Mr Foster said the industry had lost workers to Christchurch and Auckland, and some firms could not find builders.
"That means they can't take on as much work."
The boom had seen the number of apprenticeships take a big lift after a long period when there was not enough work to justify taking on trainees.
Mr Foster said this was typical of the building industry.
"It is so up and down. It is flat out or dead quiet, there's no in between - it's so frustrating."
Western Bay Certified Builders president Mike Way said everyone in the industry was getting a lot busier.
"My phone is ringing a whole lot more."
He said he knew a painter who had, so far this year, quoted for jobs worth more than his total $300,000 turnover of 2013.
Mr Way also predicted customers would have to wait a bit longer to get their houses built because of the shortage of skilled tradespeople.
"It is starting to happen now. The reality is that some people will have to wait."
Signature Homes Western Bay branch owner Craig Williams said people were starting to poach builders but so far it was not a concern.
"We are looking at it all the time because if you don't plan for it, you will get into trouble ... at the moment it's fine."
He said his company's main waiting time was not caused by labour shortages but the length of time it took for the council to process consents.
It definitely took longer than the council's target of 20 working days, he said.
"Twenty working days is their dream."
Council consents issued last month worth $1 million or more were $3 million for stage one of the Brother electronics warehouse and head office at Tauriko, $1.4 million for a home at 43 Oceanview Rd and $1 million for a house at 307A Oceanbeach Rd.
Classic Builders Bay of Plenty sales manager Mark Hooper said more staff had been employed to cope with demand.
"It's a busy time to be in the building industry."
