Underground wall damp

[Tommygun3000]

Ill try and keep this as simple as possible but I’m after some help from you kind folks..

just moved into a 230 year old property that was basically fully rebuilt in 1970 it is an unusual layout in that one side of the ground floor is underground (front of house looks like a bungalow but it’s 2 story) this underground wall is damp inside the living room, had a damp specialist out who recommended a waterproof bembrane but doing some googling I’m wondering if the opposite is the best option and lime plastering to allow it to breathe and ventilate the moisture away!? Another thing to add though is that the house is cement rendered on the outside so this moisture would only have 1 way to go 👎 the wall currently is themalite blocks with some kind of tanking slurry and the slurry is obviously failing after all these years

 

any help would be very welcome as googling is sending me in circles and I don’t know what is the correct course of action 

 

cheers

[Redbeard]

What I'd do if it were mine: Can you excavate and (at least temporarily) expose that wall? Do that, bubble-membrane with good detailing and back-fill with large aggregate ensuring lots of voids and you'll have good drainage around that area. Now you can hack off the tanking slurry and plaster in lime (which I like) or gypsum (which I don't, much). Any contaminants in the blocks will probably leach through lime as much as gypsum. Lime is good; I really like it, but it is not a universal panacea for moist walls.