Tips to Finding a Mould-Friendly Rental Without Water Damage When You Have CIRS/Mould Sensitivity
Finding a new rental home should be exciting, but if you have CIRS, and you’ve already been through one (or more) mould nightmares, then it can feel extremely overwhelming.
The list isn’t fool proof, (nothing ever is!) but in this post, I’ll walk you through a step-by-step approach to help you find a healthy rental home, from researching the area to checking for hidden water damage and mould, to asking nosey questions to the real estate agent.
But first, I’ll tell you what we’re NOT going to do.
And that’s walk into a home, see no mould, and sign a lease. That’s a bad idea, and likely to end in tears.
Unfortunately, mould and water damage is too common to be able to take a gamble and hope you’ll get lucky. That might work if it were only 10% of rentals that had issues, but the number is much higher. In fact, the issue is rampant, and the general public do not understand the risks of living in a mouldy environment. Most mould-conscious people can expect to look at a fair few rentals before finding one that suits.
1. Start by Researching the Area
Most people underestimate the usefulness of doing this, but Google is your friend here. I do this before every home inspection. It’s important to understand the area where you’re looking to rent:
• Flood Zones: Check if the area is prone to flooding. Flood-prone areas are more likely to have recurring water damaged homes.
• Weather History: Research extreme weather events. Has the area experienced heavy storms or flooding in the past? If the area has a history of these events, it may be more susceptible to water damage. Typing in google something like “Suburb name - heavy thunder storms flood” can sometimes give you all the info you need. You can look at what streets have been affected and so on, or read about if the river nearby regularly bursts its banks.
• Health Risks: Consider proximity to bodies of water. Some lakes or ponds will have harmful cyanobacteria (blue-green algae) blooms. The bacteria produce biotoxins, and can trigger CIRS in susceptible individuals (particularly those with a multi-susceptible HLA).
2. Learn the Signs of Water Damage
Before inspecting a rental property, it’s essential to familiarise yourself with the signs of water damage. If you have CIRS, it’s generally just important to familiarise yourself with these. Learn them once, learn them forever!
While mould might not be visible during an initial walk-through, water damage might be - and it’s a major indicator that mould could be hidden behind. Here’s a quick guide on what to look for:
• Stains or Discoloration: Yellow, brown, or dark water stains on walls and ceilings are a classic sign of water damage. Especially the tea-coloured stains on ceilings.
• Peeling Paint or Wallpaper: Bubbling paint or peeling wallpaper often indicates moisture behind the surface, which can lead to mould growth. Don’t ignore this thinking it’s just a maintenance issue.
• Warped Floors: When wood or laminate floors absorb moisture, they swell and become uneven, and can flip upwards or downwards. They’ll stand out as not being smooth/flat. Sometimes with vinyl flooring, there’s just issues with the glue that’s meant to be holding it to the floor - so use your best judgement to gauge how iffy it looks (or ask the real estate agent about it). If there’s clear water staining (like the second pic here), in addition to the swelling - it’s water damage for sure.
Swollen Skirting Boards: If skirting boards (called baseboards in the US) appear swollen, this is a big red flag and indicates water has been seeping into/out of the walls. Swollen skirting boards = CIRS enemy #1.
Wait, scrap that, CIRS enemy #1 is mushrooms growing inside the house. If you see that, ANYWHERE, and I mean literally anywhere - RUN. You cannot even imagine how waterlogged a wall has to be support a growing mushroom family.
Check out my Instagram post below - there are loads of these types of pictures/indicators. Save it, and look through it before the inspection once again.
There are quite a lot, and it’s not to memorise, but to get familiar with what problem areas can look like. The most important thing for people to understand is that we are not looking for mould. MOULD HIDES. We are looking for signs of WATER DAMAGE, because where there is water damage, there will be MOULD.
Instagram Post: Signs of Water Damage - Click here.
3. Before you visit the rental, screen the real estate ad so that you don’t waste your time
Before you go, screen the real estate ad for any of the signs above. Potentially rule out or be wary of homes that are at the bottom of a hill, bottom of a valley, or down a steep drive way – water is always running down towards those and many don’t have good enough drainage. Flat land (or even better, land sloping away from the home) is ideal.
