Diversified company Hindmarsh says it has a variety of jobs and the scale to absorb the bumps ahead, while gathering momentum on a $35 million, nine-storey development near Woden Town Centre.

But Australian Institute of Architects ACT chapter president Tony Trobe said a forecast for the ACT construction sector delivered over breakfast last month was so gloomy, razor blades may as well have come with the orange juice.

Mr Trobe warned that architects were in for a sharp, bumpy ride as work dried up.

The forecast's presenter, Allen Consulting Group director Kerry Barwise, said the ACT's problem came from years of remarkable residential growth that could not be sustained.

''It was just so good, a lot of people would be bitter about that. I fear for industries built on that surge, it is not sustainable.''

But Mr Barwise said the ACT's strong ''background of activity'' in health, education, research and introduction of the national broadband network was enough without needing government intervention.

''If we stimulate, we might be building stuff we don't really want. Residential will soften, falling off a very high peak. If you stimulate, you could go away from those underlying fundamentals.''

While the news this week of Tralee being rezoned, opening the way for 2000 new homes south of Queanbeyan, has cheered the building industry, it could be one to two years before builders are on site.

ACT Master Builders Association spokesman Jerry Howard said the building workforce had shrunk from 15,000 to 12,000 workers.

''If you lost 3000 - even 300 people - in any other industry, there'd be a massive outcry.

''We desperately need a couple of large projects.

''A lot of people are moving on, and now that Sydney is starting to pick up, they're going back there.''

Mr Howard said Jamison Inn, a multi-storey redevelopment at Macquarie now in receivership, showed even a full construction pipeline was vulnerable to sluggish pre-sales in the units market.

''We must be getting to a point where we need to take a breather. We have gone from chronic under-supply to where we must be nearly at equilibrium.

''Still, people are saying if they can get land in the right location they will build to meet demand.''

Hindmarsh project manager Michael Gilmour said the workforce at Sorell's nine-storey development would swell to 200 at its peak when internal fit-outs began in a couple of months.

Hindmarsh development manager Brett Smith said the 18-storey Altitude at Belconnen, Woden Green - a joint-venture with the Land Development Agency, and four projects in Constitution Avenue, including redevelopment of the RSL national headquarters, would keep workers busy.