Non-standard construction
A BISF house is named and the roof truss was only seen from the hatch. What of the steel frame upstairs was not inspected?
The steel frame of the upper storey, beyond what a hatch can show, was not inspected. A BISF house is a steel-framed system. From the hatch the survey could see a limited part of the roof structure. It could not see the stanchions in the upstairs walls, the connections hidden by linings, or corrosion behind cladding. Those parts of the frame were not inspected. The name BISF is not a claim that the whole upstairs frame was examined. The unseen steel stays unseen.
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?
BISF frames carry the house in steel, with cladding that often hides the members. A roof truss at a hatch is a timber or steel piece in the roof void, not a tour of every stanchion. Linings, bedrooms and replacement cladding block the view. The survey can name the system from what it had a basis to name, and still list a limit at the hatch. The mechanism is concealment. The frame upstairs was not opened up, so its condition is not a finding.
Tell the solicitor the house is described as BISF and that the upstairs frame was not inspected beyond the hatch view. A lender may have its own view of steel-framed houses. That is the lender's rule, not a result this visit measured. If you need the hidden steel assessed, a specialist who understands this system can advise what opening-up is useful. The survey has not done that opening and has not graded the unseen members.
What should you ask your surveyor?
- What of the frame was actually visible from the hatch?
- Is the cladding original or a later skin over the steel?
- Which upstairs members does the limit say were not seen?
What are the typical next steps?
- Tell the solicitor the upstairs steel frame was not inspected beyond the hatch.
- Do not describe unseen stanchions as sound.
- Ask the lender what they require for a BISF house, as their own rule.
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 new brick cladding make the steel frame irrelevant?
No. New cladding can hide the frame. It does not remove it, and it does not mean the hatch view inspected the upstairs steel. The survey named a BISF house and saw the roof truss from the hatch only. Members behind the new skin were not inspected. Cladding is a covering. The frame is still the structure the limit applies to.
Is a BISF house the same system as a concrete panel house?
No. BISF is a steel-framed system. Concrete panel systems are a different form of non-standard construction. The survey has named BISF and has not reclassified the house as concrete. The limit remains the one in the question: the roof truss was only seen from the hatch, so the upstairs steel frame beyond that view was not inspected.