Black Mould in Bathroom (DIY Help Needed)

martinturner · 6 Oct 2009 at 11:53

I replaced the sealant around our bath a month or so ago as it had started to go black. I used some expensive sealent which claims it does not go black. Its a month later and its really black. I went through a period of trying to manage it by pouring bleach along it once a week, whilst it turns the black a light grey, its still very unsightly. Also, our shower curtain needs replacing every few months for the same reason, the bottom foot goes a black mouldy colour. Basically, anything that remains wet in the bathroom seems to develop a case of black mould that I cannot get rid of. What can we do?

The bathroom is part of a kitchen/bathroom extension, whilst the kitchen has a proper sloped/tiled roof unfortuntely the bathroom has a flat roof (looks like black pebbledash material). Also, it does not look insulated, as the bathroom is freezing in the winter time. Other information, there is a fan which goes through bathroom to outside which we use after shower etc. Additionally a radiator in the bathroom.

We plan on replacing the bathroom and putting a new (probably sloped) roof on it, but cannot afford to do so until the middle/end of next year. Basically, how big a problem is the black mould? Its really unsightly, so is there a temporary solution that will work until next year when we plan on sorting it out? Oh, the edge of the bath is not flat so cannot use one of those strip things, hence why I bought/used silicon sealant.

Lastly, anyone got a 'rough' idea about cost for new roof etc? Bathroom is about 8/9ft x 10ft give or take.

Thanks

dannyjo22 · 6 Oct 2009 at 11:56

I leave a window open all the time to air the bathroom. Once the mould has grown it multiplies and the only way to remove it is to reseal the bath. Dry the seal with a towel after each bath. Its the humidity thats causing the growths.

mollymoo · 6 Oct 2009 at 11:57

Black mould is bad for you, or is that green mould, can never remember. If it's your bathroom then you maybe need to look at ventilation rather than anything else. Open a window after your shower/bath, my mother always has her bathroom window open a notch and never gets mould, even leaving the door wide open can help

Burnsy2023 · 6 Oct 2009 at 11:58

Ventilate and use Dettol Mould and Mildew regularly and you won't have an issue

martinturner · 6 Oct 2009 at 12:03

Burnsy2023 said:
Ventilate and use Dettol Mould and Mildew regularly and you won't have an issue

Thanks for all the replies!

So I am taking this to not be a 'structural' problem with my outside walls? No damproofing required? We never open the window after a shower, its mainly because its on the ground floor and the worry is that we will leave it open and someone will try and climb through it. Its one of those tiny windows. Will need to have a think about how to ventilate better then. I am feeling less worried now.

batsy · 6 Oct 2009 at 12:05

You could try one of those shower sprays, i think its called Shower Sparkle.Spray it around after using shower.

MarkDavis · 6 Oct 2009 at 12:13

Sounds like you've got some sort of ventilation problem in your bathroom with that amount / frequency of mould. The key to stopping mould build up is ventilation.

Try leaving a window open or cleaning the extractor fan of dust. You really need to have the fan running if its linked to the light switch even during the daytime when you're using it.

Leaving undiluted bleach soaking on the sealant over night usually works better than the mildew/mould stuff you can buy in the shops.

nin9abadga · 6 Oct 2009 at 12:19

MarkDavis said:
Leaving undiluted bleach soaking on the sealant over night usually works better than the mildew/mould stuff you can buy in the shops.

i agree with this, we've used diluted bleach to get rid of mould on the paintwork/tiles/sealant in both the bathrooms and bedrooms, with a bit of scrubbing it comes off easily. ventilation will be the key, even if it's cold you need to keep the windows open.

re the shower curtain, my mrs found a washable one that was about £3 from wilkos, it's made of more robust stuff then the normal shower curtain and so far (we've had it about 2 months) it's not grown any mould.

Confused · 6 Oct 2009 at 12:20

Almost definitely ventillation (or lack thereof)

Even leaving the window open on the first "latch" (ie it's open a crack but still locked) will help massively, especially if you leave your internal door open too - you'll get some airflow through there - which is what's needed.

martinturner · 6 Oct 2009 at 12:22

The fan we have is not connected to a light. Its a seperate one, we put it on for about 5 mins after a shower, but do agree as its still quite steamy/moist when we switch it off. Will start leaving a window open for longer periods of time. Will replace shower curtain and reseal bath and see how we get on. I was really worried that there was a bigger problem.

Just out of interest, how much electicity do those fans use? Our reluctance for leaving it on is how much power they use. If they do not use a lot, then I guess we will leave it on for much longer (in addition to opening a window). The fan is one that goes straight through the wall to outside.

Thanks for the assistance

pingwing · 6 Oct 2009 at 12:23

Sounds like my old student house last year, you almost certainly have the shower on the outside wall and dont have adequate ventilation on whilst using it. It was so cold last winter that we couldnt use the shower with the window open and just got a massive build up of black mould.

You can use mould killer on it, but proper ventilation is the only solution to the problem

Haze · 6 Oct 2009 at 12:28

yeah im with the others,, my bathroom window is always slightly open 24/7

csmager · 6 Oct 2009 at 12:30

martinturner said:
Just out of interest, how much electicity do those fans use? Our reluctance for leaving it on is how much power they use. If they do not use a lot, then I guess we will leave it on for much longer (in addition to opening a window). The fan is one that goes straight through the wall to outside.

Circa 20W, I'd imagine. Not a lot - it'll cost you a lot more to leave the light on.

VeNT · 6 Oct 2009 at 12:47

csmager said:
Circa 20W, I'd imagine. Not a lot - it'll cost you a lot more to leave the light on.

hardly
most bulbs are 11W or less now?
but still, I feel your pain. we get that but have only one window in our bathroom and it doesn't open just a notch, it a open or closed jobbie.

Rich1988 · 6 Oct 2009 at 12:49

VeNT said:
hardly
most bulbs are 11W or less now?

we have halogen lights in ours and most people tend to have normal bulbs in the bathroom

Indy500 · 6 Oct 2009 at 12:52

Keep your windows open and manually dry the cubicle with a cloth\towel after using the shower. Bathroom extractor fans don't usually push enough air to get rid of the moisture buildup.

csmager · 6 Oct 2009 at 12:54

VeNT said:
hardly
most bulbs are 11W or less now?

Hardly most. Not one of mine is less than 60W. And over half are 100W.

JAMAL · 6 Oct 2009 at 12:56

Burnsy2023 said:
Ventilate and use Dettol Mould and Mildew regularly and you won't have an issue

This, it is brilliant stuff!

Fourstar · 6 Oct 2009 at 13:38

martinturner said:
The fan we have is not connected to a light. Its a seperate one, we put it on for about 5 mins after a shower, but do agree as its still quite steamy/moist when we switch it off. Will start leaving a window open for longer periods of time.

This definitely sounds like a large part of your problem.

Consider installing a humidistat so the fan will remain on until humidity drops to mould safe levels.

As mentioned most fans use in the region of 20W. Put in perspective that would be be 50 hours of continuous running per kWh. I think a kWh costs about 11p at the mo.

RadioheadR6 · 6 Oct 2009 at 14:23

I use Grot Buster - Comes with a handy spout so you can be accurate when blasting the dreaded black mould...

On this subject (and sorry for the minor hijack)... I have a small window next to my shower bath with a roller blind. I have to replace the blind every 6 months or so due to the same black mould issue - Obviously I can't use bleach on this... Any ideas where I can buy a mould proof blind?