Does it look damp? flakeing paint, peeling wallpaper or mould. A dpc is unlikely to fail, most of the time dampness is caused by the dpc being bridged by debris and dirt in the cavity
Two weeks stopped at the moment, got some pills off the doc called champix and am finding it 100% easier than i thought it would be, no cravings at all after 40 years on the weed.
good luck whatever you try