Nearly three-quarters of start-ups are now based in co-working spaces, up from half a year ago, according to a major survey of founders, and the sites are running out of room.

The arrival of international co-working brands such as Rocketspace and WeWork have helped popularise the concept, according to Brad Delamare, general manager of Tank Stream Labs, which rents desks and hosts networking events for 90 companies across nearly 3000 square metres (sqm) on Bridge St in Sydney’s CBD.

“Co-working has become the natural option for start-ups before they’re big enough to rent their own offices. The contacts and growth you get out of it speak for themselves,” Mr Delamare said, pointing to professional services marketplace Expert360 as recent “graduate” from his space after growing too big for it.