Flat roofs also tend to have a bad reputation. They don’t shed water as easily as a pitched roof and therefore are prone to waterproofing membrane issues. A new flat roofed home/apartment will be less risky than a 30 year old place with a flat roof. A pitched roof with large overhangs/eaves is the preference. Think of the phrase “a house should always have a good hat”. This is also very important if you’re looking at a top floor apartment - the roof will need to be in extremely good condition.
This roof is lower risk than the flat roof below.
Don’t go for homes that are really dark/really shady/really cold. Buildings need lots of sun to keep them free of dampness.
4. Use your sensitivity to test the home
If you have recovered at least a little bit from CIRS - you can likely use your mould sensitivity to “feel” which places are very bad, and strike those ones out. Unless you’re a delayed reactor - that can be more tricky.
If I feel fine, and then walk inside a building and suddenly feel brain fog, a flat mood, am yawning a lot - I know there’s a mould problem there and I’m having an immune response. I wouldn’t rely on my sensitivity alone to test a home if I had the option to test scientifically, but would use it to screen for the really bad ones without wasting more time on them or going forward with spending money on testing.
And obviously, be smart about this - don’t stop off at your favourite water damaged shopping mall or coffee shop on the way over. Make sure you’re feeling clear and well so that you can test properly.
5. Take a VCS test
If you have CIRS and know that you can now pass a Visual Contrast Sensitivity test, you might try taking one before the rental viewing (use www.VCSTest.com or https://www.survivingmold.com/store/online-vcs-screening) and then taking another VCS test around 4-6 hours after the viewing. (Make sure you don’t go off visiting other buildings in this time so that you’re controlling for all variables)
6. Before you go inside, have a big sniff of the outdoor air.
Think carefully about the smell outside versus the smell inside. Can you smell mould/mustiness/damp carpets? A home should smell like fresh air and not much else. If there’s a hallway in an apartment block, include this in your sniff test as you walk in. Do extra sniffing under sink cupboards, in wardrobes and in bathrooms and laundries.
7. Be aware of new paint smell.
This might be normal, and the place has just generally been done up, but sometimes it can be a red flag for a mould cover up - especially if it’s just in one or two areas. The same goes for air fresheners or candles everywhere - the home should smell fresh WITHOUT all of that.
8. Head inside for the inspection
Look around for the signs of water damage that you’ve now familiarised yourself with.
And obviously - look for visible mould. Depending on where it is, if mould is visible, it may signal there is more hiding behind the surface.
9. Check Under Sink Cupboards for Leaks
Water leaks are often hidden in inconvenient places—like under the sink. Be sure to open every cupboard beneath every sinks (kitchen, bathroom, laundry) and check for:
• Signs of Staining or Leaks: Water stains/bubbling/damp patches on the wood/MDF board are red flags that water has been leaking in the area. Check for musty odours. If you can smell mould, there’s mould.
Whilst you’re under there, make note of any braided flexi-hoses that are rusted, as if you move in you’ll need to let the landlord know that they’re due to be replaced because they’re at risk of bursting. These things can flood a home in record time (they account for 22% of all water damage insurance claims in Australia - bring back the copper pipes!).
10. Inspect the Bathrooms Thoroughly
Bathrooms are particularly prone to water damage due to failed waterproofing systems and high humidity levels when ventilation is poor.
• Check for Stains and Mould: Look for any signs of staining around the toilet, sink, and bathtub. This could indicate that water has been escaping from the plumbing or there are issues with the waterproofing membrane.
• Examine Grout: Cracked/heavily discoloured/poorly maintained grout will allow water to seep through and is a common culprit for mould growth behind tiles. Some mould in showers is normal - for sure. It’s a wet area and without being super vigilant with ventilation and exhaust fans, most shower grout and silicone will have some mould. As someone with CIRS, I don’t find this usually actually bothers me that much symptoms-wise (though if you move in, you can have someone on AirTasker re-grout the shower for you for a couple of hundred dollars if you like).
However, if I am seeing a shower that is full blown black with mould - that’s different. That’s not casual anymore. What that tells me is that there is probably a load of mould growing behind the shower, inside the wall cavity - because the waterproofing has failed. You know those kinds of showers where people scrub mould out of them til the cows come home but then it just reappears a few days later? And then a few days later after that? That’s usually because there’s an undefeatable colony of mould living behind the shower.
