En suite ventilation, mid-tier flat, no external wall

Hi,

I'm thinking of converting a 236x85cm closet into an en suite and I'm struggling with the ventilation, as there is no access to an external wall or loft space. Three internal walls are adjacent to the master bedroom, hallway and (soon to be after the wall is taken down) kitchen/lounge, while the fourth wall is shared with another building. There are other flats above and below.

Is it advisable to extract the air into the bedroom or the kitchen/lounge? If not, I may have to skip the shower.

Thanks

You cannot vent warm moist air into another room. It has to be vented to outside open air or you are going to have terrible condensation problems.

Unless someone can come up with some viable solution it looks like you will have to forgo the shower.

Does the kitchen have an outside wall?

Only thing you can do is box in a duct through one of the rooms to the outside.

Does every room really taper like that? What an odd shaped bunch of rooms!

if you are ducting via another room, you will need to take account of the distance, and install a powerful enough fan to draw the steam to the outside.

I did this for a friend who lived in a flat. I used the flat rectangular duct designed to run above kitchen cupboards that is used with kitchen chimney hoods. Due to the nature of its intended use it is pretty heat resistant.

It was fixed at high level right up to the ceiling, and boxed it in with plasterboard on a timber frame. Then to make it look as if it was intentional, I fitted some LED downlights in the bottom of the boxing, each lighting a picture below. The box will need to be deep enough to give the recommended clearance for the lights for ventilation. LED lights are better, because as well as saving energy, they don't generate anywhere near as much heat as halogens.

Use a centrifugal fan as these generate more pressure than axial fans in order to overcome the pressure loss in the duct.

The end result was hidden duct and a nice room feature too.

What is the construction of the ceiling?
You can get slim rectangular conduit that is designed to fit between the joists.
Otherwise you can box it in below the ceiling. I have this from my bathroom along the hall to a vent in an outside wall. (My fan is not really powerful enough for the length of tube; I keep thinking I ought to replace it with a more powerful one. If anyone can recommend a fan that is powerful but not too noisy, that would be useful.)

If you box in,you could go for an inline fan and make some sort of access to it for if its ever required.

This way you don't end up with a large centrifugal fan on the wall of the bathroom, and inline fans are often more powerful and quieter

Thank you for the good ideas.

The rooms indeed taper like that, almost all the walls are out of square, which will make fitting the kitchen fun.

There should be enough space in the ceiling for a duct to run along the joists, but I would have to go across at some point to reach an external wall. The kitchen/lounge and the small bedroom (to become the main bathroom) do have external walls. Currently, the water and soil piping is on the south wall of the kitchen and bathroom.

Outside duct in the kitchen/lounge is a possibility but there'd be quite a bit of distance to cover (5-6m with a bend), so I don't know if any fan would be powerful enough.

I also thought about building a duct and venting into one of the chimney breasts, but they're both sealed in my flat and I strongly suspect it's the same in the flat above, so I don't know if it's possible.

Here's the new layout that I'm thinking of. I wonder if it'd be possible to build a duct on the north wall of the kitchen/lounge and link it to the duct on top of the kitchen cabinets?