Tenants are now looking beyond Stewart Dawson's, the traditional southern boundary of Wellington's office area.

Wellington's central business district is heading south if tenants are a gauge, according to a local real estate agency.

Steve Maitland, office leasing specialist with Colliers International, said the CBD had traditionally been bounded by The Terrace to Parliament and back along the waterfront to Stewart Dawson's, the corner of Willis St and Lambton Quay.

However, a flurry of recent office leasings have extended the CBD further south to Manners St, he said.

This was forcing a rethink of just where the "popular office zone" now lay.

"Refurbishment of Chews Lane, the consolidation of Spark into Willis St, recent leasings to Aurecon and Fairfax in the same building, and the seismic upgrade ... of The Majestic signal that this area of Wellington has been vastly improved and is gaining popularity with tenants," Maitland said.

"Tenants also find that rentals in this area are cheaper than comparable building rentals in Lambton Quay."

More than 700 staff will be added to the Manners St end of town when developer Maurice Clark finishes refurbishing the old Dominion Post building at 22 Boulcott Street for Transpower.

And an additional 3200 square metres of character office space will be available after Clark redevelops Community House at 84 Willis St, which will provide Transpower with Willis St access.

The upgrade would add some retail opportunities, said Maitland.

Other developments in the area include earthquake strengthening of TelTower in Willis St and other buildings, and an accommodation development underway next to St Mary of the Angels in Boulcott St.

There was also a proposal for a new retail and office development on the former Manners St Post Office site, owned by Cook Strait Properties.

"This activity will make this a vastly improved area of town and help provide a much needed shot in the arm for retailers trading in the area," Maitland said.

However, the newfound popularity of the Stewart Dawson's end of town had not yet translated into rent rises, Maitland said.

This was mostly because of a surplus of B-grade space in central Wellington, which could give prime locations a run for their money in some instances.

"There's still overall too much vacancy to justify the rent going up," he said.