We are about to convert our integral garage which is mostly underground (house built into a slope). Building regs noticed that there was moisture in the cavity (he was looking for insulation and found that the poly beads in the cavity were damp) and have suggested a membrane, then build effectively a stud wall with kingspan attached so that there is a 1" gap between wall and new partition (then 3" kingspan).
I'm concerned about where the moisture goes once a membrane is put in place - is it assumed that it will evaporate and head upwards, in which case do I need to worry about my ceiling and floorboards above (our living room is above the garage)?
Also, should I be concerned about the moisture in the cavity, I dont know how our garage and basement (behind it) are tanked but perhaps moisture in the cavity is normal for underground structures (?)
thanks
J