Residents who were evacuated from an ageing Bristol tower block amid chaotic scenes may not be able to return for weeks after the city council confirmed that major flaws in its construction 65 years ago had left it at serious risk and said other blocks of the same vintage would now also be surveyed. About 400 people including an estimated 100 children have been told to leave Barton House, the oldest high-rise in the city council’s estate. Nine households refused to leave and 29 households could not be contacted, while the remainder stayed with friends and family or were put up in hotels and a rest centre at city hall. On Wednesday the Bristol mayor, Marvin Rees, said further surveys on the 15-storey block were needed before people could return. Asked if the building had been dangerous for 65 years, he said: “It wasn’t built in line with the design specifications so the answer by definition is yes.” Rees continued: “A survey of three out of 98 flats has indicated that the building may not have been built to the specification set out in its design. A number of issues have emerged that suggest the building’s construction is sufficiently different to its blueprints that there is a material risk to the structure of the block in the event of a fire, explosion or large impact. “This includes the apparent lack of structural ties between the floors and the load-bearing external walls. There is lower fire resistance of these structural elements and less concrete cover than set out in the original plans for the floors. Even if there was concrete cover as thick as set out in the original plans, this would still be less than would be used in a building built today.” Kye Dudd, the city council’s cabinet member for housing services, said that given there had been five recent fires in high-rise blocks, there was no choice but to evacuate. He said: “We’ve got no evidence that any other building has the same issue but we do regular surveys and given what’s happened we’re going to be extra vigilant, especially looking at our stock that is of similar vintage and design. “We’re not in a position to say how long the more extensive surveys [on Barton House] are going to take but I would say it’s days and weeks rather than anything longer.” There was anger and frustration over how the evacuation has been handled and growing concern that other blocks could also be at risk – a point that the city council has not answered despite repeated questions. Nuh Sharif, 42, a taxi driver, said he, his wife and two daughters had spent the night at a city centre hotel. “It was messy and the mattress was dirty,” he said. He returned to his flat on the sixth floor on Wednesday to pick up belongings including extra pillows and sheets. Sharif has lived at the flats since 2012 and said he would not feel safe there again. “Imagine if something happened – would the whole place fall down? I don’t know if they’ve learned the lessons from Grenfell,” he said. Shaban Ali, 36, was staying in his 11th-floor flat despite the call to evacuate. He said: “I had no alternative. I wasn’t offered anywhere else. They took my number and said they’d call but they didn’t.” Ali, who shares parental responsibility for his children, phoned their mother to ask her to look after them. “I’m frustrated and disappointed at the council’s response to this,” he said. “There’s a vacuum of leadership.” Ali criticised Rees, who is in Rwanda at a conference, for not speaking until 24 hours after the evacuation. “People are angry. I don’t think people will want to come back here now permanently and the fear is they’ll just dump us somewhere else.” He said some people were staying to look after pets, others because they feared their homes would be targeted. “People are so worried,” he said. Rayhan Ismail, who has two children aged six and three, said he and his family did not get to bed until midnight after the evacuation. “It was chaotic, really shocking,” he said. Khalid Abdi, a community worker, said people were panicking. “I saw residents collapsing to the floor, they were so shocked,” he said. Abdi said residents of other nearby blocks were concerned that they too could be affected. “The whole area is worried,” he said. Stuart Roberts, 44, who lives on the eighth floor of Barton House, said he was staying put. “I’m not going anywhere. They are wanting to put me in a bed and breakfast but I’m not moving. I can’t keep moving around. Families are being moved from pillar to post and it’s not right. This place isn’t going to fall down and I’m prepared to risk it.” Amid the gloom, there was some brightness. A local restaurant, Cafe Conscious, set itself up as a hub for residents and took in donated food, water, toiletries and nappies. “The community can be better at mobilising than the council,” said Rebecca Scott, a community leader.