The jury at an inquest into the deaths of six people killed in a huge tower block fire said there had been "numerous opportunities" to carry out fire safety checks inside the building.
Dayana Francisquini, 26, and her children, six-year-old Thais, and Felipe, three, were among the victims of the fire at Lakanal House in Camberwell, south-east London, in July 2009. Helen Udoaka, 34, her three-week-old daughter Michelle and 31-year-old Catherine Hickman were also killed. They all lived on the 11th floor.
The jury returned a unanimous narrative verdict following an 11-week "super-inquest" into the deaths at Lambeth Town Hall.
Southwark Council was responsible for a "serious failure" over materials used in Ms Hickman's flat which were below the required standard for fire safety, the jury found. Their verdict stated: "The panels under the bedroom windows of flat 79 were not class 0, although they required to be. This was due to a serious failure on the part of SBDS (Southwark Building Design Service), its contractors and its subcontractors.
The jury went on to state that better fire proofing would have reduced the victims' exposure to smoke and "firefighters could have channelled resources more heavily towards search and rescue rather than active firefighting".
They added that a refurbishment in 2006/07 "provided numerous opportunities to consider whether the level of fire protection of the building was adequate".
The jurors decided that London Fire Brigade (LFB) personnel who took emergency calls from some of the victims failed to react to the situation when they told them to stay where they were. It would have been possible for them to escape without assistance, according to the jury.
Confusion over the layout of the flats meant those containing the victims were not reached in time to save their lives, the jury found.
Assistant Deputy Coroner Frances Kirkham told the inquest she would be sending recommendations to Southwark Council, LFB and Eric Pickles, the Secretary of State for Communities and Local Government. In her report to the council, she called for improvements to high-rise residential buildings.
A Department for Communities and Local Government spokesman said it would "carefully consider the recommendations" and "respond shortly".