The cladding that might have led to the horrifying blaze at Grenfell Tower was added partly to improve its appearance.

During a refurbishment aimed at regeneration last year, cladding was added to the sides of the building to update its look. The cladding then seems to have helped the fire spread around the building, allowing it to destroy almost the entirety of the structure and kill people inside.

And that cladding – a low-cost way of improving the front of the building – was chosen in part so that the tower would look better when seen from the conservation areas and luxury flats that surround north Kensington, according to planning documents, as well as to insulate it.

Grenfell tower fire Show all 42 1 /42 Grenfell tower fire Grenfell tower fire Local residents watch as Grenfell Tower is engulfed by fire Getty Images Grenfell tower fire London Fire Brigade said there has been a number of fatalities from the blaze Rex Features Grenfell tower fire The fire was first reported in the early hours of Wednesday and continued into the morning Rex Features Grenfell tower fire A local resident sees the fire over the rooftops @Ebajgora Grenfell tower fire A firefighter reacts at the scene of the blaze Getty Images Grenfell tower fire Residents watch as the blaze continues Getty Images Grenfell tower fire More than 200 firefighters have been fighting the blaze PA Grenfell tower fire London Mayor Sadiq Khan has declared the fire a major incident Getty Images Grenfell tower fire Police and fire services attempted to evacuate the concrete block of flats Getty Images Grenfell tower fire A woman runs to assist paramedics working at the fire at the Grenfell Tower Getty Images Grenfell tower fire Smoke rises from the building after a huge fire engulfed the 24 story Grenfell Tower in Latimer Road, West London in the early hours of Wednesday morning Getty Images Grenfell tower fire Fire fighters tackle the 24-storey building in West London Getty Images Grenfell tower fire Ambulances are stationed nearby Getty Images Grenfell tower fire Paramedics arrive with oxygen Getty Images Grenfell tower fire Emergency services believe it will take some time to establish the cause of the fire Grenfell tower fire Tens of people have been taken to five different hospitals across London Getty Images Grenfell tower fire A man comforts a boy after the tower block was severely damaged Reuters Grenfell tower fire Firefighters stand amid debris in a childrens playground nearby Reuters Grenfell tower fire Firefighters are stationed at the building Getty Images Grenfell tower fire Smoke engulfs Grenfell tower Rex Features Grenfell tower fire Lots of people donating water, food and clothing to St Clement's church for the residents of Grenfell Tower in Latimer Road Samuel Osborne Grenfell tower fire A man speaks to a fire fighter after a huge fire engulfed the 24 story Grenfell Tower in Latimer Road, West London Getty Images Grenfell tower fire According to the London Fire Brigade (LFB), 40 fire engines and 200 firefighters are working to put out the blaze. Residents in the tower were evacuated and a number of people were treated for a range of injuries EPA Grenfell tower fire A resident of Grenfell Tower is trapped as smoke billows from the window after a fire engulfed the building Getty Images Grenfell tower fire Members of the emergency services work at the scene of a huge blaze which engulfed Grenfell Tower, a residential tower block in Latimer Road Getty Images Grenfell tower fire According to the London Fire Brigade (LFB), 40 fire engines and 200 firefighters are working to put out the blaze EPA Grenfell tower fire Fire fighters tackle the building after a huge fire engulfed the 24 story Grenfell Tower in Latimer Road, West London Getty Images Grenfell tower fire The burnt facade of Grenfell Tower, the night after the fire in Latimer Road, West London REUTERS/Neil Hall Grenfell tower fire Local residents gather at a community centre near Grenfell Tower in Latimer Road REUTERS/Toby Melville Grenfell tower fire A resident in a nearby building watches smoke rise from Grenfell Tower in Latimer Road, West London AP Grenfell tower fire Police and rescue services operate near the fire at Grenfell Tower, a 24-storey apartment block in Latimer Road EPA Grenfell tower fire A man stands amid debris on the A40 after a serious fire in a tower block at Latimer Road in West London REUTERS/Toby Melville Grenfell tower fire A view of the empty A40 highway after it was closed in both directions, due to the proximity of the fire at Grenfell Tower block in Latimer Road EPA Grenfell tower fire Smoke rises from the building after a huge fire engulfed the 24 storey residential Grenfell Tower block in Latimer Road, West London Getty Images Grenfell tower fire Bodies are removed from the scene after a fire engulfed the 24-storey Grenfell Tower in west London Rick Findler/PA Wire Grenfell tower fire Bodies are removed from the scene after a fire engulfed the 24-storey Grenfell Tower in west London Rick Findler/PA Wire Grenfell tower fire Provisions on tables at the Westway Sports Centre close to the scene after a fire engulfed the 24-storey Grenfell Tower in west London Jack Hardy/PA Grenfell tower fire Beds are laid out in the Westway Sports Centre close to the scene after a fire engulfed the 24-storey Grenfell Tower in west London Jack Hardy/PA Wire Grenfell tower fire A pile of donated clothes, sleeping bags and water lie next to a police cordon near the burning the 24 storey residential Grenfell Tower block in Latimer Road, West London Getty Images Grenfell tower fire Signs asking for donations are seen outside the Notting Hill methodist Chruch Getty Images Grenfell tower fire Smoke rises from the building after a huge fire engulfed the 24 storey residential Grenfell Tower block in Latimer Road, West London Getty Images Grenfell tower fire A man is rescued by fire fighters after a huge fire engulfed the 24 storey residential Grenfell Tower block in Latimer Road, West London Getty

