"We have just opened our 38th Mitre 10 Mega store in Auckland's new Westgate development and we have further openings planned for next year," Cowie said.
"We're continuing the refresh of our Mitre 10 stores, having completed 15 stores this past year, and are also investing strongly into programmes to help our customers build their DIY knowledge."
Three new Mitre 10 Megas, each worth about $20 million, would be built next year in Christchurch, Hamilton and Queenstown.
Chris Dibble, Colliers International's national research manager, said Mitre 10 was one of the country's fastest-growing businesses, spurred by the growing economy, rising retail sales, migration, Auckland's fast expansion and the Canterbury rebuild.
Dibble forecast further success.
"If it can keep up with the right strategy and plans, I think that's a good indication that it's another successful year ahead," he said.
"Retail sales growth has been predominantly in Auckland," he said, referring to the chain's expansion in the city.
Cowie said the chain's newest store was the 38th Mitre 10 Mega at Westgate on Auckland's northwestern fringes.
Dippie said the chain was also paying members more.
"Our distributions to members were also up 11.1 per cent on last year to $58 million, while share capital increased by 5.1 per cent to $46 million," he said. Last year, members were paid $52.3 million.
Cowie cited the Easy As campaign, which had helped push retail growth.
"We have seen close to 3.5 million views of our videos since the launch in April 2012, and we're also continuing to see growth in our trade business," he said.
"The 40-year mark is an exceptional milestone - it's been a fantastic journey of inter-generational growth.
"Our founding families of the business could never have envisaged that in 2014 we'd be celebrating 40 successful years as well as turning over $1 billion worth of business."
Statistics NZ data for the September 2014 quarter showed retail sales volumes up 1.5 per cent, 12 of 15 industries with higher sales volumes and supermarket and grocery stores recording the largest rise, up 1.9 per cent.
Hardware, building and garden supplies as well as furniture, floor coverings, houseware and textiles are growth areas, the data shows.
40 years of DIY
• Stores: 81, of which 38 are Mitre 10 mega stores.
• Staff: About 5,000
• Structure: Co-operative; NZ-owned
• Customers: 1.4 million a year
• Growth: Sales up 10.1%
• History: Started 1974
- Source: Mitre 10