An anchor plate — also called a wall anchor or, in its bar form, a tie bar — is a wrought-iron or steel fitting that ties the timber floor structure to the external wall, so the facade cannot bow outwards. The visible part on the facade — the scroll, the S-shape, the plain bar or the date figure — is only half the story; behind the masonry sits the actual connection to the beam.
Masonry is strong in compression but takes no tension. A tall, slender facade with no connection to the floors will bow outwards over time, especially under wind pressure or the spread of a roof structure. The anchor ties facade and floor structure into a single whole.
How it works
The classic arrangement has two parts. At the beam end sits a wrought-iron strap or rod that passes through the wall and emerges outside with a slot or eye in it. Through that slot a pin is dropped on the outside: a cross bar that bears against the masonry and holds everything in place. If the facade moves outwards, it pulls against the pin and therefore against the beam.
The pin is what you see from the street. Common forms:
- Straight pin, a simple bar — the most common by far
- S-anchor or scroll anchor, decoratively forged
- Date anchor, where the pins are shaped as numerals and together spell the year of construction
- Letter anchor, with initials or a symbol
Maintenance and points to watch
- Corrosion is the main risk. Rusting iron expands to several times its original volume, and that splits the surrounding masonry — recognisable by hairline cracks radiating from the anchor and by pushed-out joints
- Never simply remove one. An anchor plate is a structural component. If it is loose or distorted, first have it assessed whether the facade stays tied
- Repair rather than replace. On a listed building a corroded anchor is normally de-rusted, treated and refitted; replacement in stainless steel is reserved for severe section loss
- Check the beam end. Where an anchor rusts, moisture has usually reached the beam end too. On finding anchor damage, always inspect the timber inside
- New build works differently. There you find no visible anchor plates but stainless wall ties between the outer and inner leaf, plus a tie between the floor and the inner leaf
- Painting helps. A well-maintained paint film on a historic wrought-iron anchor lasts for years and prevents damage to the masonry
Related terms
- Wall tie
- Beam end
- Floor structure
- Summer beam
- Masonry
- Tie bar
- Listed building
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