The cost of fixing the unfolding national building crisis, including widespread residential apartment block defects and the use of dangerous combustible cladding, could soar past $6.2 billion, according to a new economic analysis. More than 3400 residential unit blocks across the country have potentially flammable exterior cladding, according to a report commissioned by the construction union. Those high-rise blocks take in about 170,000 apartments. In NSW, hundreds of buildings are potentially affected. Pressure is mounting on the Berejiklian government to provide more support and funding either to individual owners’ corporations, or to Sydney councils confronted with buildings that could need flammable cladding ripped off and replaced.