We are having a new extension built with a lean to roof. The builder has done most of the block work but said he would return to finish the ends once the wall plate had been put on the existing building to build it in and get the line of the rafters. The builder now appears too busy to return and does not return our calls. Should the block work come down in line with the top or bottom of the rafters? Should the cavity be closed along these ends? (Slates have been used along the bottom end) If so should the slates go under the wall plate and noggins used for the gable ladder?