Advice on best way to stop mould on walls and ceilings in bedrooms

Forums › Home Workshop DIY › Advice on best way to stop mould on walls and ceilings in bedrooms

DanielWilliamsNZ

3 posts

Wannabe Geek

#299351 1-Sep-2022 08:44

Hi, I have an investment property that has issues in the bedrooms with mould on the walls and ceilings. The tenants said that they are ventilating the bedrooms and cleaned down mold regularly but keeps returning. I currently have a heat pump in the lounge and no issues there. I am looking for advice on how to fix this issue? I would like to keep the costs as low as possible but ensure the tenants don't have to put with the mould on an ongoing basis.

I am keen to either get advice here or advice on someone who I can pay to visit the property who can advise on the best solution who is independent - the options I have looked at so far have been tradespeople who specialise in installing a particular product that they have been keen to install given they specialise in that product, but it hasn't been clear that this has been the best option for the issues.

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#2961761 1-Sep-2022 08:46

Heat entire house to 20 degrees C.

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timmmay

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#2961763 1-Sep-2022 08:52

Look for a place that does home assessments. In Wellington the Sustainability Trust does them.

In general I would think:

Good ventilation - positive pressure ventilation for example, pushing air out into each room. It can be on a timer so it's not pushing cold air in at night.
Adequate heating.
Remove moisture at the source

Once mold is there I wonder if you have to do something drastic to get rid of the spores. Best get an assessment done to work it out.

DanielWilliamsNZ

3 posts

Wannabe Geek

#2961781 1-Sep-2022 09:06

Thanks Timmmay for the reply and thanks for the advice on Wellington Sustainability Trust. The property is based in Auckland so I have contacted the Wellington Sustainability Trust to see if they can recommend someone in Auckland who is independent / similar to them.

DanielWilliamsNZ

3 posts

Wannabe Geek

#2961783 1-Sep-2022 09:07

Spyware:

Heat entire house to 20 degrees C.

Thanks for the advice on that.

timmmay

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#2961787 1-Sep-2022 09:22

DanielWilliamsNZ:

Thanks Timmmay for the reply and thanks for the advice on Wellington Sustainability Trust. The property is based in Auckland so I have contacted the Wellington Sustainability Trust to see if they can recommend someone in Auckland who is independent / similar to them.

Try Healthy Homes NZ (found it on Google). They have offices all over the country apparently.

lxsw20

3507 posts

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#2961789 1-Sep-2022 09:32

I've fixed a similar issue in my home by installing a moisture master, repainting the rooms using a mould stop primer and running a dehumidifier in the room once a week.

I've also taken down a bunch of greenarary that was stopping the rooms getting sun during the day.

duckDecoy

867 posts

Ultimate Geek

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#2961790 1-Sep-2022 09:32

If you have mould behind the gib or wallpaper etc you need to get rid of it and treat the source or it will simply keep coming back. For example if your framing has mould it will keep coming through the wallpaper or gib etc.

Gordy7

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#2961791 1-Sep-2022 09:34

Dehumidifier.

No unflued gas heaters being used.

Bathroom door closed and bathroom well ventilated.

Gordy

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mattyb

254 posts

Ultimate Geek

#2961804 1-Sep-2022 09:59

I had a similar issue in a rental in Mt Wellington. Installed one of these systems a few years ago and the issue is gone:

https://www.healthaire.co.nz/

tripper1000

1602 posts

Uber Geek

#2961844 1-Sep-2022 10:58

One of my investment properties starting having this issue after 8 years of no problems (started 12 months after a change of tenants).

Short story: The ultimate solution was an HRV and the tenants are now happy with the situation.

Long story: Property manager advised that a HRV is the norm in rentals now days and it is very rare not to have them. When I installed one I chose one with the most vents and that moved the most air. (Buy once, cry once). HRV's are good because they force good ventilation and have a good reputation so many people accept them. Some tenants resent the perceived power consumption and turn them off, so you might have to hide/lock away the control panel. The Healthy homes standards stipulate a bunch of manditory ventilation rules that the landlord must provide (opening windows, range hoods etc), but the standards fall short and don't mandate that the tenant has to actually use any of those things. HRV are smiled upon by the standards, helping to achieve compliance but unlike the alternatives an HRV is automatic, so they're a win-win - between the landlord and law makers, houses are kept healthy despite tenant actions.

In diagnosing and fixing the problem, you can't rely on the information the tenants give you and you can't tell people to change their habits without causing offence. People say they are ventilating and that they're not filling the place with moister (honestly believing it is so), but this is highly subjective observation and relative to their experiences, expectations and knowledge. For example they might be venting 5 hours a week which is a lot for them but they can be oblivious to the fact that they barely ventilate all all compared to their mums/former partners who vented 8 hours a day, 7 days a week.

