Ever spotted a flat metal shape with a bolt in the middle on the face of an old brick building and wondered what it is? Those are pattress plates, used because many historic masonry walls lacked reliable lateral restraint.
In large Georgian and Victorian brick elevations, floor joists were not always well tied into the outer walls, internal partitions were sometimes lightweight, and long façades could bulge or drift outward with age. Earlier Tudor timber-framed buildings did not need visible plates because their internal frames braced the walls. Pattress plates, paired with tie bars, pull walls back and keep them there. Think of the plate as an oversized washer that spreads the load while the hidden bar provides the pull.
Shapes and names
Pattress plates can be circular, star shaped, square, and many other wonderful designs. Some resemble letters such as S and X. Fleur de lys patterns are also common on decorative examples. You may hear anchor plate, wall washer, star anchor or S‑iron used for the same idea: a plate on the end of a tie bar that restrains the wall.
How they work
A tie connects the bulging wall back to something stiff inside the building. In the traditional arrangement a metal bar passes right through and tightens against pattress plates on the outside face. That spreads the load and clamps the wall back. Alternatively, the tie can terminate at a concealed fixing instead of a visible plate. Two common approaches are:
• tying the outer wall back into a floor or roof joist with a specialist helical or threaded tie, finished with a small made good patch externally; and
• using a grouted “sock” or resin anchor that expands inside a drilled hole and locks into the masonry or a hidden structural element.
Both methods connect the moving wall to something solid without a plate on the far side.
Beyond house façades
Pattress plates and tie bars also appear on structures that need restraint in other settings. They are used to stabilise spandrel walls on masonry arch bridges and are sometimes specified for parts of retaining walls where low bearing pressure on the face is important.
What they are made from
Historically plates were cast iron, with examples in wrought iron and later mild steel. Today you will also see ductile iron and stainless steel used with modern tie systems. The plate spreads the load over the brickwork. The bar provides the tension that keeps the wall where it should be.
Where they were made in the UK
In the eighteenth and nineteenth centuries many towns had iron foundries producing architectural castings, railings and street furniture, and those same pattern shops produced pattress plates. Notable centres included Ironbridge in Shropshire and the Carron works near Falkirk. The tradition continues today with UK makers supplying replacements and conservation‑grade hardware in the classic patterns you still see on historic streets.
How pattress plates differ from buttresses
A buttress is a block of masonry built out from the wall that resists thrust in compression and carries load to the ground. A pattress plate and tie works in tension by pulling the wall back to floors or cross walls inside. Same aim, different mechanics. One props. The other ties.
Should you worry if you see them
Not automatically. Plates usually mean the wall was strengthened at some point, not that failure is imminent. Focus on condition. Red flags include fresh stepped cracks, bulging or out‑of‑plane brickwork, plates that look loose or skewed, and tie bars that are slack or heavily corroded. If anything looks new or active, a structural engineer should review it. If the plates look old and the wall is straight and uncracked, they are normally a sign of past strengthening rather than a live problem.
Survey Shack’s advice
We do not install ties or rebuild walls. We help you read what you are looking at. If you see pattress plates, note their positions and check the brickwork around them. Inside, look near floor levels for cracks or small distortions that line up with the plates outside. If you are refurbishing, take the opportunity to check any accessible tie hardware because some components can be more than two hundred years old. Where there are signs of ongoing movement, we will point you to the right next step so a competent contractor or structural engineer can test, tighten or replace what is needed. The goal is simple. Understand the restraint, read the story the wall is telling, and act on evidence rather than guesswork.
Small glossary for first‑time buyers
Lateral restraint: sideways support to stop a wall leaning out.
Tie bar or tie rod: a long metal bar that pulls a wall back into line.
Pattress plate or anchor plate: the visible metal plate that spreads the load.
Joist: the horizontal timber or steel that carries a floor or roof.
Grouted sock anchor: a hidden fixing that expands inside a drilled hole to lock into the structure.
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