Wall ties and cavity insulation
Fishtail ties are named for an Edwardian cavity that was not opened. What is that name based on?
The fishtail name is not based on a tie seen in an opened cavity. The wall was not opened, so no tie was taken out or photographed in place. Fishtail ties are a traditional shape linked with walls of that age. Here the name is an inference from the Edwardian construction, not a finding from a seen tie. The survey has not confirmed the metal or that fishtails are what this cavity holds. The basis is the age of the wall, not an opening.
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?
You only know a tie's shape by seeing it. An unopened cavity hides the metal in the bed joint. Walls of this age were often built with fishtail ties, which is why a report can call that the likely type. Likely is not seen. Corrosion and the number of ties stay invisible until the cavity is properly inspected. This visit did not open it. The word is a label from context. It is not a retrieved tie.
Tell the solicitor the ties were named without the cavity being opened, so the type is inferred. If condition matters, a specialist can inspect the ties properly. The survey has not done that and has not said the ties have failed or passed. Do not tell a lender the wall contains sound fishtail ties. They were not seen. Read any certificate for the elevations it actually names.
What should you ask your surveyor?
- Was any joint opened on this wall?
- Is the fishtail wording given as seen, or as likely for the age?
- What inspection would show the tie itself?
What are the typical next steps?
- Treat the fishtail name as an inference from an unopened wall.
- Do not tell the lender the ties were seen and passed.
- Ask a specialist if the cavity ties need a proper inspection.
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
Does the Edwardian date prove the ties are still sound?
No. The date is why a fishtail type might be inferred. It says nothing about corrosion or about whether the ties still work. The cavity was not opened, so condition was not seen. The survey has not passed the ties and has not failed them. Age is context for the name. It is not a test.
Was a tie removed and kept?
No. The cavity was not opened, so no tie was removed and none was kept. The fishtail name is not based on a sample. There is nothing from inside the wall to show a specialist later. If ties are to be sampled, that is a further inspection. This visit ended without one.