Basic - Wood, Lathe & Plaster, Wattle & Daub, Adobe, Sun Dried Bricks. Basic building materials are used for the majority of buildings. They have thatched or shingle roofs, ordinary doors and light shutters at the windows. These building cannot be fortified (Except for Palisades)

Stone - this includes normal field stone, cobbles, kiln fires bricks, etc. The building might be timber framed and might have a slate roof. They might have strong doors, good locks and strong shutters at the windows.

Fortified - Stone buildings that have been strengthened with extra layers of stone, and earth embankments. The stone is often smooth, to make it more difficult to climb. Fortified building have iron bound doors and shutters, and generally have arrow slits instead of windows.