The number of people learning a trade is booming with Industry Training Federation (ITF) chief executive Josh Williams saying the number of apprentices had bounced back from a slump during the economic downturn, and some industries were near their capacity for new trainees.

Building and Construction Industry Training Organisation chief executive Ruma Karaitiana said apprentice numbers tended to fall when the economy was slow, and rise when it was strong.

This time, however, the recovery from the low point had been particularly quick, he said.

The increase had been driven by the improving economy, combined with the Christchurch rebuild and residential building in Auckland, Mr Karaitiana said.

He said there were a further 2000 building apprentices enrolled through polytechnics, for a total of 12,000, but more were needed.

The industry training organisations for building and construction, and its skills counterpart, said the average age of apprentices was between 24 and 26, but school leavers were an important source of trainees.

The ITF's Mr Williams said industry training organisations were now using their full allocation of $160 million a year in government funding, and expected they would need a further $20 million a year by 2018.

Source: RadioNZ