How did cladding from five Norwich tower blocks with a top fire safety rating fail tests?

That is the question being asked by the blocks' developer Taylor Wimpey, the MP and one of the landlords.

The tests were carried out for the Department for Communities and Local Government (DCLG) by the Building Research Establishment (BRE) on a sample of cladding from Brennan Bank on Norwich's Geoffrey Watling Way.

The DCLG ordered the tests after the Grenfell Tower fire on June 14 in which at least 79 people died or are missing.

MORE: Company which installed cladding on Grenfell Tower also clad council office block in Norwich

The cladding at Grenfell was criticised because a product called Reynobond PE was used instead of a fire-resistant alternative called Reynobond FR which was an extra £2 per square metre.

The five new-build Norwich blocks comply with building regulations as the cladding used, called Larson PE, has a top fire safety rating of 'zero'.

But the Larson PE has a polyethylene centre rather than a fire resistant one, which could explain why it failed the tests. A similar product with a fire resistant core is available called Larson FR.

MORE: Cladding on at least five Norwich tower blocks fail fire safety tests

But Andrew Savage, director at Broadland Housing, the landlords at Brennan Bank, said they had no concerns that Larson PE was used by developers instead of the fire-resistant version.

'It is a top class product. It is used all over the world,' he said. And he said they were seeking clarification from the DCLG about what tests were carried out on the cladding samples.

Mr Savage added: 'If the DCLG said 'you must remove that cladding' we will turn around and say why? From the knowledge we have at the moment there is no reason to. The fire officer is saying that building is fine.'

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Norwich South MP Clive Lewis, who visited Brennan Bank on Monday, said he would write to the DCLG to get more clarity. 'At the moment the testing and the methods are rather confusing,' he said.

Norfolk County Council said it had looked at fire safety on three buildings where it had offices with aluminium cladding. One of the offices, Vantage House, was clad by the same company which did the cladding at Grenfell, Harley Facades.

Aluminium cladding is also on the newly revamped County Hall in Norwich and Havenbridge House in Great Yarmouth.

A council spokesman said there was no cause for concern in any of their offices.