Wall ties and cavity insulation
How should a buyer separate a boot lintel, rust at the toe and the cavity the rust stain does not open when all three are mentioned together?
Separate the lintel shape, the stain and the closed cavity. A boot lintel is a concrete lintel with a toe that projects over the outer leaf. Rust at that toe is a stain the survey could see. The cavity behind the stain was not opened, so the stain does not show whether a steel edge, a tie, a tray or the concrete itself is involved. The report records shape and stain. It has not tested ties and it has not diagnosed the rust.
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?
Boot lintels often have a steel angle or a reinforced toe, and corrosion there can crack the concrete nib that shows outside. A brown stain can also track from a rusty tie, a steel beam further in, or iron fixings, and those sources sit in the cavity the stain does not open. This visit did not open the toe and did not look behind the leaf. The pattern is a prompt. It is not a section through the wall.
Ask the solicitor whether any lintel replacement, cavity-tray work or tie report already covers this opening. A specialist can open the cavity or the toe if the cause has to be known. Tell a lender the boot pattern and the rust were seen and the cavity was not opened. Do not brief a builder to price a particular repair as if the survey had chosen between lintel, tie and tray. It has not.
What should you ask your surveyor?
- Was rust at the boot toe only seen from outside?
- Did the stain open the cavity, or was the cavity left closed?
- Have ties, tray and lintel steel been left undistinguished?
What are the typical next steps?
- Keep the boot lintel, the toe rust and the unopened cavity apart.
- Ask the solicitor for any lintel or tie papers for this opening.
- Do not price one repair as if the cause were already chosen.
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 a boot lintel mean every window in the house is the same?
No. One opening can have a boot lintel while others have timber, steel or a different concrete section. The survey described the lintel it was writing about, with rust at the toe. It did not open every head and did not test ties. Do not copy this stain across the elevation without looking.
Is the rust a wall-tie failure by definition?
No. Rust at the toe of a boot lintel can come from the lintel itself. A tie failure is a cavity question, and this stain did not open the cavity. The survey did not test ties. Treat tie corrosion as unproved unless a separate investigation sees the ties. The visible rust is not that investigation.