External levels should be resolved on the drawing
Patios and paths often rise over time. The damp-proof course and threshold need enough separation from finished ground while still giving usable access.
Openings need proper cavity closure
Doors and windows interrupt the wall cavity. Closers, trays and insulation around reveals have to manage both water and heat loss.
Roof abutments need more than visible flashing
Where a roof meets an existing wall, cavity trays and internal construction can matter as much as the lead or membrane visible outside.