As the company's owner and managing director, he said the idea of modifying containers has been active in the United States and Europe for the past two or three decades.
"We've always been trying to modify and market containers but the public awareness accelerated after the Christchurch earthquakes, when containers were converted into retail stores as a result.
"It was seen as funky and cool and we saw a big influx of inquiries," he said.
Mr Ward said their application was virtually endless.
"We've built recycling centres for councils all over the country, baches for holiday makers, small post office box lobbies for NZ Post, which is refurbishing a lot of its buildings as well. And we get a lot of orders to convert containers into offices.
"Construction companies are turning to them as their site offices because they're easy to relocate and are structurally very strong," he said.
Mr Ward said a lot of the fit-outs are based on photos clients send him. Citi-Box send the client a floor plan of a container and asks them to draw out a detailed floorplan. Then it goes through local authorities with the necessary working drawings.
"We don't build containers that comply with every individual building codes because each centre has a different set of rules. We build what the customer wants and then the customer organises what's required in terms of local codes."
At this stage, most of their sales are in Auckland, Palmerston North, Wellington and the South Island.
Mr Ward brings in the containers either brand new or near new from China. If they have been used they are less than a year old.
The modifications carried out in Wanganui by his small team include cutting ends out for doorways or windows, installing the doors and windows and fully lining the cube.
Most of the components such as paneling and doors, aluminium coverings and skirting boards are custom-made in China.
"We bring in a container-load of flat-packed components. One container will hold enough to built 21 offices. We can build a container office in three days now where at the start it took us nine to 10 days," he said.
"We'll cut out the holes for windows and doors and use locally-sourced steel to frame them. The only other thing we get done locally is aluminium joinery from Nu-Look Wanganui Ltd because that's far better quality than we can get in Asia."
Mr Ward said the containers were all insulated but the key to modifying them was putting in windows to give light and air flow.
"Containers are becoming more popular because they're very durable and can be easily picked up and relocated."
His own container-based office in Taupo Quay is solar-powered and he hasn't had a power bill to pay since he moved into it two years ago. The solar panels runs everything in the office, including computer and data systems, lighting, flat screen TV, radio and heating. And he's about to install a US-built central heating system.
"Most of containers we fit out are offices, smoko rooms, and the like, But the room for growth is mind-blowing."
He said the main difference between Citi-Box and the two or three major competitors in the market is that the Wanganui company does those fit-outs.
Mr Ward said Citi-Box succeeded because of strong business relationships he has worked hard to foster in places like Auckland.
"We're contracted to a major NZ company to do a huge rollout of container buildings. We can't reveal who that is until later next month but it means the volume of containers we've put through our business means we're getting our own containers made in Shanghai," he said.
"We're rolling this out over the next 18 months but I can tell you we're talking about hundreds and hundreds of containers.
"The first of these has arrived in the country and [they] are being sent out to the 80 branches around the country for the company we have the contract with."
He has recently returned from the Shanghai factory, which has been producing 50 containers a day for Citi-Box. He books production then flies to China to quality control the production run.
He said it represented a "huge feather in the cap" for his business and he said it showed again that businesses can succeed from a regional centre, such as Wanganui.
"You've just got to look further afield and look at those big centres. Small, agile businesses can adapt and change and react far quicker than a huge conglomerate," Mr Ward said.
