Just taking a stab here, but I'm going to guess this is an older home with plaster walls and built on a grade level masonry foundation in a wet climate (UK?).
My best guess would be that the garden doesn't grade away from the flat(s) and the foundation/slab aren't waterproofed.
Masonry is essentially a sponge, and the only place for the water to go is up into the walls since you have impermeable flooring.
Here in Seattle, a common retrofit for slab-on-grade homes is to trench a perimeter footing drain around the house to relieve hydraulic pressure under the slab since our water table comes right to the surface in areas during the winter. (Water wells will become artisan in winter)
_TEOTWAWKI_ t1_iulzhid wrote
Reply to What is causing the damp on interior walls? by victor0nl1n3
Just taking a stab here, but I'm going to guess this is an older home with plaster walls and built on a grade level masonry foundation in a wet climate (UK?). My best guess would be that the garden doesn't grade away from the flat(s) and the foundation/slab aren't waterproofed. Masonry is essentially a sponge, and the only place for the water to go is up into the walls since you have impermeable flooring. Here in Seattle, a common retrofit for slab-on-grade homes is to trench a perimeter footing drain around the house to relieve hydraulic pressure under the slab since our water table comes right to the surface in areas during the winter. (Water wells will become artisan in winter)