Thanks. My garage has cavity walls perimeter as it was built as part of the house (I have bedroom above garage on 1st floor) and I was thinking about adding heating to make garage warm inside -- hate putting lots of cloths on in winter while I work with car
Last winter was -8C in Reading area. But I'm worried about corrosion damage to car as road salt will promote corrosion when it thaws, so I abandoned the idea. Perhaps it is better when car stays in cold during winter.