My situation in detail - skip if you don't care: The basic problem at my place was new sources of moister and the house being locked up all day. New tenants dried laundry on racks in the lounge where as previous tenants used the outside clothes lines or driers in the garage. New tenants all worked where as the previous tenant was a stay-at-home-mum who was house proud and spent much more time maintaining the place. Old tenants had a baby so kept the house much warmer - new tenants were more conscious of power consumption so didn't use the heat pumps as much.

My tenants did not recognise wet laundry as a source of moister that contributes to mould and the property manager had to get tough and draw their attention to the tenancy agreement prohibiting using drying racks inside the house. (yes you can do it if you do it right, but many don't) Then you get into cooking habits, showering habits, indoor gardening and all the other moisture generating activities that you just can't control/aren't your business.

mudguard

2064 posts

Uber Geek

#2961860 1-Sep-2022 11:32

I still thought HRV systems were just holes in the ceiling with a fan to move the air from the roof space to the room and vice versa? If it's anything like my brother's one it doesn't do anything most of the time, as in summer (Auckland) the roof gets close to 50 degrees during the day, and in winter you might get a narrow window where you want to exchange the air. Otherwise the roof temp gets too cool.

And a bonus is the perpetual brown ring of dust that always gets blown onto the ceiling around it.

They wound up blocking them off and putting multiple heat pumps in.

timmmay

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#2961866 1-Sep-2022 11:55

mudguard:

I still thought HRV systems were just holes in the ceiling with a fan to move the air from the roof space to the room and vice versa? If it's anything like my brother's one it doesn't do anything most of the time, as in summer (Auckland) the roof gets close to 50 degrees during the day, and in winter you might get a narrow window where you want to exchange the air. Otherwise the roof temp gets too cool.

And a bonus is the perpetual brown ring of dust that always gets blown onto the ceiling around it.

They wound up blocking them off and putting multiple heat pumps in.

I modified my system to pull fresh air in from the eaves, via a HEPA and carbon filter. I found the ceiling was too hot in summer, not warm enough to bother with in winter, and old houses have FILTHY ceiling spaces. The sock filter that was on it did nothing. Once I changed the ducting to pull from outside through the filter the whole house smelled better.

We also put in ducted central heating with heat pumps.

Linuxluver

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#2961871 1-Sep-2022 12:10

DanielWilliamsNZ: Hi, I have an investment property that has issues in the bedrooms with mould on the walls and ceilings. The tenants said that they are ventilating the bedrooms and cleaned down mold regularly but keeps returning. I currently have a heat pump in the lounge and no issues there. I am looking for advice on how to fix this issue? I would like to keep the costs as low as possible but ensure the tenants don't have to put with the mould on an ongoing basis. I am keen to either get advice here or advice on someone who I can pay to visit the property who can advise on the best solution who is independent - the options I have looked at so far have been tradespeople who specialise in installing a particular product that they have been keen to install given they specialise in that product, but it hasn't been clear that this has been the best option for the issues.

We installed a home ventilation system. The idea is that it circulates air around to prevent damp and mold. It's not a heating system.

But you still need to have a roof that isn't leaky (moldy ceilings are a symptom) and you can't be drying clothes on a drying rack inside. The moisture from the clothes has to go somewhere. The other thing is keeping the house warm at night. At least 15C. If the heaters are off all night to save power then the walls get 'cold' and moisture from people and showers and whatever condenses on the walls and ceilings and things 'grow'. We cured a mildew problem just by keeping the house at 15C or above overnight.....so you don't get the micro-condensation on surfaces in the morning when humidity rises but the walls are physically cold.

In one case, we reduced the tenant's rent so they would have more cash for heating and it ended up fixing the problem.

BUT!!! Be aware if you get the house assessed for the healthy homes standard...and it fails....you have 90 days to remediate the problem or the tenant can (rightly) take you to the Tenancy Tribunal for mediation and possible compensation if it can't resolved in a timely way.

We currently have a house that has failed...and we can't afford to fix it right now....(improper moisture barriers) so we've told the tenant we can't fix the problem and they are free to move out when they find a new place and we will then sell the house (or just use it ourselves as place to stay). We won't be renting it again. I mention it because it's a risk people need to be aware of.

https://www.smartvent.co.nz/

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mattenz

190 posts

Master Geek

#2961874 1-Sep-2022 12:12

I wish that we could stop calling PPV systems 'HRV'.

Clima

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#2961888 1-Sep-2022 12:55

Cleaning down with white vinegar will certainly retard any regrowth

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