Bathroom Ventilation Regulations

[Juju]

I hate the fact that our bathrooms don't have windows. Extractor fans are rubbish in my opinion - nothing beats opening a window for 10 minutes to clear the room of steam and unmentionable smells. Our main bathroom is landlocked but the guest en suite could have a window fitted I guess (in fact there's a bricked up window on that wall but possibly was bricked up cos it is in the middle of the bedroom and bathroom so not very practical) but it would be a lot of work (and I think there's a false wall there hiding pipework). I hate the fact that our main bathroom has drip marks all down the painted walls where the moisture runs down. When the new bathroom is fitted next week, I'll have to think about decorating that room - am really not sure which paint to use (hate the shiny kitchen & bathroom paint) and also whether it would be best to strip off the existing paint... We could get a new extractor fan (I've no idea what spec our existing one is) but would it really make much difference?
Juju

 

[Moo]

Our two shower rooms and our downstairs loo are all without windows and have to rely on extractor fans that come on when the light is switched on, and continue to run for a while (never timed it, I'm afraid) after the light's switched off.
We've always found them satisfactory - no condensation, and no lingering smells.

 

[CatherineB]

Another dumb question - where do all the extractor fans in all these internal windowless rooms vent the air too? If there is no external wall to the room, then they can only vent into the rest of the house, or am I missing something?

 

[Moo]

Our two shower rooms each have an outside wall, within the roof valley, and the downstairs loo's outside wall is both very small and very thick - and even if we were to put a window there it wouldn't be very pleasant for people sitting in our very small (3m x 4rm) garden/back yard.
I suppose that, without any outside walls, one would have to vent the air through the roof via a pipe. And, come to think of it, not all kitchen cookers are on outside walls, but people still seem to find ways of sucking the cooking smells out of the house.

 

[MdB]

Another dumb question - where do all the extractor fans in all these internal windowless rooms vent the air too? If there is no external wall to the room, then they can only vent into the rest of the house, or am I missing something?

Under some conditions, I think you can vent into roof spaces (doesn't sound a good idea to me) but nominally they should all vent directly to outside.

 

[Flyfisher]

I hate the fact that our bathrooms don't have windows. Extractor fans are rubbish in my opinion - nothing beats opening a window for 10 minutes to clear the room of steam and unmentionable smells. . . . . . We could get a new extractor fan (I've no idea what spec our existing one is) but would it really make much difference?

I entirely agree that windows are best. But if you are windowless and having problems then it would be worth checking your fan rating.

First, they come in quite widely varying capacities - look for a litres/second figure, the higher the better.

Also, consider the ducting arrangements. The arrangement in MdB's picture is quite common but the longer the ducting and the more bends it has will all add up to create a significant air resistance. The result may be a lower airflow than the fan would normally deliver. Check the fan data for any ducting specs - look for things like maximum lengths and allowable number of bends. An extra bend might not make any difference if the overall length is shorter than the max. I think I read somewhere that a 90-degree bend is equivalent to 1m of 100mm ducting.

Also consider the fan type. Axial fans are more susceptible to ducting pressure than centrifugal fans.

Perhaps one way to start the design would be to calculate the volume of the bathroom then pick a time to fully replace the air, say 10 minutes. Work that out as an overall litres/minute figure and that's the minimum spec for the fan. If the fan is wall-mounted then that's all you really need but for a windowless room there will probably be a need for some form of ducting. Again, check the fan specs for design tips before arbitrarily increasing the fan size or type, or increasing the size of the ducting - all these things will increase the airflow.

 

[CatherineB]

Errr... at this point, I will have to abandon my attempts to understand, and leave it up to the architect and builder!

Back to the stripping...
(wallpaper)

 

[Flyfisher]

Apologies if I've made it all sound too daunting, it wasn't the intention. A lot of things can seem complicated overall, but break things down into stages and each bit can be quite simple. Just take things slowly and step-by-step.

Not that I've got anything against stripping as an alternative, you understand. :wink:

 

[Juju]

Our main bathroom vents outside - just enough space on outside to do so between back wall and rear extension but not enough room for a window. I think the downstairs loo also vents outside and ensuite vent somehow connects with the main bathroom - I will investigate further! Thanks FF for the info - I'll try and get my head round technical stuff this weekend or rather hand it to Mr Juju who is more scientifically minded than me. Plus I'm distracted by my second fall down the stairs this week and my back is agony (not that I'm trying to compete with Penners' bad back). These things always happen when you planned a weekend of digging the garden and several trips to the tip...
Juju

 

[CatherineB]

Apologies if I've made it all sound too daunting, it wasn't the intention. A lot of things can seem complicated overall, but break things down into stages and each bit can be quite simple. Just take things slowly and step-by-step.

Not that I've got anything against stripping as an alternative, you understand. :wink:

You're alright, FF, it's not you, it's me! And MdB's picture was, in fact, extremely helpful. Up into the ceiling and out under the eaves; that's all I really need to know: a) we have to have it, and b) this is the recommended way to do it.

Juju, take care of yourself, lots of rest this weekend! A bad back can leave a legacy for years - at least on PPUK!

 

[AMc]

If you're specifying a new extractor fan look at the noise output too lower dB = quieter.
Noisy fans are a major reason for people disconnecting the overrun timer. A small increase in cost for a quieter fan will be worth the money - it's the fitting that will cost. I would also suspect a quieter fan means a better made mechanism therefore a longer lifespan.

 

[Flyfisher]

Wickes and Screwfix have lots of ventilation bits.

Here's a factsheet that might be more concise than my ramblings:
http://www.wickes.co.uk/content/ebiz/wickes/resources/images/gil/93.pdf

Here's a kit that would do the job shown in MdB's picture:
http://www.wickes.co.uk/Low-Noise-Extractor-Fan-Kit-with-Timer/invt/199807

Not recommendations as such, but examples of what's available - including AMc's good point about noise.



And please be careful on those stairs Juju!