"Because of the economic downturn in the last few years the training of apprentices didn't happen as much and this is the backlash."
Mr Strong, who owns MPG Plumbing and Gas Services in Morrinsville, said people were primarily getting their heating sorted for winter, but there was also a rise in people wanting alterations and new appliances installed.
"Nationwide it's happening, but Auckland is struggling because of the building boom and Christchurch is starting to build up to Auckland levels because of the work being done down there."
Some people would have to wait up to a month if the work was not urgent, he said.
"If someone has no water or power, they are likely to be made a priority over a minor alteration so it pays to book your services well in advance."
Tony Mattson of Mattson Plumbers said demand always increased at this time of year, and his clients could expect delays of up to 10 days.
"The weather played a big part," he said. "There is a lot of heavy rain around this time of year and for my business that does a combination of gas fitting and heating, a lot of our resources are used for roof leaks and roof refits."
"We get a double hit half our guys are out running around fixing roof leaks and the other half are out fixing things like heating systems and furnaces."
5 ways to beat the winter rush
1 Book a service for your heating system in advance.
2 Clean your gutters and chimney.
3 Check your roof for leaks.
4 If you're buying a new heating system, choose a store that offers installation, it might help you skip the queue.
5 Phone around. If your regular tradie is booked out, try someone new.