• Failed Waterproofing: Bathrooms may have failed waterproofing systems, as just mentioned, which can lead to mould issues behind walls. If the bathroom looks very old and very poorly maintained, you could almost assume there will be some sort of issue. These kinds of bathroom issues tend to mean large amounts of mould are in the air, and if shower waterproofing fails for example, it will be growing all through the wall and/or floor cavity and affecting the air in the bathroom plus the adjacent rooms. No good.
11. Look for Condensation and Mould Around Window Sills
Window condensation is pretty common and will cause mould in the window sills if there’s enough dust sitting in there for mould to grow on. Mould can’t grow on an aluminium frame, as it’s non-porous, but will grow on the dust/grime/grease sitting there (when humidity is high enough).
I probably wouldn’t rule out a home for this infringement alone (since you’ll be using dehumidifiers/managing humidity levels/keeping the sills clean), but there’s a limit to what’s tolerable. Is it a bit of condensation related mould or is there LOADS of it, signalling a potential larger moisture issue around the window like a leak. Or can you actively see condensation related issues like water running down walls/windows?
If so, that signals a building that’s not “breathing” properly and has very high internal humidity levels. Very high humidity levels can also be related to waterlogged building materials/leaks.
If you have a little hygrometer at home already (~$15 on Amazon -https://www.amazon.com.au/ThermoPro-TP357-Hygrometer-Thermometer-Temperature/dp/B08LKCLFR6?ref_=ast_sto_dp), you could potentially set this down in a few areas and check the humidity levels (it takes a moment to calibrate).
When I inspect homes, I take relative humidity (and a few other types of) readings in each room of the house, and compare them to each other as well as to the outdoor level.
So check the humidity level outside just before you go in, if its 50%RH, but everywhere inside the rental is 70%RH - there’s issues. The humidity being a bit higher indoors is normal - since people are washing/cooking/bathing/breathing and might not be ventilating properly. But more than 10% higher would start to raise alarm bells for me. If everywhere you check is say 50%RH, but the master bedroom is 70%RH - that’s a big red flag that there’s an issue in there (provided someone hasn’t just taken a shower in the en suite).
12. Check Behind Curtains for Hidden Mould
Don’t forget to check behind curtains, especially curtains near windows or glass doors. Curtains that have been exposed to constant condensation often harbour visible mould on the back. I wouldn’t rule out a rental over this, but if we’re looking for clues about the home, this is one. You’d have to be prepared to take the curtains down if you wanted to stay and they had mould - opening curtains with mould on them will disperse THOUSANDS of spores (usually Asp/Pen-like) into the air. The home (or at the very least the affected area) would also need to be deep cleaned.
13. Look for Peeling Paint or Wallpaper on the Walls
Peeling or bubbling paint is often an indicator of water damage. I used to just think this was paint needing maintenance or a patch up job - but it’s generally not, it’s caused by water pushing the paint off the surface. A wall that has bubbled paint or peeling wallpaper is likely hiding significant water damage behind it.
14. Check the Exterior for Maintenance Issues
The outside of the property can reveal a lot about the condition of the home. Get there early and use your time to look around the outside of the home first before anyone arrives. If you happen to see any other people who live there/next door - ask them about if there’s been any issues! You’ll be surprised by how happy people usually are to gossip about this kind of thing.
• Clogged Gutters: Overfilled gutters can cause water to overflow backwards into the roof cavity, potentially leading to mould in the ceiling. If the gutters are absolutely chockers with leaves, this is a red flag for roof cavity issues. If they can be cleared out, and the rest of the home passes your visual inspection - this might be okay. But if the gutters are clogged, and the whole home looks poorly maintained, this is a problem and suggests they may have been clogged for A LONG TIME.
• Poor Drainage: Check if water is pooling around the foundation of the house. The land should slope away from the property to prevent water from seeping into the foundation or lower levels. Check the neighbouring property isn’t draining right into the rental property by way of it’s slope.
Ensure downpipes are properly directed to drains—if not, huge amount of water will be being dumped right at the base of the home every time it rains.
• Building Stains: Does the exterior of the building have rust or water stains? Are there plants growing out of the side of the building? (Plants need lots of water to grow).
