Non-standard construction
Can a brick outer leaf hide a steel or concrete frame from a visual survey?
Yes. Brick, stone and render are claddings. They can sit in front of a frame or a concrete panel the surveyor never sees, unless a junction, a loft or a meter cupboard gives the construction away. A house that looks like a cavity semi from the street may not be one. The report should say how the construction was identified and where it is only assumed.
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?
RICS home surveys describe construction from what is visible and from experience of building types. They do not core every wall. If the surveyor writes “assumed cavity brickwork” they are telling you it is an assumption. That word matters when a lender later asks for the construction. If they write “concrete panels behind render” they are raising a non-standard system. Both sentences are more useful than a silent assumption.
Where the construction is only assumed, and the house is of an age or a form that might be a system, ask the question before the mortgage application says “standard”. Opening up is a further instruction. Do it with the seller’s consent, in a place that can be made good, and only if the answer changes the purchase. There is no point coring a wall the loft already explains.
What should you ask your surveyor?
- Where did you confirm the construction, and where have you assumed it?
- Is there any sign of a frame, panels or a system roof?
- What single opening, if any, would confirm it?
What are the typical next steps?
- Read the construction paragraph before you fill in the mortgage form.
- If it says assumed, ask the surveyor what else is possible.
- Do not core the wall on a viewing.
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 pattern of brick ties prove a traditional cavity?
It suggests two leaves of masonry. It does not prove what the inner leaf is made of if nobody has seen it. Ask.
Can the loft show the inner leaf?
Often the gable in the loft is the best view. If the loft was not entered, that evidence was missed. Read the limitations.