RAAC

If the felt on a flat roof has failed, does that mean the RAAC underneath has failed too?

No. The covering keeps the water out. The panels, if they are RAAC, are the structure. Both can be wrong, or only the felt can be wrong. IStructE’s assessment is about the panels. A roofer’s view of the felt is about the covering. A home survey may see ponding and a stained soffit and still not have assessed either properly.

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?

Water is relevant to both. A failed covering can load and stain panels. That does not identify the panel as RAAC and does not grade it. If the surveyor has named RAAC and also rated the covering, keep both recommendations: an engineer for the panels, a roofer for the waterproofing, in that order if the structure is in doubt. Overlaying felt on a panel an engineer has not seen can hide the problem IStructE wants assessed.

If the surveyor has not named RAAC and has only rated the felt, do not add RAAC because flat roofs and concrete are in the news. Ask what the deck is. Ordinary failures of felt are common and have their own repairs. There is no IStructE or RICS combined price for “felt plus RAAC”. Get the right reports.

What should you ask your surveyor?

Have you identified the deck, or only the covering?
Is the soffit stained, cracked, or not seen?
Which specialist do you want first?

What are the typical next steps?

Do not overlay the roof until you know the deck.
If RAAC is suspected, engineer first.
If the deck is timber and the felt has failed, the roofer is the right next call.

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

Can you live under a stained soffit while you wait?

If the surveyor or an engineer has said it is unsafe, do not. If they have only seen an old felt failure and no panel concern, follow that wording. This page cannot clear a roof.

Does ponding prove the panels have crept?

Ponding proves the falls are poor or the covering has sagged. Deflection of panels is an engineer’s measurement. Do not equate the two.