Bathroom with no window - fitters says over-run is optional?

[Jaunty]

First a quick thank you to diynot.com for exisitng, my first port of call for any diy issues!

We had our downstairs bathroom refurbed successfully, and had the same fitter back to put a new one in upstair. It is in the centre of the house so no windows. A bath with shower, WC & sink, small in size. The fitter supplied the fan. Electrics done by a registered sparkie. We have an inline extractor fan in the ceiling which vents through the roof eaves. Early in the job I pointed out it did not run on, but just turns on and off with the light switch. I had assumed it would be on a timer (like the one I had specified for downstairs) but I was reassured the fan was so good it would be fine. Now at the end of the job I have read if there are no windows there needs to be a run on?:

http://www.fantronix.com/acatalog/Product_options_explained.html

I pointed this out to the fitter who got a bit shirty with me and replied
"The building regs for this are a bit of a grey area. The minimum requirement is 15 litres per second. The fan you have extracts at 68 litres per second. So even without an over run this fan would extract more than twice the minimum requirement including the 15 minute over run".

I have tried reading & re-reading Building Regulations part F to no avail. This thread on IET seems to know what it is on about:

http://www.theiet.org/forums/Forum/...ORUMVIEWTMP=Threaded&catid=205&threadid=38986

and to summarise I think it says if no windows there should (not must?) be an over-run for new builds. If it is not a requirement I think I still would want a timer, and will pay to get one fitted/the fan changed. If it is a requirement the fitter should really sort it though, hence my long post! Thanks for any input.

 

[bernardgreen]

It is common sense to have an over run as moisture on walls etc does not dis-appear when you turn off the light.

"The building regs for this are a bit of a grey area. The minimum requirement is 15 litres per second. The fan you have extracts at 68 litres per second. So even without an over run this fan would extract more than twice the minimum requirement including the 15 minute over run".

The 68 l/s is when the fan is moving air without any obstruction. Ducting and grills will reduce the flow and unless there is a way for replacement air to enter the room then the fan will not be moving any air when the pressure in the rooms drops. A gap under the door or a louvred panel in the door are essential.

 

[electronicsuk]

In a room with no openable window (i.e. an internal room) an intermittent extract fan should have a 15 minute overrun. In rooms
with no natural light, the fans could be controlled by the operation of the main room light switch.

I don't see any mention of the omitting an overrun timer just because you have a higher intermittent extract rate that required by the regs. Admittedly this is under the 'New Dwellings' heading, but much reference is made within the existing dwellings section to table 5.2a, which may be worth a look.

 

[Jaunty]

Thanks I agree a timer is preferable and will fit one (or a fan with one). But the question is whether it is a requirement?

 

[electronicsuk]

This may be of interest to you:

7.23 If you carry out any ‘building work’, and there is an existing extract fan or passive stack ventilator (or cooker hood extracting to outside in the kitchen), you should retain or replace it. However, if there is no existing ventilation system you need not provide one. Replacing an extract fan or cooker hood with a similar type, and using the existing cabling, need not be notified to a Building Control Body.

However, the document does not explicitly state a requirement for the ventilation to be compliant with the current regs, only that the ventilation provided be no worse than was present before the works commenced. Will await the opinions of others on this one!

 

[JohnW2]

However, the document does not explicitly state a requirement for the ventilation to be compliant with the current regs, only that the ventilation provided be no worse than was present before the works commenced. Will await the opinions of others on this one!

I'm not totally clear of the sitation from the OP. If we are talking about the refitting of an existing upstairs bathroom, then it's difficult to argue with your interpretation above. However, the OP talks of 'a new one' - and if that means a new bathroom (where there was no bathroom before), then common sense (yes, I know.....!!) would suggest that there ought to be a requirement to comply with current regs - but I haven't a clue whether that's how it is!

Kind Regards, John.

 

[Jaunty]

In a room with no openable window (i.e. an internal room) an intermittent extract fan should have a 15 minute overrun. In rooms
with no natural light, the fans could be controlled by the operation of the main room light switch.

I don't see any mention of the omitting an overrun timer just because you have a higher intermittent extract rate that required by the regs. Admittedly this is under the 'New Dwellings' heading, but much reference is made within the existing dwellings section to table 5.2a, which may be worth a look.

Thanks! Have now been able to find thissection in the F1 document. It will help me discuss who pays to fit the timer if I need to.

 

[Taylortwocities]

Jaunty.

Its not just a matter of swopping the fan. You'll need 3 core and earth cable to the fan from the lighting supply. I'll bet they only ran in 2 core & earth.

 

[Paul_C]

Now at the end of the job I have read if there are no windows there needs to be a run on?:

http://-/acatalog/Product_options_explained.html

From the link:

Building regulations state that if your room is enclosed with no opening windows, then a fan with a run-on timer must be used.

Actually, they say no such thing. The statutory requirement is only that "There shall be adequate means of ventilation provided for people in the building."

The section on control of intermittent extract in the Approved Document for Part F does contain the following:

In a room with no openable window (i.e. an internal room) an intermittent extract fan should have a 15 minute overrun. In rooms with no natural light, the fans could be controlled by the operation of the main room light switch.

Approved Documents are not regulations, and are only guidance as to how you might comply with the building regulations. It does not mean that you will not comply with them if you don't do everything they suggest. The 15-minute overrun suggestion is rather vague anyway - 15 minutes from when?

However, the above quote appears only in the section for new dwellings anyway, not for refurbishments or alterations to existing dwellings. So is there an absolute requirement for a timer fan in your situation? No.

 

[Jaunty]

Thanks all. The upstairs bathroom is new new. We had a WC upstairs only, which has been removed, new stud partition walls and new WC, sink & bath/shower put in in a different part of upstairs. But if it is not a requirement to have a timer, just a preference, I can’t really make the fitter responsible for the cost if I did not specify it in advance. (I feel he should have specced one as standard, or at least offered me the option, but that is another matter). However the electrician has certified everything to part P, I will ask him directly about the wiring and adding a timer/timed fan.

(On a different but related note I now realise this should have had Building Control approval which the fitter has never mentioned to me. Sigh!).

 

[Taylortwocities]

It is the electrician who must notify the local authority. This is a legal requirement (unlike the fitting of a fan with an over-run).

Is he registered? Is he listed HERE??

 

[Jaunty]

It is the electrician who must notify the local authority. This is a legal requirement (unlike the fitting of a fan with an over-run).

Is he registered? Is he listed HERE??

Will check, confident he is registered as had to do some addtional work on the wiring before he would part P it. But Building Control for the bathroom (eg changing location of WC and extending (above ground) the soil stack) would not be the electrician, would it?

 

[securespark]

Never mind who's responsible. You may not need a timer fan, but I think it prudent to fit one.

 

[Paul_C]

If you do fit a fan with a timer though, don't make the mistake of having it linked to the light switch. Do you really want the fan to turn on and then continue running for 10 or 15 minutes if you just pop into the bathroom during the night for half a minute? Put it on its own separate switch.

 

[JohnW2]

If you do fit a fan with a timer though, don't make the mistake of having it linked to the light switch. Do you really want the fan to turn on and then continue running for 10 or 15 minutes if you just pop into the bathroom during the night for half a minute? Put it on its own separate switch.

Is that allowed by the relevant regs when there is a requirement for 'adequate ventilation'? It seems a bit odd to leave the householder in manual control of whether or not the ventilation is operative.

Kind Regards, John.