A putlog hole is an opening in masonry through which a putlog passed. A putlog is the short transverse member of a scaffold that carries the working platform. In historic building practice — and with a putlog scaffold to this day — one end of that member bore directly on the wall itself. The hole left open for it is the putlog hole.
Why it is there
Masonry has to rise together with the scaffold. On a wall built from the outside, the scaffold needs a stable platform at every working height. Rather than erect a fully independent scaffold, the bricklayer simply left out a brick at regular intervals. The putlog went into the gap, bore on the masonry, and the scaffold had its second support without any extra material.
Putlog holes therefore appear in a recognisable pattern: in horizontal rows, at fairly regular spacing, each at the height where the bricklayer needed a new lift of scaffold.
What the filling tells you
Once the work was complete the holes were filled in — usually with whatever brick was to hand, and often in a slightly different mortar or colour. That is precisely why they remain visible in old masonry. Sometimes they were deliberately left open, for future maintenance or as nesting places for pigeons and bats.
Value in building archaeology
For historic building research, putlog holes are valuable evidence:
- The height of the rows shows in which lifts a wall was built. Where work paused, the pattern stops or steps.
- A deviating row points to a later alteration, a raising or an added section.
- They reveal the sequence of construction of wall sections that appear seamless from outside.
Practical points
- Do not simply fill them during restoration. Record the pattern first; it is often the only surviving evidence of the building sequence.
- Moisture and frost. Poorly filled putlog holes are weak points: they absorb rainwater and spall in frost. Fill them with a mortar matched to the existing work in strength and vapour permeability — not a strong cement mortar in soft historic masonry.
- Nesting sites. Open holes in old masonry are regularly occupied by protected species. Have this checked before closing them up.
Related terms
- Bond pattern
- Brick
- Scaffolding
- Piecing in
- Building archaeology
- Building fragment
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