This is a project that entailed replacement of a timber window that had become rotten. The internal cement based plaster was removed, and the area refinished with wood wool board and hemp lime plaster scratch coat and float coat, with a finer top coat lime plaster. Where feasible, we introduced some stud work and sheepswool insulation to reduce potential surface condensation where the wall was thinner in this area. This provided a modest improvement to the energy performance at this area, without going too far with internal wall insulation and risking interstitial condensation. The lime plaster naturally provides an element of vapour control, while the sheepswool also helps regulate humidity, absorbing and releasing water vapour naturally according to conditions.