A high-rise tower that was gutted when a blaze tore through it on Tuesday night was covered with cladding that was banned on new buildings three years ago.
Sharjah's Abbco Tower was built in 2005 with an external material that was widely used in the Emirates until it was prohibited in January 2017.
Flames spread up and around the 48-storey building in minutes after it was first reported about 9pm.
It took several fire crews about three hours to bring the blaze under control, as debris rained down on parked vehicles.
Despite the intensity of the blaze, hundreds of residents escaped quickly, running down fire escapes in the 190-metre tower, one of Sharjah's tallest. Fire alarms that sounded in more than 300 apartments were credited with saving lives and only seven people were injured.
“The fire spread faster because of the cladding," Col Sami Al Naqbi, head of Sharjah Civil Defence, said.
"Since the building is somewhat old, it was installed with the cladding before it was banned."
Brig Ahmed Al Serkal, head of the forensic laboratory at Sharjah Police, said government officials were meeting to look at how widely the cladding was used and if it could be removed from towers built pre-2017.
"Cladding helps to spread fire from one floor to the other very fast," he said.
He said the cause was being investigated.
“For us to give the accurate cause of fire, our experts still need to examine the place, after firefighters search the building flat by flat to make sure no one was left behind,” he said.
The material is a form of aluminium composite panel cladding and was widely used during the UAE's construction boom.
It was a factor in several fires including The Torch and Zen Tower in Dubai Marina, the Address Downtown and the Adriatic building on the Palm Jumeirah. In all four buildings it was replaced during extension renovation.
The cladding, which gives buildings a sleek modern look and was cheap and easy to install, was also used on London's Grenfell Tower, in which 72 people died when a fire gutted the building in June 2017.
Grenfell was built in the early 1970s but fitted with cladding during a renovation in 2015-16 to improve energy efficiency and give it a fresher look.
Aluminium composite panel cladding was prohibited in UAE when the country's Fire and Life Safety Code of Practice was updated in 2016. It was made public in January 2017.
Builders must now use more expensive non-combustible cladding that better halts the spread of flames, but the authorities have not ordered that older buildings be retrofitted.
Andy Dean, head of facades at engineering firm WSP's Middle East office, said the industry was well are of the safety issues cladding poses.
"The problem was there was a lack of knowledge about façade cladding and there was no coupling between the fire and façade industries until 2012," he said, the same year Tamweel Tower in Dubai's Jumeirah Lakes Towers was left uninhabitable by a huge fire, and when the first update to the safety code began to tighten building regulations.
"People thought they were doing the right thing by using them. They are a low cost material that is high performing and durable."
The cost involved of stripping cladding from a building would be in the millions - Zen Tower's reconstruction and cladding removal was Dh25 million - but he said many companies were willing to face the problem.
"Retro fitting is absolutely feasible, it’s been happening here for at least five years or more," Mr Dean said.
"It’s not uncommon for the big developers to ask us “'can you tell me if my building is a problem?'”
"But it’s difficult and hugely expensive to take an entire façade off a building and replace it."
If full-scale renovation of a building is not possible, engineers may look at fire breaks - flame-proof barriers installed every 10 to 20 metres.
In many cases, he said safety could be improved significantly by ensuring sprinklers were installed and working and that alarm systems are up to date.
"A large part of the existing building stock has a problem and that can’t be ignored," he said.
"Things are changing here though, buildings are dramatically safer than years ago because of the introduction of the 2012 fire safety code."