LONDON (Reuters) - The cladding system used on London's Grenfell Tower would only have met British regulatory standards if the two main materials had passed a key safety test together, according to a Reuters analysis of the building code and data on the materials.
Three weeks after the June 14 fire, neither the twocompanies involved in the cladding on the Grenfell Tower nor the local authority which enforces the building codes have addressed questions from Reuters about whether that test was ever conducted and its outcome.
The test is required to show whether both materials when used together were sufficiently resistant to combustion. Without proof that it had been carried out, the cladding system would not have met building regulations.
The cladding work carried about by Rydon Group Ltd, the maincontractor on the 2014-2016 refurbishment of the building, andits subcontractor Harley Facades involved attaching insulationboards to the tower's concrete facade and covering them withaluminum composite panels
. France's Saint Gobain said the insulation used was its brandof polyisocyanurate (PIR) called Celotex RS5000.
The aluminum panels, which had a polyethylene plastic corewere called Reynobond PE, and made by New York-based ArconicInc, previously known as Alcoa Inc. If all the elements of the insulation system had achieved aseparate and demanding government standard called "limitedcombustibility", in separate tests, then a combined test wouldnot have been necessary, according to the building regulations.
But Reynobond PE and Celotex did not meet the combustibility test by themselves, according to safety experts and product specifications published by the manufacturers.
This meant that the two materials combined would need topass another test known as the BS 8414 test, according to thebuilding regulations. This involves setting a fire under athree-storey mock-up of the proposed wall construction.
Both standards, set out in the guidelines to the buildingcode, aim to prevent a fire spreading quickly from inside and upthe exterior walls, something that happened at Grenfell Tower.
In a June 29 email, a spokeswoman for Rydon Group Ltd saysit “met all building regulations” but did not say if the BS 8414test stipulated in the building codes had been conducted.
The building control department of the local Royal Boroughof Kensington and Chelsea council (RBKC), which is responsiblefor checking that the building and plans are consistent withregulations, declined to say if it had checked the tests hadbeen carried out.
Police think the cladding system at Grenfell Tower may havecontributed to the rapid spread of last month's fatal fire. Theyhave said they are investigating possible criminal behavior andthe role of all the companies involved in the building.
The Department for Communities and Local Government, thegovernment department which is responsible for setting theregulations enforced by building control, has said the claddingsystem used at Grenfell did not comply with the building rulesit oversees. It has not said why and declined to answer detailedquestions on its legal reasoning. Link to graphic of Grenfell Tower cladding system:tmsnrt.rs/2t97Ugs
The test used to assess combined materials must becommissioned from a government approved independent testingagency. Reuters was unable to determine which, if any lab wasused.
Rydon, which had a turnover of 249 million pounds last year, told Reuters the materials it used were suitable for use in tall buildings. “Laboratory testing of the fire resistance of the claddingsystem used at Grenfell Tower was carried out prior toinstallation. Please see attached BBA certificate,” the spokeswoman said in the June 29 email.
The certificate Rydon provided showed the panels met aseparate standard on the surface spread of fire.
Asked specifically about the BS 8414 test, the Rydonspokeswoman said: “More technical questions would be betterdirected at Harley as it’s their area of expertise.”
Executives and a spokesman at Harley, a small company with few assets, declined to comment for this story. It said in a statement on its website last month it was not aware of any link between the fire and the exterior cladding to the tower.
An official at RBKC, the Royal Borough of Kensington andChelsea, declined to provide details of the specification itapproved or what checks it conducted to ensure the actualconstruction met the approved plan, citing the ongoing policeinvestigation into the fire.
A spokeswoman for Saint Gobain said its BR 135combustibility certification of Celotex was based on testsconducted with a non-combustible cement façade panel. Shedeclined to say if Celotex had ever passed the BS 8414 test witha flammable façade panel such as Reynobond PE.
Editing by Anna Willard