Age and type of house
A mezzanine in a barn conversion is nailed up to a truss the surveyor could see. What structural check of that connection has not been calculated?
The structural check of that nailed connection has not been calculated. A mezzanine in the barn conversion is nailed up to a truss the surveyor could see, so the inspection has a visual note of nails into a truss, not a calculation of what the connection can carry. Approved Document A is guidance on structure. The survey has not assessed this connection against it and has not produced a structural certificate. Seeing nails does not show the load path, the truss design, or whether the mezzanine was part of the original frame. The check remains uncalculated.
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?
Trusses are designed as frames. Nailing a mezzanine to one changes how loads might enter that frame, and whether the change is acceptable is a calculation, not a photograph. The surveyor could see the connection. They did not analyse timber grades, nail patterns as a designed joint, or the rest of the truss hidden by finishes. A barn conversion often has a paper trail of structural design. The inspection did not replace that trail and did not certify the work. It also did not declare the nails unlawful.
Ask the solicitor for the conversion drawings and any structural design that shows this mezzanine and this truss. If those papers are missing, a structural engineer is the person who can calculate the connection. Do not ask the home survey to invent the numbers. Do not tell a lender the nailed joint was proved because it was visible. Visible is all the survey has established.
What should you ask your surveyor?
- What of the nailed connection did you actually see?
- Did you calculate the load on that truss, or only record the nails?
- Are you issuing any structural certificate for the mezzanine?
What are the typical next steps?
- Treat the nailed connection as seen but not calculated.
- Ask the solicitor for the barn conversion's structural drawings.
- Get an engineer to check the connection if the papers do not.
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
If the nails look new and regular, has the joint been proved?
No. Regular nails are a tidy fixing the surveyor could see. They are not a calculation of what the truss can take. The structural check of that connection has not been done, and the survey has not certified it. A tidy line of nails is still not a designed joint.
Does Approved Document A mean the survey has signed the mezzanine off?
No. Approved Document A is guidance on structure. The survey has not assessed the nailed connection against it and has not produced a certificate. Naming the guidance is not a sign-off of this barn conversion. The barn connection stays uncalculated whatever the guidance is called.