“Due to its height the tower is visible from the adjacent Avondale Conservation Area to the south and the Ladbroke Conservation Area to the east,” a planning document for the regeneration work reads. “The changes to the existing tower will improve its appearance especially when viewed from the surrounding area.”

The document, published in 2014 and providing a full report on the works, makes repeated reference to the “appearance of the area”. That is the justification for the material used on the outside of the building, which has since been claimed to have contributed to the horror.

The materials used were chosen “to accord with the development plan by ensuring that the character and appearance of the area are preserved and living conditions of those living near the development suitably protected,” according to the same report.

A number of conditions were attached to the 2014 decision to approve the plan – many of which related specifically to the material used in the cladding, so that the council could ensure the "living conditions of those living near the development" were "suitably protected".

The council noted that the cladding would also improve insulation, helping keep sound and cold out from the building, and improve ventilation. An environmental statement said that the "primary driver behind the refurbishment" was to address the insulation and air tightness.

"The reclad materials and new windows will represent a significant improvement to the environmental performance of the building and to its physical appearance," the planning application reads. "The design of the scheme as a whole has fully considered policy requirements, expectations and aspirations, fully taking into consideration the immediate and wider surroundings, particularly focussing on creating a wider environment that works as a coherent place," another part of the same document says.

That planning application concludes with a statement that "the development will provide significant improvements to the physical appearance of the Tower, as well as the environmental performance and the amenity of its residents".

Rydon, the company behind the refurbishment work, said the cladding and other changes had been made to help with "improving thermal insulation and modernising the exterior of the building".

Grenfell Tower fire: How the community responded

A statement from Rydon after the work was finished noted that "rain screen cladding, replacement windows and curtain wall façades have been fitted giving the building a fresher, modern look".

That statement included a quote from Nick Paget-Brown, the leader of the council, who remarked on how happy he was to see "first-hand how the cladding has lifted the external appearance of the tower".

That public statement after the completion made no reference to insulation, only discussing the change in the external appearance of the building.

The refurbishment work that added the cladding cost £8.6m and finished in May last year. Both before and since that time, residents have repeatedly complained about the safety of the block, but were assured that there was no problem.

Councillor Judith Blakeman said questions would now be asked in the wake of those assurances.

“If the cladding was partly responsible for the fire we need to know what the specification for the cladding was and why it suddenly just went up (in flames) in about five minutes, because it should have been fire resistant, surely,” she said.

Ms Blakeman lives across the road and said she heard about the fire at 5am on the radio.

“I just rushed outside,” she said. “Neighbours had been watching it all night, they said the cladding went up like a nightdress by a fire – it just went whoosh.

“This is obviously part of the big refurbishment that finished about a year ago.”

Grenfell Tower fire: What we know so far

The tower was built in 1974. But the refurbishment work brought a number of changes – new areas were added to the building, as well as the cladding.

Experts have repeatedly warned that the addition of cladding, which is regularly used to refresh old or unsightly buildings, can help spread fire. It can work like a chimney, they have warned, bringing up air that allows it to spread across a building quickly.

Chartered surveyor and fire expert Arnold Tarling, from Hindwoods, said the process can create a 25-30mm cavity between the cladding and the insulation.

“It produces a wind tunnel and also traps any burning material between the rain cladding and the building," he said.

“So had it been insulated per se, the insulation could fall off and fall away from the building, but this is all contained inside.”

He said not all insulation used in the process is the more expensive non-flammable type.

“So basically you have got a cavity with a fire spreading behind it," he added.

Angus Law, of the BRE Centre for Fire Safety Engineering at the University of Edinburgh, said: “Early media reports suggest that this event has similarities with other fires that have occurred recently around the world.”

He added: “The UK’s regulatory framework for tall residential buildings is intended to prevent the spread of fire between floors and between apartments.

“If spread of fire does occur, as has happened at Grenfell Tower, the consequences are often catastrophic.”