Arup fire engineer Barbara Lane has criticised building regulations for not having a “Plan B” should its fire systems fail.
Lane told the Grenfell Tower Inquiry how there was no alternative plan for firefighting and evacuation when the compartmentation system of keeping fire contained within one flat failed.
She outlined how no provision was made in the Building Regulations 2010, or design and construction at the tower, for an alternative fire safety system to compartmentation.
Lane gave evidence to the inquiry as housing secretary James Brokenshire launched an eight-week consultation on whether the government should ban combustible cladding on high-rise residential buildings (18m tall or more).
Compartmentation works by using fireproof walls, floors and doors to keep a fire contained within one flat. The flammable material used in Grenfell Tower’s cladding system let the fire spread quickly across the building envelope, meaning compartmentation failed.
Lane said: “I consider the building’s ‘stay put’ strategy to have failed at 1.26am, and that all events after that time occurred in the total loss of the only safety condition provided for.”
There is no requirement in the Building Regulations 2010 or Approved Document B, the government’s advice on how to comply with building regulations, to provide for a total building evacuation.
Instead, active and passive firestopping methods – such as fireproof walls and doors, filling gaps around pipes to stop flames and smoke spreading, and smoke ventilation systems in the lobbies – are relied on to keep fire contained within one flat and on one floor.
Under a “stay put” strategy, residents are supposed to stay in their flats while the fire service extinguishes a single flat fire.
There was no provision in the tower’s design for firefighters to tackle an external fire, nor was there a whole-building alarm system to tell residents to evacuate.
As a result, Lane said an “external fire scenario not happening is critical to maintaining this box [of compartmentation] around each flat”.
She said: “The ‘stay put’ strategy is provided through design, construction and ongoing maintenance. All building occupants, including the fire brigade, rely on it in the event of a fire.
“It is the single safety condition provided for in the design of high-rise residential buildings in England. The statutory guidance makes no provision within the building for anything other than a stay put strategy.”
Combustible cladding provided an easy route for fire to spread between flats, while fire doors leading to the tower’s single staircase only resisted fire for 20 minutes, less than required in the building regulations.
Lane said: “Faulty fire doors mean faulty compartmentation, and compartmentation is the primary basis of the stay put strategy.”
She also stressed the gas pipe replacement works ongoing when the fire occurred had left a pipe running through several floors with “incomplete compartmentation works and incomplete ventilation works on the night of the fire”.
Lane’s comments came as Ministry of Communities, Housing and Local Government (MCHLG) secretary James Brokenshire launched a consultation on banning combustible cladding on high-rise residential buildings.
Dame Judith Hackitt, chair of the building regulations review, was criticised last month when her final report did not recommend a total ban on combustible cladding.
Brokenshire said: “I have listened carefully to concerns and I intend to ban the use of combustible materials on the external walls of high-rise residential buildings, subject to consultation.
“The cladding believed to have been used on Grenfell Tower was unlawful under existing building regulations. It should not have been used. But I believe that the changes on which we are consulting will offer even greater certainty to concerned residents and to the construction industry.”
The consultation runs until 14 August.