Bathroom Walls - Always moist - Internal or External Insulation

[DIYTwinDad]

Hi,

My bathroom, which has not been renovated by the previous owner for decades, in a 1950s house, has two of its wall always wet/moist with droplets of water dripping constantly. This happens in Winter (and it has started already with the drop in temperature). The two walls are North and East Facing and the face directly outside (i.e no further room/building).

At first, I thought the moisture was there because of the shower. But I monitored last Winter and I could see that the walls remained moist even if the window is left open and even if there is no one using the shower. This issue if moisture has caused a lot of damp and mould on the wall and ceiling of the bathroom.

I am getting the bathroom refurbished and I would like to tackle this issue of the wall in one go. Can you please advise the best way forward?
I plan to have all the walls tiled, and install a good extractor fan (fan recommendations will be helpful).
Do I install Moisture resistant plasterboard before tiling? If not that, is it thermal plaster? or some sort of membrane to keep the wall warm and avoid moisture? I'm worried that if it is tiled over, the moisture will come back and cause the tiles to break off over time.

It is worth noting that downstairs, I have my kitchen which also has similar problems of two walls having moisture in Winter. This has caused damage to my kitchen cabinets too. Leaving windows open helps but not much and it also becomes impractical during Winter. I also have a dehumidifier which is sort of a band-aid temporary solution. The windows in bedrooms also become quite dewy (moisture) overnight.

I want a fixed long term solution to this very annoying and damaging problem.

Thank you for reading, I appreciate your help and guidance on this.

 

[jj4091]

You don't mention having any form of heating in either room. There will be those that disagree but in my opinion you cannot stop condensation without having a warm envoironment and warm surfaces that restrict the amount of steam that condenses on cold surfaces.

 

[foxhole]

Do you have efficient working extractor fans in kitchen and bathroom .
Do you dry washing in the home?

 

[DIYTwinDad]

You don't mention having any form of heating in either room. There will be those that disagree but in my opinion you cannot stop condensation without having a warm envoironment and warm surfaces that restrict the amount of steam that condenses on cold surfaces.

There is a towel rail heater in the bathroom, but there none directly on the two walls that get cold.

Do you have efficient working extractor fans in kitchen and bathroom .
Do you dry washing in the home?

There is no working extractor in the bathroom. There is only an extractor hole which is covered by a grill and nothing else. I plan to have an inline extractor installed when refurbishing the bathroom. I am also planning to tank the two walls with Mapei Shower Kit and then tile all the way across the 4 walls in the bathroom.
Somebody recommended to put moisture resistant plasterboard or thermal plasterboard before tiling. But that would increase internal thickness but most importantly, I am not sure how effective it would be in keeping the cold walls warm.
What would you recommend doing?

 

[foxhole]

You need an extractor fan , insulated plasterboard would help reduce cold wall .