Ceiling or wall extractor fan for small bathroom?

[JP_]

I will soon be renovating the old shower room, removing the shower and putting in a bath again. It will be an occasional use bathroom, as we mostly have showers (new shower room built for that). Currently there is an old extractor fan in the ceiling that needs replacing.

This room has had condensation mould issues, so I will be overboarding the ceiling and might even put insulated backed plasterboard on the ceiling for this, as well as insulating the external wall and under the floor. The house is solid 9 inch brick walls, but there is an old covered air vent on the wall.

I used this in the new shower room, and all seems OK, but wondering, which is generally best? There is a window in the room too which is usually on the catch after showers.

 

[JohnD]

water vapour is lighter than air so it naturally rises towards the ceiling, so a ceiling mounted fan will catch it better.

If you have room for an extractor above the ceiling, in the loft, with a duct going through the wall or eaves, you can have an inline ducted fan which can easily be three times as powerful as a typical wall fan, and quieter, so a better job all round. They are bigger and more expensive.

Fans work more efficiently if the door and window are closed, and replacement dry air enters through the gap under the bathroom door (displacing the warm, humid air upwards, without mixing).

As you have uninsulated solid walls, they will be cold and prone to condensation. You might be able to fit an insulating rigid foam board to the walls and tile over it but I have no experience of that.

 

[JP_]

Thanks John. I'll be insulating those wall, the usual 5cm kingspan, boarded over, then tiled / skimmed & painted.
There's very old loft insulation above, might actually clear all that out and get it all tidy. Spring job.

 

[foxhole]

Good powerful fan will remove moist air before in can cause problems , don’t skimp on a cheap model .

 

[JP_]

Don't worry, I wont. Fan position is what I am asking about.

 

[foxhole]

Don't worry, I wont. Fan position is what I am asking about.

Ceiling above shower