Wall ties and cavity insulation
Why might wire ties in an early cavity wall corrode while the brick face still looks fair?
Early cavity ties are often thin metal. They can rust where they cross a damp cavity, and the outer leaf can start to move before the bricks themselves look damaged. A fair face is not a certificate that the ties are sound.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Houses with cavities from the early twentieth century were tied in more than one way. Some ties were galvanised and last. Some were light wire and corrode, especially if the cavity is wet or has been filled later. The surveyor cannot see the metal without opening the wall. They can see the symptoms: cracking along bed joints, separation at window frames, or a leaf that is no longer plumb.
Do not decide from the year on the particulars. Ask the surveyor what they saw, not what the decade “usually” does. A specialist inspection is the way to see the metal. Replacement, if it is needed, is a specified job with its own quote. There is no official price per tie that belongs in this answer.
What should you ask your surveyor?
- What symptoms did you see, as distinct from the age of the house?
- Is the outer leaf plumb, or is it bulging between openings?
- Would a Level 2 be expected to see the ties themselves? It would not.
What are the typical next steps?
- If there are no cracks and no bulge, do not invent a tie failure from the year of construction.
- If there are cracks in the bed joints, ask for a cavity inspection before you negotiate a figure.
- Tell the specialist if the cavity has been insulated. Insulation changes what they can see.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Are fishtail ties the same as wire ties?
No. They are different shapes and thicknesses. The specialist should name what they find. The home survey often cannot.
Does a rendered wall hide tie failure?
Render hides the brick joints. Cracks in the render can still follow the lines of the ties. Hidden does not mean absent, and it does not mean present.