The first cafe in Canberra to introduce outdoor dining in the 1960s, Gus' Cafe in Garema Place, has been closed for three weeks.

Owner Janice Glenn says negotiations with new owners are continuing. "They want to refurbish it before it re-opens," Ms Glenn said. Property manager Savills has covered the cafe in "watch this space" signs.

The owner's lobbying in 2011 led to Gus' Cafe being heritage listed. There are two leases, the cafe building and the outdoor area, which was enclosed with timber-sash windows in 2014.

Then general manager Jamie Morris said the cafe's upgrade was unlike anything else in Canberra and took a year to get through the planning process. "The weather is so unpredictable, we needed to adapt to create an outdoor space for all kinds of weather. Some people like a window. Some like to open it, others like to leave it shut."

Mr Morris said said it was essential cafes work together. "Everyone is fighting for the takeaway trade, everyone has their regulars. I don't like that word competition, everyone has to want to work together."

The ACT Heritage Council says Gus' Cafe is an example of one of Canberra's cultural heritage places, illustrating intangible heritage values. It is not the physical fabric of the building that represents its heritage value. It is the history of the place and the activity conducted there over many years that gives the Gus' Cafe site its strong historic cultural and social heritage significance for the local community.

From 1960 a cafe has operated on the site and since 1970 it has included outside dining, pioneered by original owner Gus Petersilka. Subsequent owners retained the name.

"The name Gus' has become synonymous to the period of social and cultural development of Canberra in the 1970s, which saw the city centre acquire visible social vibrancy with the development of a cafe society," the heritage register says.

Gus Petersilka died in 1994. He was named "Canberran of the Year" in 1978; the Canberra Recognition Committee had a memorial plaque placed in the pavement outside the cafe in 1998; and a street in Gungahlin, Petersilka Street, was named in his honour in 2002.