Bathroom Ventilation / Mould / Dampness

[browneye23]

I live in a semi detached bungalow and have a problem with my bathroom ventilation.
After showering or having a bath the tiles are so wet I spend 20minutes plus drying down all the tiles.
The whole bathroom is tiled with a plastered ceiling, with a small radiator.
I have a 6” ceiling fan fitted on a 7m PVC ducting run out my fascia on the timer with the light so it’s on when I shower.
The fan is definitely adequate as knowing my problems I selected a fan which could do twice the job that is necessary for my size bathroom.
In the summer it isn’t bad at all as I can open the window and the warm air dries the tiles very quickly.
In the winter I open the window and the tiles don’t dry (obviously it is not possible to leave them open all the time when it’s freezing!)
I have small patches of mould on the ceiling which I stay on top of by bleaching them every few weeks.
Does anyone have any suggestions on what could be causing my bathroom to remain so wet and damp?

Thanks Paul

 

[Maxsys]

The fan will work best when it has something to move, so leaving the door open, or the window when showering should help, how long does the fan run on for after the shower has been used? and have you checked the vent pipe to make sure it's not full of fluff and dust?

 

[browneye23]

The fan is newly installed so the duct is definitely clear.
Its an adjustable timer up to 30 minutes, currently its about 15 minutes run time after the light goes off.
So should I have window on its latch slightly open when showering? Or won't I be creating more steam\condensation when the hot and cold air meet each other?

 

[Maxsys]

OK this may seem like a dumb question, but is the fan the right way round, i mean it is sucking and not pushing?

 

[browneye23]

Yeah most definitely the correct way up! If it was the wrong way I wouldn't be able to adjust the timer. I can feel it sucking also. Its clearing the steam just not drying the wet tiles after the shower

 

[^woody^]

As the whole room is tiled, there is no plaster for the moisture to soak into so it all just condenses on the tiles - its normal

A fan wont deal with all of this, so the best thing is to get a rubber squeegy or sponge and wipe as much as possible off the tiles

Any condensation will only evaporate later when he fan timer goes off

Also check the loft above the ceiling to make sure that there is insulation above where the mould patch is

 

[browneye23]

So in effect the only way to stop such wetness in the bathroom would be to redesign it by getting rid of the tiles?

Its a huge effort keeping the bathroom dry after a bath / shower and becomes very tiresome through the winter months.

 

[^woody^]

The moisture will always be present. The fan will only deal with some of it, the rest will settle on surfaces, which in turn well either absorb it or show it a condensation - as the tiles are doing.

 

[browneye23]

So basically its a problem can't be solved regardless of what I do in the bathroom?

I have never had this problem in previous places I have lived!

 

[XtraRaptor]

Condensation forms on colder surfaces, so are your tiled walls external?
Have you got cavity wall insulation?
Do you keep the bathroom warm?

 

[browneye23]

The bathroom is fully tiled, one of the walls is external three are not.
I have cavity wall insulation and a fully insulated loft.
The bathroom is heated prior to showering every morning, it is worse if it isnt.
I am sure if I heated all the tiles prior to showering it wouldnt be as bad - obviously this isnt practical!!

 

[^woody^]

The bathroom is heated prior to showering every morning, it is worse if it isnt.
I am sure if I heated all the tiles prior to showering it wouldnt be as bad - obviously this isnt practical!!

It makes no difference

The shower/bath will produce the same amount of water which will be evaporated into the same volume of air, and the fan will extract the same amount of air.

So the moisture has to be somewhere - either on the tiles, soaked into permeable materials or just hanging around as humidity.

The fact that this did not happen in a completely different property with a completely different set of circumstances, does not come into it

Air will condense on any surface where the dew point is reached, and then will not evaporate off until temperature and air movement change.

The only way to stop this is to heat up the bathroom to a temperature of something like 20-25 degC, which will cause the moisture to evaporate, and then keep the heater and fan running until all the damp air has been extracted. In practical terms this will take a long time

Or fit a bigger, better fan

 

[browneye23]

I need some heated tiles!

I already have a 6“ fan which extracts twice the capacity that the bathroom needs!

So it looks as I thought there isn't really an easy solution.

 

[Deluks]

Ideally the fan should be as far away from the air 'inlet' as possible. So if your window is right next to the fan then you will only create air movement in a very small area. Leave the door slightly ajar or fit a vent in it at the bottom.

 

[STEVEROG]

Some points (many have already been covered but...)

1. Heat

As already mentioned, extraction alone is pointless, the room must be kept warm. Ensure you have sufficient heating otherwise all bets are off.

2. Insulate

You need to keep the heat in, but more importantly you want to try to keep those tiles warm. Ensuring you have insulation the other side of the tiles (where appropriate) is important.

3. Extract

This is the one that is the hardest to get right. Some of this has been covered but not in anywhere near enough depth. First off, to get this right you need to ensure that your extraction point and it associated air inlet point are sited well. I would opt to put the extract above the shower cubicle and then the inlet point at the opposite side of the room and low down to ensure that the air is pulled across the room and in effect it will then clear more of the room. The classic error you often see is the extract near to a window or other air inlet point that ends up shorting out the air path.

Next, get fan sized correctly etc. If you go the TLC direct web-site they have free on-line calculators so you can correctly size the fan AND take into consideration the size and lenthts of any ducting. Ideally you want round ducting, keeping the duct runs as short as possible. Use a in-line fan, something like an ACM100T from screwfix is a good fan for many bathrooms. Its worth noting that the air extraction rates you need to achieve to meet building regualtions are totally inadequate to ensure you dont end up shaving in steamy mirror with the aroma of the last occupants toilet visit!

A timed fan is a must and better still one with a humidistat, this will ensure that the fan runs till the humidity level is sensible.

Finally, make sure the extract ducting is fitted correctly which means if it's in a cold space you must insulate it. In additon you want to make sure the ducts have a slight slope on the outlet side of the fan and keep the fan close to the extract point to ensure that the fan is pulling warm air and any condensed moisture on the inner of the duct can then run down the sloped duct and out. Of course depending on your extact design constraints you may want to but a condensation trap in etc