Boulin

A boulin is a type of scaffolding hole, specifically a hole left in a wall for supporting scaffolding during construction. These holes are typically horizontal and of a size appropriate for receiving a wooden beam or pole (the boulin itself) which then forms part of the scaffold's framework.

After construction, boulin holes are usually filled, but sometimes they are left unfilled or are filled in a way that leaves a visible mark. These marks can often be seen on older buildings and provide evidence of past construction or renovation. Different regions and eras might have used different techniques for filling boulin holes, resulting in variations in the appearance of the repairs. The presence and pattern of boulin holes can sometimes offer clues about the building's construction history, the type of scaffolding used, and even the age of the structure.