Help! Mould smell in wetroom after slow leak and mould removed behind false wall

[london]

Hi everyone, new to this forum and would greatly appreciate any advice.

We installed a walk in shower with a false wall to conceal the shower, toilet and wall hung sink pipes. There was a slow leak which led to a lot of mould growth. We opened the shower pockets and cleaned pretty much all the mould, perhaps left a little within the joints itself as it was unreachable , but the smell was gone. Put in a vent to allow air to come out behind the false wall. Dried the room thoroughly over 5 weeks with a dehumidifier.

After 2 days of use of the shower, the smell has come back. We took out the shower pockets again and could not see much mould!

The extractor fan seems to be working. The room is still quite damp so going to find a way to secure the sash window so we can crack it open all day. But the smell is coming from behind the false wall, where we don't understand where moisture could be going back as we fixed the leak already. Could it be going backwards from the bathroom into the false wall via the vents?

Anyone with false walls in bathrooms have a similar experience?

We are planning to paint the shower frame (wood) with some mould-proof paint now or bitumen, and seal all joints in case there are still mould spores stuck in there.

Really at a loss of what else to do now!

Any advice greatly appreciated!!!

 

[SimonG]

Is the shower on an outside wall? What construction is the outside wall? Is there any air movement within the false wall?
May not be a leak but condensation if you cant find any other leaks. Or not fully dried out from the leak.

 

[Murdoch]

FWIW the extractor May well be working but what heating do you have in the bathroom?

Ventilation and heating are required

 

[Gasmk1]

try hiring a dehumidifier for a week and drying it out also bathroom should be well ventilated

 

[london]

Is the shower on an outside wall? What construction is the outside wall? Is there any air movement within the false wall?
May not be a leak but condensation if you cant find any other leaks. Or not fully dried out from the leak.

Hi thank you for your help. The shower is on a shared wall facing the neighbours house (terrace house). The wall to left of shower head faces outside. The ventilation fan is on this wall. We don’t have any ventilation behind false wall as we felt it should be a closed system. We have anti condensation lining on the toilet cistern but not on the other pipes within false wall.
Should we consider just installing a ventilation fan behind the false wall leading out or lining all pipes to avoid condensation? We felt we had fully dried it out as no smell was present until we starting using the bathroom again.

thanks again!!
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FWIW the extractor May well be working but what heating do you have in the bathroom?

Ventilation and heating are required

thank you for your help,we have a small towel radiator on the wall opposite the sink.

Only one ventilation fan in bathroom but not behind false wall

 

[Murdoch]

Hi thank you for your help. The shower is on a shared wall facing the neighbours house (terrace house). The wall to left of shower head faces outside. The ventilation fan is on this wall. We don’t have any ventilation behind false wall as we felt it should be a closed system. We have anti condensation lining on the toilet cistern but not on the other pipes within false wall.
Should we consider just installing a ventilation fan behind the false wall leading out or lining all pipes to avoid condensation? We felt we had fully dried it out as no smell was present until we starting using the bathroom again.

thanks again!!
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thank you for your help,we have a small towel radiator on the wall opposite the sink.

Only one ventilation fan in bathroom but not behind false wall

One small radiator us unlikely to produce much heat ....

 

[king of pipes]

Ventilation is very important in a bathroom moisture levels can be very high you need to replace this with regular air changes 8 changes per hour passive air is worth considering in this situation to vent the void . Kop

 

[gpbeck]

I would check those recesses in the false wall within the shower space which if not properly done could easily let water through. A flat wall is much easier to seal.