bathroom extractor fan

[vicky whitworth]

Hello, this isn't strictly speaking an old building question but we are having a bathroom extension added on to our old 1760 rubble stone cottage (not listed) and apparently building control are going to insist we have an extractor fan in the bathroom - despite there being two, opening casements. We have gone to lots of trouble to design the new part in keeping with the old (as much as you can with an extension) and used lime, etc. Our builder says the only way round it is to install the fan, let building control see it and then take it out again. Extractors are the devil's spawn in my eyes, and also, in this case, unnecessary. Does anyone have any suggestions to get round this? Will my argument about the two opening windows carry any weight? Many thanks, Vicky

 

[Penners]

What's your big problem with extractor fans? They'll help keep the air circulating in what will inevitably be a damp, steamy room, and they also help to freshen up the atmosphere after... ahem... need I say more? You may have windows, but will you open them in winter?

Modern fans aren't very noisy (particularly if you buy an "extra-quiet" one), and their electrical consumption is modest.

 

[middi]

I agree with Penners, bath and kitchens fans are invaluable to get rid of excess moistures and smells. Even if they are not switched on, the tricle air flow is usually enough to " freshen up" the air.

 

[Gervase]

They can be fitted fairly unobtrusively through rubble-stone walls, but making the hole, even with a top-quality diamond core drill, is an absolute b*gger. On one project recently I had to drill four cores through three-foot rubble-stone walls - including one at 45 degrees for a soil pipe ventilation stack - and it's not a job I'd want to do again in a hurry!

 

[Penners]

I had to drill four cores through three-foot rubble-stone walls

Here in my bijou East Anglian timberframe residence, I have a smug smile on my face. :wink:

 

[Flyfisher]

This article suggests that an opening window does not meet building regs: http://www.telegraph.co.uk/property/main.jhtml?xml=/property/2006/12/13/plevel10.xml

 

[Pford75]

It's also possible to fit the fan in the ceiling and vent via tube through the loft space and down through the soffit (assuming you have them). For my money, this is a much less obtrusive option

 

[Lime]

If I didn't want an extractor fan I'd do what the builder suggested.
The wiring would remain making re-installing the fan again quite easy.

 

[Penners]

It's also possible to fit the fan in the ceiling and vent via tube through the loft space and down through the soffit (assuming you have them). For my money, this is a much less obtrusive option

I quite agree. We have one in the bathroom like that, and apart from its hum you'd barely know it was there. This solution could also avoid a severe attack of "Gervase Elbow".

 

[skier-hughes]

I'm with Vicky on this one. I'm putting in an en-suite and am going to have to fit a fan, much as I hate them.
It goes back to my age old moan, why make me fit double glazing in my nice old house because we need to stop those draughts and conserve enrgy and then tell me I need trickle vents to produce a draught to change the air.

So, why do I need a double glazed window in my en-suite and pack it all round with insulation, when I have to fit a means of changing the air all the time.

I have an opening window, I do have my windows open often in the winter....... it's best to get used to the cold than try to heat myself up


GGgggggrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrraham

 

[Flyfisher]

As I've posted before, recommended ventilation for 'healthy living' suggests room air should be changed four times per hour for normal rooms and seven time per hour for kitchens and bathrooms. That's every 8.5 minutes for the bathroom. OK, perhaps this only applies while actually in use but even for normal room it's a total air change every 15 minutes. So all the 21C air you've just paid through the nose for CO2-producing fossil fuels (mostly) must be thrown outside and replaced with nice fresh 5C air (depending on time of year of course) to be heated again before being thrown out again in 15 minutes time.

No amount of double glazing and insulation is going to prevent this but I don't detect any great push for heat exchanger systems, which would (at great cost in both financial and disruption terms that is).

Insulation vs ventilation seems to be one the big conflicting issues in building design.

 

[MdB]

For info, using a 120m^2 floor area house with a complete air change every 15 minutes from 5 degs outside to 20 degs inside requires 6kW of heating just for the air.

(((120 (m^2)) x (2.3 m) x (15 K) x ((0.001297 (J / (cm^3))) / K)) / (15 minutes) = 5 966.2 watts)

 

[DaveBrigg]

We had an extractor fan fitted in the bathroom, which the builder wanted to vent through the slate roof using a dark grey plastic thing which was supposed to look a bit like a raised slate. Instead, I bought some narrow ducting (used for kitchen extractor fans) and routed it between the slates and the bathroom ceiling. In our case it feeds into a shed, but if necessary it could stop at a level just above the lowest slate and remain invisible. The fan doesn't work - it had a missing component and by that stage was not in a fit state to be returned. Instead, we open the window a little...

 

[Craig]

I believe that that particular part of building regs is only enforecable via general health and safety - so they would have to prove that your approach to ventilation was going to cause harm...

 

[MdB]

The law (Building Regulations Act 2000) requires the following:

Means of Ventilation:

F1. There shall be adequate means of ventilation provided for people within the building.

That is it. There isn't any more.

Building control who enforce the above have issued approved document F which if you follow it (ie have an extractor fan) then you automatically meet the requirements and building control will accept it. This does not mean that you have to follow document F by law. If you can prove that your methods of ventilation (ie opening a window) are "adequate" then you have met the requirement by law. The problem of course is that building control are the people who decide what is adequate and what is not and I would expect a long hard struggle to get anything past them which isn't in approved document F.

 

[Craig]

Exactly - if you check around you can also find how each individual part is enforced. There are only a few sections where there is a specific law, a lot is enforeced by way of other pieces of legislation.

However, knowing this doesnt help much when they are saying "no"

 

[chuckey]

I would be very careful when installing an extractor fan. There is a possibility that the bathroom could implode and cause great structural damage.
Frank

 

[FamilyWiggs]

I would be very careful when installing an extractor fan. There is a possibility that the bathroom could implode and cause great structural damage.
Frank

I wouldnt worry Frank - the Large Hadron Collider has already created a blackhole that is munching its way through Switzerland (has anyone phoned to check it is still there?) Your average extractor fan vacuum potential pales into insignificance in comparison.

We're all doomed. Doomed I tell ye.

 

[Penners]

There shall be adequate means of ventilation provided for people within the building.

Your lapse into your native Swahili a bit higher up the page is excellent guidance for specifying air changes. However, our Building Inspector told me that the normal approach for a bathroom is to look for a fan specified at 15 litres/second. He didn't seem overly interested in the volume of the room.

 

[Flyfisher]

If my arithmetic if correct, 15 litres/second is 7650 litres every 8.5 minutes (for 7x change of air per hour), is 7.65 m3 equating to a floor area of 3.4 m2 assuming a ceiling height of 2.25m. I'd guess the average bathroom is larger than that.

Some interesting info here: http://www.tlc-direct.co.uk/Technical/Ventilation/Ventilation4.html, which suggests much higher rates of air changes than the 4 or 7 I mentioned earlier. For the insomiacs out there, it also includes a link to the official ventilation requirements of the 2000 building regs.