How practical and buildable a design actually is in the real world - whether a detail can physically be assembled in the sequence intended, whether a component can fit through the access route it needs to reach its final position, whether the design assumes tolerances the trades on site can actually achieve. A formal Constructability Review brings contractor and trade expertise into the design process early, specifically to catch these problems on screen instead of on site.

Clash detection catches whether two elements physically overlap; constructability review catches the broader, harder question of whether a design that has zero geometric clashes can still actually, practically be built the way it was drawn.