The church, on Highcliff Rd, needed re-piling, as the old piles were in a pretty bad state, a Pukehiki Church trustee, Pat Robertson, said.
To give the trust a head start, the group of teenagers was hired to dig out under the church to make the old piles accessible for the contractors.
Between school, sport and part-time work commitments, the group of some five boys had spent about 70 hours digging earth from under the church, having devised a system entailing a sled and a trolley.
They had also dug a moat around the back of the church to help drain away rainwater.
Mrs Robertson said the boys were a great team and had made a magnificent job of getting the project started.
"The builders were amazed at how much they've done."
The trust was looking for funding to complete the work, she said.