"We've had all sorts of training drills and everybody did everything perfectly."
He was unaware of the cause of the fire, and said "it's still too early to tell what could have started it".
The blaze had destroyed the building, which was a 10m by 30m four-bay implement shed used as a workshop and storage area, Mr Napier said.
The razed building was not vital to production and its loss would not hamper routines at the farm.
"Fortunately, it's not going to affect production at all. It will be an inconvenience but we've got contingencies.
"Now we've just got to get stuck in to it and clean up."
Mr Napier said he had been initially alarmed at the risk the fire posed to workers, hens and other buildings at the site, but was "very relieved" the fire toll was not worse.
"I was certainly worried before the firefighters arrived. It seemed like an eternity from when you make the call to when they turn up, but it wasn't actually long at all," he said.
"The packaging inside the shed was the fuel for the fire and the black smoke and flame was the most frightening thing.
"But the fire brigade were really good, and the staff on site as well."
Wairarapa National Party candidate and businessman Alastair Scott is chairman of the board of Henergy Eggs, which has 80,000 hens living in barns.
Fire communications supervisor Murray Dunbar said firefighters isolated the blaze to the workshop and storage building and doused the fire from outside the structure while also preventing the flames from spreading to neighbouring buildings.
