Skirting board green damp powder

[simpleian]

Hi, wonder if anyone can help...

I have recently had to rip up my suspended timber floor on the ground floor due to woodworm damage to joists. Whilst doing this I cleared out all the excess soil and rubble that had accumulated and cleared the passages to the two air bricks. Following reinstatement of the new joists, installation of chipboard flooring and underlay/laminate I have started to notice a green powder forming on the skirting in areas of the room which are covered I.e. a sideboard in front of.

This brushes off ok but keeps coming back. I haven't glossed the skirting yet so it just has a primer. I'm assuming I have a condensation issue?

My initial thought was to put a layer of damp proof membrane behind the skirting, but would this really help?

Thanks

 

[Buppyjo]

Hi, I would also like advice on this if anyone can help? Decorated my little boys bedroom (2nd floor) earlier this year and since redoing new skirting on freshly plastered walls, a dark green damp powder has been forming on an area covered by a cabinet. This was not an issue before redecoration so cannot understand why it is now happening. Skirting board is moisture resistant MSG and has been primed, under coated and glossed. House is 1930s and quite damp but again was not an issue previously. Any ideas?

 

[Nige F]

must be a musty West Country thing