ventilation in a bathroom

[davep]

my average 3 bed semi has a bathroom with two outside walls. It has a 9" sq hole with vents to the outside. Do I need to supply extra ventilation in the form of a ceiling fan and ducting in the loft? davep

[Mary Fisher]

From our experience you'd be better with some form of extra ventilation but you don't need to haveanythingcomplicated like aceiling fan and ducting if you already have thehole in thewall. .

At the suggestion of someone here we've recently replaced the inefficient extractor fan in the hole with a low wattage rh sensitive automatic fan. It works very efficiently (and very quietly) and we don't have to think of switching it on or off - although we can if we want.

We're getting idle in our dotage :-)

Mary

[davep]

thanks for the reply. I'm mainly concerned from a building regs perspective. An electrician friend has said I need one, connected to lighting loop with fused outlet outside

[Christian McArdle]

Replace the fixed vent with a fan. Job done. You can put ducted stuff in the loft if you want, but just reusing the existing hole will be quicker, cheaper and more effective.

Christian.

[davep]

the fixed vent is within zone 1. okay I can use a product that is IPX4 or selv but I don't think I can run this from the lighting loop. What I really need to know is whether in fact a fan is necessary. davep

[Mary Fisher]

?

That only applies if you want the fan to come on every time you switch on the light - and only when you switch on the light, even during the day. We didn't want that so ours is independently wired. It makes sense in many ways. Power saving is themost important one.

Mary

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[Dave Fawthrop]

|my average 3 bed semi has a bathroom with two outside |walls. It has a 9" sq hole with vents to the outside. |Do I need to supply extra ventilation |in the form of a ceiling fan and ducting |in the loft?

I have had no problems with *two* square inches ventilation in my bathroom. Average semi, four adults.

[David Hansen]

On Fri, 21 Apr 2006 11:04:04 +0100 someone who may be davep wrote this:-

They are not retrospective. If you were to do a lot of work on the house then a fan might become "necessary" under the building regulations, though since you didn't say where you are it is difficult to go much further.

Does the bathroom have a window? If so, does this not provide adequate ventilation without making your electricity meter go round?

Three incorrect statements.

Sadly, mechanical ventilation is required in places for new buildings (and perhaps extensive works), but not retrospectively in existing buildings.

Mechanical ventilation can be fitted to any suitable circuit, providing that this is done properly. That could be a lighting circuit, or not a lighting circuit.

Fused connection units can be placed inside a bathroom, provided they are in the correct places, or outside.

[Christian McArdle]

Teenage girls? That's when you get condensation.

Christian.

[chris French]

Why not?

As has been pointed out probably not from the POV of building regs.

Only you are in a position to judge whether the bathroom ventilation needs improving.

[Guy King]

The message from "Christian McArdle" contains these words:

And teenage boys, when they discover girls.

[surveyor]

If its new work ie forming a bathroom for the first time then a fan is required if its an existing bathroom then no mech extract is required

[surveyor]

If its new work ie forming a bathroom for the first time then a fan is required if its an existing bathroom then no mech extract is required

[surveyor]

If its new work ie forming a bathroom for the first time then a fan is required if its an existing bathroom then no mech extract is required

[Mary Fisher]

It might not be required by The Authorities but often it's desirable.

Mary

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[Harry Bloomfield]

davep wrote on 21/04/2006 :

The hole sounds excessively large for what I would guess is quite a small bathroom.

The best solution would be to install a small extract fan in the existing hole, a 4" or at most 6" fan would probably be adequate. This would draw air in from the rest of the house -helping to prevent the moist air spreading out from the bathroom - rather than having a drafty, open 9" square hole. You would also need to ensure all of the extracted air went straight out through the wall, rather than into any wall cavity there might be.

The best type to install are the ones with an automatic shutter, triggered by humidity and by PIR with delay timer. That means it would turn itself on if someone were to walk in and keep running for a set period, or keep running until the humidity falls to normal levels if someone has had a bath/shower.

Much better than the ones which need the light to be turned on before it will operate, as you don't normally turn the light on during the day when using the bathroom.

[daddyfreddy]

If you have outside walls then you certainly don't need ducting to go through your roof, that's when you don't have any outside walls and no other option but to.

[Mary Fisher]

Why on Earth would you need the fan to turn on just because someone walks in? Do you have one in other rooms in the house???

The best automatic one is goverened by humidity, not movement..

Mary

[The Natural Philosopher]

He is largely correct. Slap a fan in the hole in the wall. The ouside bit is not fused, its merely a double pole isolator.

You can choose between things that run off the lights direct., with a timer, or a humidity sensor, or combinations of these. Whilst you are at it, insulate the outside walls..if you can..

[The Natural Philosopher]

The regs say that electrical kit in bathrooms must be connected to a double pole isolator outside - or outside the zone anyway IIRC.

Whether that is on the light circuit, switched by the light switch, or what, is up to you.