Solid floor plaster. Many solid floor are build with plaster touching the ground, this causes upward absorption. Consider removing the ground floor skirting board, cutting base of the plaster by 10 – 20mm back to brick (chisel, grinder or better still Osc
Plaster should not touch a solid floor. Consider instructing a general builder to temporarily remove the skirting board to the front area, cut the lowest 10 – 20mm of plaster back to brick to stop the link between plaster and floor. Then run a ~10mm thick
Plasterer’s beading is typically made of mettal, although plastic is available. The metal bedding losses hea rapidly causing condensation and often resulting in calcium sulpahte salts to come to the surface by the beading.
Solid floors are prone to condensation because of heat loss close to the ground. The impermeable surface acts as an amplifier, resulting in water under the skirting board. It is also common for plasters to allow the plaster to touch the solid floor. plaster is absorbent. The result is often misdiagnosed as rusing damp. The simpest solution is 1) improve ventilation, 2) seal up at the base of the skriting board, 3) cut the plaster back at the base of the wall by 10 – 20mm back to brick (chisel, grinder or better still Oscillating Multi Tool, such as Bosch), 3) Run a bead ~10mm of a absorption reducing Thixotropic cream such as DryZone by Safeguard (Amazon etc), along the exposed brick. Replace the skirting board.