The state's peak strata body organisation has warned that apartment owners will foot the bill for building defects unless the NSW government spends hundreds of millions to fix the "systemic crisis".

Strata Community Association NSW president Chris Duggan urged the Berejiklian government to match Victoria's commitment, which would cover half the estimated $600 million cost of rectifying hundreds of high-risk buildings in that state and appeal for federal funding.

Sydney's city skyline. Credit:Peter Braig

But Mr Duggan estimated that $1 billion was "a more appropriate figure" to remedy the more than 600 buildings affected by combustible cladding.

"Enough is enough at this point in time. We've got a systemic crisis at the moment across NSW with defects, cladding and issues that are all stacked against consumers," Mr Duggan said.