The building, located in Canberra Airport Group's Fairbairn Business Park, is expected to cost a total of $60 million and will house up to 730 employees across its 5200 square metres in a COVID safe way.

The majority of those employees will be from the Therapeutic Goods Administration (TGA) as well as other departmental staff.

The Department of Health's first assistant secretary Paul McCormack told the Public Works Committee the existing facility at Symonston was outdated and inflexible for the TGA's work.

"The existing facility at Symonston is no longer best supportive of the TGA in fulfilling this role," Mr McCormack said.

"It has served the Commonwealth very well, but it is almost 30 years old. It does not have the flexibility within its design to meet modern standards, testing or scientific methods or modern workforce amenity. It is expensive to run and the site itself provides very limited amenities for our staff."

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The department's assistant secretary Bernard Philbrick said the initial feedback over the move had been quite positive with most concerns raised over parking availability and public transport access.

"The majority of the feedback from [a staff] forum, which included anonymised questions, was quite positive," Mr Philbrick said.

"We note that there are 3000 car spots available nearby, which means more car spots are available than are available at the current Symonston site."

That figure was later downgraded to 2000, which is still considerably more than the existing facility's 371 spaces. The major difference was that they wouldn't be free, like those at Symonston were.

While Mr Philbrick initially said the annual cost of parking in one of those spaces would total $900 per annum, he said the weekly cost would be $42.50 or $8.50 a day.

Community and Public Sector Union deputy secretary Beth Vincent-Pietsch said while the building upgrade was welcomed, the major increase in parking costs for staff was of concern.

"Members see the upgrade of offices as necessary," Ms Vincent-Pietsch said.

"The union is concerned with the huge increase in parking price, and will be raising this with the department."

Staff would receive a discounted rate for the first year of the building's opening in mid-2022, Mr Philbrick said, but it was unclear if that arrangement would continue for the remaining 14 years of the department's initial lease there.

"Those rates are discounted for the first year, based on an offer from the Canberra Airport Group," Mr Philbrick said.

"Those rates vary, depending on the length of a parking pass that staff might purchase, but are competitive with rates around - and in fact are less than what staff would pay in the Woden area."

Canberra Airport Group and the ACT government were in "advanced negotiations" to instate a bus service between the airport and the building's site, according to Mr Cormack. Until then, the walk between the two sites is about a kilometre.

It's expected that will offer staff an alternative route for those without access to a vehicle.