RAAC

Nothing on the visit sampled RAAC guidance aimed at larger buildings, opened a house extension or tested a reason to skip a plank that looks like the material. What has to stay undecided?

There is no reason, from this visit, to skip a plank that looks like the material just because some RAAC guidance is aimed at larger buildings. The survey has not sampled the plank in the house extension, and it has not tested a reason to ignore it. RAAC is a form of concrete panel that IStructE says needs investigation. Guidance written for schools or other large buildings does not identify this plank and does not clear it. Whether the extension contains that material stays undecided.

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?

Attention has focused on roofs and floors in bigger public buildings. A house extension can still contain a concrete plank that looks similar. Looks are not a sample. The home survey can record the soffit, the span and the suspicion. It cannot say the domestic setting makes investigation unnecessary, and it cannot say the plank is RAAC. IStructE's point is investigation where the material is suspected. The scale of the building in a guidance note is not a test of this plank, and this visit did not perform one.

Tell the solicitor the extension plank is suspected, not identified, and that larger-building guidance was not a reason to skip it. If investigation is needed, instruct someone asked to investigate that form of concrete panel, and do not ask the home survey to sample it after the event. Do not dismiss the note because the house is not a school. The survey has left the material undecided on purpose. Keep it undecided until an investigation says what the plank is.

What should you ask your surveyor?

What did the extension plank look like, and where is it?
Was any sample taken, or only a visual suspicion recorded?
Is larger-building guidance being used as a reason to ignore it?

What are the typical next steps?

Do not skip the plank because guidance mentions larger buildings.
Treat the material as not yet investigated.
Instruct a proper investigation if the suspicion needs resolving.

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

Was the extension plank sampled?

No. Nothing on the visit sampled it. The survey has not investigated the plank. RAAC is a form of concrete panel that IStructE says needs investigation. A resemblance is not that investigation. What the plank is made of stays undecided.

Does looking like the material decide what it is?

No. Appearance prompted the note. It does not identify RAAC, and it does not clear the plank. Guidance aimed at larger buildings was not a test of this house extension and is not a reason to skip it. Identification waits on an investigation that has not happened.