Powder room extractor fan

[Alwaysmore]

We are replacing the toilet in our understairs powder room and am unsure if I need to put in an extractor fan if the small room only contains a toilet and a small sink?
As it situated under our stairs and it doesn’t have a window.
It has an old vent on the wall as it backs on to the disused chimney in the foyer, but I don’t think it does anything.

Is anyone familiar with the code? Just not sure it’s necessary if the room doesn’t have a shower or a bath?

It would be wise.

You say there is no window.

Where is the nearest external wall?

Yep any room with water plumbed needs an extractor as I understand it.

That's not quite right, but it qualifies as a room with sanitary accomodation. The rate required is less than a room with a bath, I'd suggest a modern "silent" fan coming on with the light switch. For a 100mm fan, about 80-100 cu.m/hr is typical and IMO suitable. I have a feeling you will need a duct to run to the exterior

I think paras 1.17ff are relevant.

https://www.gov.uk/government/publications/ventilation-approved-document-f

Haha at powder room. It's a downstairs bog.

Thanks everyone for you advice.
@PigletJohn its under the stairs on a shared party wall, so no window.
Id like to make sure it meets code when we renovate it but I wouldn’t bother with an exhaust if it wasn’t required.
Does anyone know if I’d have to link it to the light switch or could I have it on two separate switches.