Is there green moss and lichen on the building? (Moss needs lots of water to grow, so it’s telling you an area is wet if you see it).
Is the grass dead in certain patches because of pooling water? This suggests poor drainage.
15. Gold standard rental screening - Use ERMI or HERTSMI-2 Test to Check for Mould
If you’re really serious about testing a property, an ERMI (Environmental Relative Mouldiness Index) dust test is one of the most accurate methods for identifying mould contamination. Basically, you take a swiffer cloth (looks like a white microfibre cloth), run it along a bunch of surfaces in the home, and send it off to the lab for DNA analysis of what’s in the dust. It’ll tell you what kinds of moulds are there and in what amount, including an overall “mouldiness” score. If you don’t know what this test is and want more info, search here: https://www.mouldwise.com.au/articles/ermi. The downside is it doesn’t tell you where the mould is/how to fix it etc, you would need a mould inspector for that.
And the test is very costly ($470 through NSJEnviro.com.au).
There is a cheaper version of this test called the HERTSMI-2 (~$250). It’s the same ERMI technology, but tests for only the 5 most toxic mould types that Dr Richie Shoemaker has determined cause the most trouble for CIRS patients. ERMI tests for 36 species.
HERTSMI-2 can be found here - https://www.envirobiomics.com/product/hertsmi-2/ (US company) or https://mouldtests.com.au/product/mould-testing-kit-test-5-moulds-via-hertsmi-2-analysis/ (Australian company). NSJEnviro no longer offers HERTSMI-2, only ERMI. The HERTSMI-2 test will give you a score and tell you if, based on the dust sample, the house will be safe for someone with CIRS. It looks like this:
You wouldn’t do either of these tests until you’ve already done all the checks you can - checking the area for flooding, looking for water damage red flags, using your senses etc. It’s too expensive to test them all on a whim. And we can easily strike out a number of them just through a visual inspection.
Here’s what you can do:
If the house checks all of your boxes, do an inspection and use an ERMI Swiffer cloth to subtly take samples around the home (https://nsjenviro.com.au/product/ermi-analysis-swiffer-sampling-kit/ ). Try to avoid being seen so that you don’t look like a pain in the butt tenant (often one person will distract the agent by chatting to them while the other person swipes). The cloth itself is worth $8-$10 (https://nsjenviro.com.au/shop/) (you can buy 3/5/10 pack), it’s the processing of the sample that costs money ($470). So you only process the ones that you’re really keen on/that are available/that have passed all of your other checks.
Turn-around time with NSJEnviro is usually 5-7 business days (much quicker than the previous 2 weeks) (but call and check with them). When you need, read the article I wrote to ensure that you’re sampling in the right places etc. HERE: https://www.mouldwise.com.au/articles/ermi.
Pending the state of the rental market and how competitive things are, sometimes 5-7 days waiting for results will be too long and just won’t be practical.
16. Consider Air Conditioning Systems
Air conditioning units can harbour mould if not properly maintained. In fact, they’re NOTORIOUS for it.
It's easier if the air con is a wall hung split system unit rather than a whole home ducted system. If the split system is mouldy, it will need to be professionally cleaned when you move in (if you can, its much better to hire Sanitair or another company that will bag and pressure wash it - not someone the landlord sends in who will just wipe it over and pretend the mould is gone).
Dirty/black vents on a ducted air con system tell you there’s likely to be mould in there - and its harder to get out because the ducts would need replacing (or you’d have to commit to not using the system when you live there and sealing it off).
You could ask when the air con was last serviced and who covers the cost of that. Note that if it’s you, split systems and ducted need to be serviced 2x year and its a few hundred dollars each time.
17. Be exceptionally wary of subfloors (crawl spaces in the USA)
The crawlspace (often referred to as the subfloor in Australia), is the area under the home that you could get on your knees and crawl around in the dirt (unless the house is on a concrete slab then there won’t be one). They’re kind of like little caverns under the house, usually full of spiders etc etc.
Subfloors with mould in them will mean houses with mouldy air in them. This is because warm air rises and whatever is in the subfloor will travel upwards through little cracks in the floor boards, walls and so on. A damp subfloor is a big no. If you see one of these, and there’s puddles or water or it smells damp, it will be a problem. Or a subfloor that clearly has no drainage around it and the land slopes towards the house - it will be soaked every time it rains. Soil + water = mould.
