Bathroom Extractor Fan Requirements?

[jungle_jim01]

Hi, i'm just about to start working on our new bathroom (originally a bedroom). It's a medium sized room with a large sash window. We're planning on a bath with a handheld shower head and a sink. The room has one fairly large sash window, so do i need to install an extractor fan as well. I know it's recommended to have a fan but is it the requirements? The problem being that apart from window (which goes all the way to ceiling height, the rest of the external wall is chimney breast (unused, but open fireplace in room). Can i vent into this or does anyone have any bright ideas? Running something up into the attic and then out may be an option but quite a bit of hassle and i don't really like the thought of having something on the outside of what is a nice stone wall.

Thanks for your advice.

 

[MdB]

http://www.planningportal.gov.uk/buildingregulations/approveddocuments/partf/approved

The requirement by law is Section 2.1 of the above in green. This states only that there has to be "adequate" ventilation but doesn't specify what this means.

The rest of the document gives details which if you meet them then you automatically meet the requirements. However, there is nothing to say that you must do it that way. You can come up with your own scheme such as "instruct owner to open window when using shower / bath until condensation has been removed", but if you want BC to sign off, you will have to get BC to accept that your scheme is "adequate". This might be difficult. If BC aren't involved - do what you like.

I had difficulty in finding a sensible place to fit an extractor in my bathroom. I ended up going up into loft and out through the eaves which was a bit fiddly but not too bad. The narrow gap required a wide tube of little height to go through the gap but works fine and is hidden from below. I would avoid going through the wall if you can. It doesn't look good and the short distance can be draughty and noisy.

 

[tobydog]

Our cottage is thatched and although our bathroom is upstairs we don't have a window. The previous owners fitted a ceiling mounted extractor that took the steam through the loft via a 4" pipe to the end gable. It results in a pretty ugly exit but we can't do much about that now. The horizontal travel is at least 15ft. The existing extractor was very noisy and sounded as though the bearings had gone. We had an electrician fit a new one for us, however, we didn't think to specify what sort on the basis he should know better. We later found out that he fitted a wall mounted type which, it turned out, didn't have the puff to effectively get the steam more than a few feet let alone outdoors (another gripe I could have added to the competent electrician discussion). We have now fitted a much more powerfull extractor that sits in the loft like a mini jet engine and is very effective. Just a word to the wise that if you go the loft route, you may need to upgrade the spec.

 

[Flyfisher]

Some useful info here: http://www.wickes.co.uk/content/ebiz/wickes/resources/images/gil/93.pdf

The fan is not the only consideration when designing an extractor system. Although a fan will be rated for a certainly volume of air per minute (or similar), its actual performance will depend on the nature of the ventilation ducting. Long runs and every bend will reduce the volume of air that can be moved by a given fan because (I think) of back pressure. Centrifugal fans maintain their performance better with long ducts/many bends than do axial fans.

I remember reading a very useful design guide for such things that explained the effect of each bend in a ducting system and allowed very easy calculation of the fan capacity required for a given extraction requirement. Unfortunately, I can''t find it anywhere. But I know I found it on the web somewhere so presumably it's still out there.

 

[skier-hughes]

My ensuite has a window, it opens, it's sorted :wink:

 

[geoff]

I put in a (very) small en-suite toilet and basin. On the subject of ventilation, I told BC it had a 'manually operated, variable aperture fenestrative ventilation device'. It kept them quiet....

 

[mivec]

We've just had an en-suite wet room created. It was originally the outside loo which we included as part of the bedroom by knocked through an external wall. It has it's own sloping roof that we have fitted a skylight in so assumed we wouldn't need an extractor fan but the building inspector insisted that we did.
As we had a window he said we could have it on an isolation switch so we can turn it off when not needed.
I'm really glad we've got it now and we use it all the time. Opening the skylight seems to do nothing to help clear the steam, maybe because it's in the ceiling not the wall.
We are also looking to upgrade the fan, as the cheap one we originally bought in a rush struggles if you have a long, hot shower.

 

[88v8]

Hi, i'm just about to start working on our new bathroom (originally a bedroom). It's a medium sized room with a large sash window. We're planning on a bath with a handheld shower head and a sink. The room has one fairly large sash window, so do i need to install an extractor fan as well. I know it's recommended to have a fan but is it the requirements? The problem being that apart from window (which goes all the way to ceiling height, the rest of the external wall is chimney breast (unused, but open fireplace in room). Can i vent into this or does anyone have any bright ideas? Running something up into the attic and then out may be an option but quite a bit of hassle and i don't really like the thought of having something on the outside of what is a nice stone wall.

We have fans in the loo, bathroom and kitchen, the equivalent is now called the Roomvent T
http://www.airflow.co.uk/products_/pg_RVFN/71616301
which seem expensive but they've given close to 30 years of silent trouble-free running. A world away from the rattling horrors you might find in a DIY superstore.

Like you, I didn't fancy an ugly plastic external grille, so for the bathroom I made one from mahogany and lead. It doesn't matter what you make it from so long as it blends in with your house.
Or as you say, you could vent into the attic and then use trunking to run the air out of the eaves. The Roomvent will work with any length of trunking you're likely to need.

Ivor