It is understood the build cost was about $10m.
Triple Star owner Pete Campbell says the project took 18 months with 12 to 15 builders in foreman Karl Poole's team.
Including subbies, there were sometimes up to 50 workers onsite.
Campbell praises his clients, an Aussie couple.
''They trusted us all the way along and made decisions where they needed to be made.''
Their son-in-law started doing a bit of work then stayed on when the borders shut, while his parents-in-law still haven't used it.
Campbell said challenges included a large excavation, tight timeframe, ''quite complicated services'' and working on five different buildings, albeit linked, rather than one.
He thinks the judges were impressed by the attention to detail and craftsmanship, and the interior design by Auckland's Trinity Interiors.
Meanwhile, Bennie Builders — which also won the 'renovation over $1m' category — was recognised for its work in completely transforming a tired 1975 Lockwood home into a contemporary-style retreat for Auckland clients.
''It's not a huge house but the job undertaking was massive,'' co-owner James Bennie said.
Including the landscaping, the build cost was close to $2m — the architects were Queenstown's Kerr Ritchie.
Bennie said up to eight crew were on the 10-month job.
The judges said: ''After stripping it back to its shell, the builder expertly fitted the exterior vertical dark-stained shiplap cedar, which was intricately detailed.''
Bennie said judges were impressed by ''the complexity of work carried out'', while he was delighted ''that all trades involved were very open-minded to see the transformation through''.
He notes ''the work we look for is something that's architecturally challenging''.
An example is the 'binocular house' on Queenstown's Hallenstein Street, which won the national 'multi-unit new home' category in 2017.
''We take on stuff that's pretty techy or got something about it only certain builders can take on.''
These two supreme award winners will be in the running for national awards announced this Friday.