Bathroom condensation/mould

Lennylegs · 30 November 2006 at 11:30AM

Hi,

I'm hoping someone can help. We have a flat with a bathroom that is internal (no windows) It's about 1.75 metres wide by about 2.5 metres long. At present we only have a pull cord fan heater but are planning on gutting the bathroom and having a heated towel rail too but we will also have more tiles on the wall. At the moment we have a ceiling mounted air vent that comes on when the light does but asides clearing the air a bit it doesnt seem to do a lot. There are two of us taking showers every morning and the steam either stays in the bathroom and moulds (mould is between all the tiles, shower curtain gets replaced every three months, bath is now starting to collect mould) or if we leave the door open it gathers on our bedroom wall.
I figure with the towel heater that will help. Getting a concealed cistern toilet will also help stop that gathering condensation. On the negative side tiles must be cooler so the walls i guess will be worse ? Does anyone know of some sort of ventilation that will be better than the bog standard flimpsey thing sat on my ceiling now ? My dad has suggested that it could help if we put a grill type thing at the bottom of our bathroom door as the fan needs fresh air to pull it through ?

If anyone has had exp of this or knows far better than me what theyre talking about id be ever so grateful - we dont want to pay for all the bathroom to be done to find it ruined in a couple of years time !

Thanks

Leonie x

BobProperty · 30 November 2006 at 2:04PM

How old is the fan? I suspect it could be dirty, partially blocked or obscured and /or isn't big enough for the job anyway. I think the regulations may have changed in the last few years as to the minimum specification of a fan suitable for a bathroom, so what was considered OK when installed years back might not be up to current standards. I'll post again when I've looked it up.
I think the answer may be a better fan.

webrits · 30 November 2006 at 2:19PM

Looks like the minimum capacity of an extractor should be 54 cubic metres / hour (15 l/sec)
Here a link to a manufacturers giving some info http://www.vent-axia.com/awwebstore/bathroom-exhaust-fans-installation.html
Not sure if this is to comply with 'new builds' only though.

Good luck

alanobrien · 30 November 2006 at 2:38PM

You can get an extractor fan that is triggered by humidity level but that may stay on all the time if the ventilation problem is bad.

A better option may be to replace the fan with a timed one and just increase the time it runs for after the light goes off. Time running after light switch off can typically be varied from a few minutes to an hour.

The first thing to do though is to check the ducting and vent exhaust is clear. Some exhaust (exit) panels are spring loaded and sometimes get stuck shut - ours did in our shower room, took me a while to figure that one out

BobProperty · 30 November 2006 at 2:42PM

Building Regulations Part F (:mad: - my brain hurts)

Anyway - as webrits says 15l/sec but the rules say 15 minute overrun which I don't think the OP has.
Your dad's suggestion is also taken into consideration in the latest revision. I quote:
"Air transfer between rooms
l To ensure good transfer of air throughout the dwelling, there should be an undercut of minimum area
7,600 mm2 in all internal doors above the floor finish (equivalent to an undercut of 10 mm for a standard
760 mm width door)."

Wonder how that will fit in with the fire regs?

ollyk · 30 November 2006 at 3:19PM

I assume the fan is attached by ducting to the outside vent - if this ducting is flexible, not supported very well and in a cold area like a roofspace it is quite likely to have filled with water - effectively blocking the only exit for the vapor saturated air - check it out if you can - put some bog paper over the fan and see if it is pulling air through although it will be best to find all the ducting if possible!

BobProperty · 30 November 2006 at 4:26PM

Ducting is supposed to be insulated if necessary, so again, if older or not to current standards that could be adding to the problem, as per ollyk's post.

Lennylegs · 30 November 2006 at 6:01PM

Hi, Thanks 4 the replies.

I'd say the fanr runs on for about 2 minutes after the light is switched off. The ducting is about 3 metres long max. and goes straight to the outside. As you look into my kitchen and the top end of it there is what looks like a beam running along the ceiling to the outside, that is where the ducting is housed so i guess its fairly well supported. The fan is def. not dirty but i'll put some toilet paper over it to see if its pulling anything at all. Do I just remove the cover off the outside wall to try and see if its clear then ?

The fan isnt that old but i don't reckon an adequate one was put in anyway (year old maybe ? to replace the last fan which really had kicked the bucket!)

Is changing the ducting (if not insulated) a difficult job ?

Thanks

Leonie

Mikeyorks · 1 December 2006 at 12:22AM

You've got between 12 / 13 cu metres of bathroom to vent. You need to change the air 10 times / hour in the circumstances you describe - so you need a fan capable of extracting 130 cu mtrs / hour. And it should be positioned over the shower for best effect (ie get rid of the steam 'in flight' before it has a chance to condense, as the mould damage is being done then.)

Most of the stuff sold off the shelf at B&Q etc is pathetically underpowered. The best ones are the high pressure in-line fans such as these :-

http://www.tlc-direct.co.uk/Main_Index/Ventilation_Index/4_Inch_Fans_Duct/index.html

.... but it sounds as though you have to mount yours on the ceiling as there won't be space to mount / wire an in-line fan within the duct? Which is a shame as the high power ones virtually suck the suds off you, and would solve your problem. And they're quiet, as the motor is normally mounted above the ceiling etc.

If ceiling mounted is the only option - have a look at this - which fits onto 4" ducting and is close to the extract rate you need. There's a 260 cu mtr / hour version if you want to install hand grips to prevent being sucked out??

http://www.tlc-direct.co.uk/Products/ADICON30.html

Lennylegs · 1 February 2007 at 12:48PM

Hi

I know i asked these questions a while ago but we are just getting round to doing it now. We are going to get (as reccomended) the 260 cu/mtr one :

If ceiling mounted is the only option - have a look at this - which fits onto 4" ducting and is close to the extract rate you need. There's a 260 cu mtr / hour version if you want to install hand grips to prevent being sucked out??

http://www.tlc-direct.co.uk/Products/ADICON30.html

However:

The fan comes on with the light pull, and at night time i so wouldnt want this fan coming on, also, our fan only runs for 2mins and i think this needs to be increased (5mins??). We have another pull cord that is for the shower, could an electrician change the wiring so that when the light pull is pulled only the light comes on and when the shower cord is pulled, the shower and the fan come on ?

We dont want one that detects movement because of the cats. I dont want it to keep coming on so that rules out the humidity one.

Any thoughts ?

Thanks

Leonie

navig8r · 2 February 2007 at 9:32AM

Have you enough fresh air entering the building?? a fan can only extract X cu mtrs of air from a building if X cu mtrs can enter the building to replace it .

Dave

Bathroom condensation/mould

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