Bathroom extraction help

[m0t]

We have a downstairs shower room that has a loft space above it. When we first moved in the room steamed up and got mouldy so I fitted an extractor. The duct goes in to the loft space then out the roof.

I'm having a loft extension done and there is now going to be a full size bathroom directly above do I'm going to lose my downstairs shower room extraction.

The only outside wall has a window in it the length of the room and above the window is a lintel, so I can't drill through it.

Any ideas for a solution? The only thing I can think is going up in to the new room above and then out through the wall but that would mean the fan would be under a bath and I'm not sure it will fit.

 

[KenGMac]

m0t, good evening.

Suggestions?
1/. Fit the fan within the [soon to be] floor joists, then duct out the [new] wall and vent to atmosphere within the space below the [new] bath

2/. Fit the fan to the wall below the bath, duct to it and it can vent there, the wall mount could be very low under the bath.

3/. Form a vertical duct housing within the new bathroom and vent the ground floor bathroom vertically passing through the soon to be new bathroom.

Have a look at rectangular ducting? can be fitted into a smaller space.

Ken.