What is a masonry offset?
A masonry offset is a place where brickwork steps back in stages, so that the wall or foundation has a larger cross-section at the bottom than at the top. In Dutch it is called a versnijding. By letting the thickness increase towards the bottom, the load is spread over a larger area and the structure becomes more stable.
Where do you see masonry offsets?
- Brick spread foundations: the foot of the wall widens towards the bottom. Every few courses, the brickwork steps out by about a closer (a quarter brick) on either side, so the foundation widens in steps. Such a stepped foot is also called a stepped footing.
- Buttresses: a buttress projects further from the wall at the bottom than at the top, with sloping or stepped offsets.
- Towers, churches and tall walls: the wall becomes thinner with each storey. On the outside you see a set-back ledge, often covered with a sloping weathering or zinc capping.
A transition from a square to a round or octagonal upper structure, as with a squinch, is not called an offset but has its own Dutch term.
Second meaning
The Dutch verb also means mixing in a cheaper substance to obtain a larger quantity, such as cutting paint or bitumen with a filler. This is also where the Dutch word for cutting waste comes from.
Tips for old buildings
- Water run-off on the offset: a set-back part of a wall is a horizontal surface where rain lies. Check that the capping (lead, zinc, natural stone or a sloping finished layer) is intact and falls to the outside.
- Foundation repair: when exposing an old brick foundation, you will see the offsets. Do not damage the bottom courses when digging; they carry the load.
- Do not confuse with corbelling: with corbelling, the brickwork projects further out towards the top instead.
Related terms
- Foundation
- Buttress
- Closer (queen closer)
- Corbelling
- Tapering a wall
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