Wall ties and cavity insulation
Why do surveyors treat cavity-wall ties near the coast with extra caution?
Salt air and driving rain keep the outer leaf wetter, and wetter mortar is harder on metal ties. A fair brick face in a sheltered street is not the same evidence as a fair face on an exposed seafront. The survey still cannot see the ties unless someone looks into the cavity.
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?
The caution is about risk, not about a rule that every coastal house needs new ties. Horizontal cracking, lifted courses and previous tie replacement still matter more than the postcode. A visual survey records exposure and those signs. It does not measure salt in the mortar and it does not extract a tie as a sample unless that extra was agreed.
If you insulate, the Energy Saving Trust says walls exposed to driving rain are a poor candidate for cavity fill, and that exterior repairs should come first. That is an insulation warning, not a diagnosis that the ties have failed. Keep the two questions apart when you speak to a lender or an installer.
What should you ask your surveyor?
- What signs of tie failure did you see, as against general exposure?
- Is this wall one you would fill, given driving rain?
- What would a borescope add that the view from the ground does not?
What are the typical next steps?
- Do not buy a coastal tie replacement package on the postcode alone.
- If there are regular horizontal cracks, ask for an inspection that will see the ties before you exchange, if the loan depends on it.
- Repair pointing and gutters before anyone talks about filling the cavity.
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
Is a mile inland “coastal” in this sense?
Exposure is about the site and the wall, not a line on a map the survey has not drawn. Ask what this elevation is like in driving rain.
Does new pointing prove the ties are new?
No. Pointing hides the joints. It can also hide the holes where ties were replaced, or hide cracks. Ask what the pointing is covering.