Tech company Slack may be increasing its users at a healthy rate, but its plans to expand its Irish office have been held back by Dublin's lack of suitable space. Speaking at the Web Summit, founder Stewart Butterfield said the company was still planning to grow the office to more than 100 people as it announced when the office opened in May.

“There’s 25 people and we had hoped to grow it more quickly but we’ve been constrained by real estate,” he said. “We’d had two offers to lease that someone else ended up getting. We want to grow to a little over 100 people as quickly as we can. It’s really just a question of physical space. [Dublin] is quite competitive for commercial space.”

Software company Slack has its European headquarters in Dublin. The service offers a messaging platform for teams that brings communication from various channels into one place, creating a single archive that can be searched. It integrates with Twitter, Dropbox, Google Docs, Zendesk and Stripe, among others.

The company has its main offices in San Francisco, and also has a presence in Vancouver, meaning the Slack is well used to dealing with scarce and expensive office space.

“We’ll deal with it,” Mr Butterfield said. “Our other offices are in San Francisco and Vancouver, both of which are also extremely competitive and expensive and hard to find space.”

The ESRI warned in September that foreign companies investing in Ireland may find it difficult to get the space they needed to expand in the capital. The think tank had undertaken research with commercial agents Jones Lang LaSalle and found a lack of construction after the economic downturn could impact on investment by multinationals. It claimed a new employer of 500 people could face a wait of up to two years for suitable office space in Dublin.