Age and type of house
A workshop conversion has a steel portal the surveyor could see and no calculation was attached. What size of steel was not checked against a design?
The size of the steel portal the surveyor could see was not checked against a design. The workshop conversion has a portal frame in view, so the inspection can say the frame is there and how it looked: rust, connections, and whether anything is obviously bent. No calculation was attached. Section size, span and loading were not compared with a design. Seeing steel is not measuring it against what the conversion asks it to carry. The survey has not produced that check. Approved Document A is structural guidance. It is not a calculation this visit carried out, nor a certificate for the portal.
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?
A portal is a rigid steel frame that holds the roof and the walls of a workshop bay. When it is exposed, a surveyor can describe the member that is in the room. Description is not design. Without a calculation, nobody in this report has said whether the section is the one the span and the new house loads require. A domestic conversion can add ceilings, insulation and rooms the workshop frame was not drawn for. None of that arithmetic was attached to the survey, so the size stays unchecked.
Ask the solicitor for any structural calculation, building-control paper or engineer's drawing for the portal in this conversion. If those papers are missing, a structural engineer can measure the section and check it as a new instruction. Approved Document A does not fill that gap, and the survey has not applied it as a sign-off. Do not tell a lender the steel was designed for the house because it is large and visible. Visible and checked against a design are different sentences.
What should you ask your surveyor?
- Which portal did you see, and what about it was only visual?
- Was any section size checked against a calculation or a drawing?
- Has the survey left the design of this steel unconfirmed?
What are the typical next steps?
- Record the portal as seen, not as checked against a design.
- Ask the solicitor for any calculation for the workshop frame.
- Do not treat Approved Document A as a sign-off of the steel.
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 portal looks heavy, has the size been proved?
No. A heavy look is an impression. No calculation was attached, so the section was not checked against a design. The survey has not measured the steel for the loads of the conversion. Approved Document A is guidance, not that missing calculation.
Does a building-control stamp, if one turns up, replace the survey?
No. A stamp, if the solicitor finds one, is a paper about the work at the time it was signed. It is not this visual note, and it does not rewrite the fact that no calculation was attached to the survey. The survey still has not itself checked the portal size against a design.