New Zealand's biggest shopping mall is planning a major expansion, including multi-storey apartments and office blocks to create a "mini CBD".

House prices were stable in February, says the Real Estate Institute, while the number of properties sold recovered from a poor January.

The seasonally adjusted volume of residential building activity rose 7.4 per cent in the December quarter, while non-residential volume fell 6.1 per cent.

A primary school with a long-running problem of rotten timber and faulty cladding is to be almost completely demolished.