A building is an interior, so season and weather don't apply — only the time of day (a night building is warmly lit inside) and the exterior apron.

Building size — rows × columns (each tile is 6″), up to 6×6. Stored as the first two letters of the code (A=1, C=3, F=6), so CC… is 3×3.

Exits — leave blank for the default (about a third of the perimeter walls), or pin an exact number of door exits (Xnn), clamped to the number of perimeter cells.