The best time to check for mould in a rental is before you sign the lease, not after you’ve moved your furniture in and started noticing a smell.
A short, deliberate pre move in mould checklist during the inspection takes ten minutes and can save months of dealing with a problem that was already there before you moved in. Most of it comes down to knowing what to look for beyond the obvious black spots on a wall.
Look Beyond the Obvious Black Spots
Most rental inspections happen quickly, and it’s easy to scan for obvious black spotting and move on if none is visible. But early-stage mould and the conditions that produce it are often more subtle: a faint musty smell in a bathroom or laundry, slightly peeling paint near a window frame, or a patch of wall that feels cooler or slightly damp to the touch compared to the rest of the room.
Check the Ventilation, Not Just the Walls
A property with no visible mould on inspection day can still be a high-risk property if the ventilation is poor. Look at whether the bathroom has a working exhaust fan vented to the outside, rather than into the roof cavity, and whether windows in bathrooms, laundries, and bedrooms actually open. As covered in Winter Bathroom Ventilation: Why Your Exhaust Fan is Failing, a fan that runs but doesn’t actually extract moist air is one of the most common, least visible causes of mould in otherwise clean-looking rentals.
Ask About the Property’s History, Directly
It’s a reasonable question to ask a property manager or agent whether mould has been an issue in the property before, and how any past incident was resolved. A property where mould was simply painted over rather than treated at the source is likely to show signs again, and knowing that history before you move in changes what you should watch for in the first few months.
Know the Difference Between a Leak and a Structural Moisture Problem
Not every damp patch is the same kind of problem, and knowing the difference matters for what you should expect the rental provider to fix. Leak, Rising Damp, or Condensation? walks through how to tell these apart, which is useful both during the inspection and later if you need to describe an issue accurately when reporting it.
Document Everything Before You Move Your Belongings In
Photograph any damp patches, discolouration, or musty-smelling areas as part of your condition report, even minor ones, before you move any furniture or boxes in. This protects you at both ends of the tenancy — it establishes what existed before you arrived, and it gives you a baseline to compare against if anything develops later. If anything about the property’s moisture history is unclear, testing the air and surfaces before signing can settle the question with data rather than a guess.
Conclusion
A ten-minute check during inspection — smell, ventilation, wall temperature, and a few direct questions — catches most of what a quick walkthrough misses. If something about a property’s condition or history leaves you unsure before signing, a professional inspection gives you a clear answer while you still have the option to walk away.
Related reading: mould in a rental property.
Frequently Asked Questions (FAQs)
What should I check for mould during a rental inspection?
Check for musty smells, peeling paint near windows, cool or damp-feeling wall patches, and whether bathroom exhaust fans actually vent outside rather than into the roof cavity. Visible black spotting is only one part of the picture.
Can I ask a landlord if a property has had mould problems before?
Yes. It’s a reasonable question to ask during an inspection or application, and the answer can tell you whether any past issue was properly treated or simply painted over.
Should I get a mould inspection before signing a lease?
If anything during the inspection raises doubt — a smell, a damp patch, or an unclear history — a professional inspection before signing gives you clarity while you still have the option to choose a different property.
Why does documenting a property’s condition before moving in matter for mould?
A dated, photographed condition report establishes what existed before you moved in, which protects you if a dispute arises later about whether mould was pre-existing or tenant-caused.