor humidity regularly rises above 60 percent, you’re moving into territory where problems become more likely. Research from the World Health Organization and CSIRO has linked sustained humidity above 60 percent with increased risk of mould growth and dust mite proliferation. Mould can begin developing on some surfaces when humidity stays above roughly 65 percent, especially in poorly ventilated areas like bathrooms, laundries, and wardrobes. Beyond structural damage such as swelling timbers, peeling paint, and corrosion, mould exposure has been associated with asthma flare-ups and other respiratory symptoms, particularly in children and older adults.
On the other hand, consistently dropping below about 30 to 40 percent can dry out timber flooring and joinery, and may contribute to dry skin, irritated eyes, and respiratory discomfort. Australian studies on housing performance, including work referenced by CSIRO, support maintaining mid-range humidity to protect both materials and occupant wellbeing.
Because Australia’s climate varies widely, homes in tropical and coastal regions may need active moisture management such as good cross-ventilation, exhaust fans, or dehumidification during humid seasons. In cooler southern areas, managing condensation in winter is often the bigger concern.
As a practical guide, if your indoor humidity is regularly sitting above 60 percent for extended periods, it’s worth taking steps to bring it down. Keeping it in the 40 to 60 percent range is a sound target for both the building and the people living in it.
If you need further assistance, please let us know.
Eric
Hi @Else,
I thought I'd just add that Eric’s advice also broadly applies in New Zealand, with an ideal indoor relative humidity range of about 40–60%. However, in many parts of NZ, particularly in cooler, damper regions and older housing with lower insulation levels, condensation and winter dampness tend to be more persistent issues than in much of Australia. Because outdoor temperatures are often lower and homes may be heated less consistently, indoor humidity can more easily condense on cold surfaces, increasing the risk of mould growth even when overall humidity readings don’t seem extreme. As a result, good insulation, adequate heating, and effective ventilation (especially in bathrooms and kitchens) are particularly important in NZ homes to keep moisture under control and maintain that healthy mid-range humidity level. Mitchell
"the health of the people living inside"
Hi @Else
I was just wondering if you have issues in the workplace or government housing?
Thanks Eric & Mitchell. That's really helpful.
Hi Noyade, no issues at work or in govt housing. If I did have issues though, would you have any comments/advice?
Let me tag @Noyade to make them aware of your query.
No, it's all good @Else - I was trying an internet welfare check - to see if you were OK and if we could contact the appropriate administrative body who could help you if humidity was hurting.
Cheers!
👍️
That's very kind, Noyade. Thank you 😊
Given the potential health effects, I hope that anyone reading this/having trouble at work or in govt housing reaches out.