Basements can come with the same kind of issues in the USA - it’s about being mindful that the air will rise up [[unless in the rare case that there is a special ventilation system in there and it’s being positively pressurised outwards]].
Try to have a quick glimpse under there (and hold your breath as you do!).
18. Other Useful Tips (just when you thought you were done)
Take a torch with you and shine it perpendicularly down any suspicious walls or areas. You will be AMAZED by what just a simple torch at the right angle will cause to show up.
If you can get a house/unit without carpet, or minimal carpet, thats ideal (though rare). Carpet with clear water staining is also a red flag.
You can also purchase a cheap moisture meter from Bunnings (https://www.bunnings.com.au/crommelin-moisture-meter_p0911078?srsltid=AfmBOopHREYp23YW7ZJ8Hz6bVASWFb4ItJaYKyHmHK0BEFiF-ZGhKC_k) and check areas that look suspicious (ie bubbling paint or stained areas). The rear side of a shower is a great place to check. But be mindful that moisture meters are usually used by people trained to use them and can sometimes end up causing more confusion (ie if something reads wet but really its a false positive from metal) and also if the area is currently dry, it won't show up as a moisture issue but could still have hidden dead mould behind the area.
Some people recommend purchasing a cheap thermal imaging camera. Personally, I don’t love this idea as there’s too much room for confusion when you aren’t trained to use them (ie is the wall wet or is it just missing insulation?) and it is time consuming to fully scan all walls/floors/ceilings of a house in the time that you have for a rental inspection - time that’s probably better spent using your eyeballs.
If it’s a rainy day, that’s an even better time to inspect the house. More of it’s true colours will be revealed.
Go to MORE THAN ONE VIEWING. If there’s two viewings, go to both, see how you feel after each inspection, and look for more red flags each time to ensure you haven’t missed anything.
If the rental market is slow enough to allow for this, and you have the budget for it, consider bringing a mould testing technician in to assess the home.
Consider that depending on your level of sensitivity, you may need to small particle clean the home prior to moving in.
19. Things you could ask the landlord to snoop for extra details
Let the real estate agency know that you have a severe mould allergy (don’t say CIRS or start talking about toxic mould illness - you'll end up looking like you’re going to be a pain in the butt tenant as most people have no idea that mould can cause illness beyond coughing and asthma). Use this as an opening to ask about any previous water damage/flooding/water events/leaks/sink overflows etc. Say that its important to you because you’ll feel sick moving in if theres any.
Ask about the rental history. If the property has been rented and then vacated frequently, it might be a sign that the tenants don’t like staying. It tends to be the same with homes - those that are sold every couple of years are usually sold for a good reason.
Remember to ask about when the air con was cleaned last/who pays to maintain it.
18. What To Do If You Can’t Test Before Moving In
If you have no choice but to move in without testing (which is very common), here’s what you may be able to do to protect yourself. None of these are perfect suggestions and I wish I had more of them - or something that was foolproof. What you choose to do will depend on a number of factors like budget/practicality/your individual sensitivity level and so on.
But know that you are FAR better off, now that you know the signs to look for and the questions to ask.
But here are a few ideas:
Move in, but before bringing all your stuff in - deep clean, set up air purifiers and dehumidifiers everywhere that you can for 24 hours so that if you move in and find an issue, your stuff will have been somewhat protected.
or
Move yourself in (without your contents), spend a good 24 hours in the place, sleep the night in there on a cheap blow up bed, and use your body to check how the rental feels. But note that you would need to conduct some type of testing to then prove there is hidden mould to break the lease (and ERMI isn’t usually good enough for this purpose).
or
Move in, protect your contents as much as you can, and have a mould inspector look over it for any signs of water damage or mould so that you can lodge a request to have it fixed ASAP. You could also consult virtually with a mould consultant to look over any areas you have concerns about or to help you test.
I’d love to have a few more recommendations on how best to protect yourself when you can’t test (if you’ve got any, please post them below!). None of this is black and white unfortunately, but I hope that these tips really help you. GOOD HOMES DO EXIST!