Building control officers responsible for signing off the proposals to overclad Grenfell Tower as part of its ill-fated refurbishment did not understand the difference between cavity barriers and firestopping, Studio E Architects’ project lead has said.

On his last day of evidence to the Grenfell Inquiry, Neil Crawford related “frustrating” exchanges with Kensington and Chelsea council’s building control officers over plans to limit the spread of fire between the original concrete exterior and the new envelope proposed for the 24-storey block.

Crawford said in his written witness statement to the inquiry that there was a lack of clarity on the part of officers John Hoban and Paul Hanson over proposals for cavity barriers – to stop fire spreading in the cavity between the cladding and original concrete panels of Grenfell Tower – and firestops. The latter would be required to stop fire spreading between floors or through openings in fire-rated walls.

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