RAAC

Does seeing the flat roof of a 1970s school conversion from a hatch identify RAAC?

No. A hatch shows whatever was visible, such as felt, timber, a deck or a soffit, and that view does not by itself identify reinforced autoclaved aerated concrete. The Institution of Structural Engineers says RAAC has been used since the late 1950s, most commonly as precast flat-roof panels. Age and a flat roof are why you ask, not the identification.

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?

Former schools are where buyers now expect the word. Expecting it is not seeing it. IStructE’s route, where the construction is unclear, is to have it inspected, and where RAAC planks are present a chartered or incorporated structural engineer determines their condition. A home survey is visual. It does not complete that assessment. If the hatch showed timber, say timber. If it showed a concrete soffit the surveyor could not name, say it was not identified.

Do not tell a lender the roof is RAAC because the building was a school in the 1970s. Do not tell them it is clear because you dislike the question. The RICS consumer guide says survey cost is variable and that there is no national tariff. It is not a RAAC fee. An engineer, if one is needed, is a separate instruction. Do not invent a fee, and do not add a failure figure the report did not contain.

What should you ask your surveyor?

What did the hatch actually show?
Are you saying RAAC, or that the deck was not identified?
If you suspect RAAC, are you referring it to a structural engineer?

What are the typical next steps?

Use the survey’s words. Do not add RAAC because the building was a school.
If RAAC is suspected, instruct a chartered or incorporated structural engineer, as IStructE advises.
Do not invent a fee.

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

Is every flat roof on a converted school RAAC?

No. Timber and other concrete decks exist. The hatch has to show what this one is, or the report has to say it could not tell.

Does a failed felt prove the deck is RAAC?

No. The covering and the deck are different. Failed felt is a covering defect until the deck is identified.