A tradesman working at the University of Canterbury buys morning tea at the Hard Hat Cafe. Construction workers have been banned from other cafes on campus during term time.

Tradesmen working at University of Canterbury have been barred from campus cafes to stop "congestion" affecting students between lectures.

Cafe owners are not happy about the "heavy-handed" ban, saying they experienced no issues.

A university spokesman, Fletcher Construction and several cafes confirmed workers were told to stick to the Hard Hat Cafe, a container cafe set up specifically for them, or bring their own food.

DAVID WALKER/FAIRFAX NZ The Hard Hat Cafe was established for specifically for contractors, although students sometimes stop by for chips and gravy, staff said.

Security staff could enforce the ban, including moving tradies on if they were found in busy cafes during term time.

One cafe owner was "upset that our customers are being treated this way" after stand-offs with campus security and poor communication from university management.

"We have got racism and sexism – is this hi-vis-ism? It just doesn't make any sense," she said.

READ MORE:

* Ponsonby bar Longroom bans anyone under 22

* Canterbury hotel bans Lycra-clad cyclists

* Volstead bar does a U-turn on baby ban

* $1.1b for 10-year Canterbury Uni rebuild

The university spokesman said the ban, which was in the construction companies' contracts, was designed to ensure priority access for students, staff and visitors during the university's major rebuild and modernising project.

"At times we have had well over 1000 construction contractors on campus, and as many as 12 building sites," the spokesman said.

Management issued no directive about the ban, but it was possible cafe staff "may have otherwise become aware of [the university's] preference that contractors not be served", the spokesman said.

The 14 campus eateries are either privately owned or run by the University of Canterbury Students' Association (UCSA).

Cafe owners and managers feared risking their contracts if they were identified, but anonymously described their construction worker clientele as "like family" and dismissed the university's congestion concerns.

One said the tradies removed their work vests at the door and she continued serving them.

"They've been here for six years and they're lovely guys, no trouble. You do get to know them."

Another said campus security repeatedly warned her against serving contractors and removed them from her business. The university could not confirm the incidents but said they were "possible".

"We have struggled since 2011 with turnover and moving our premises from one place to the other and a lack of customers. The contractors over the years have really contributed positively to our business," the cafe manager said.

"We haven't been formally notified of anything. I have asked in writing, I have asked them [UC management] to explain but we haven't heard anything."

Staff at the Hard Hat Cafe said they would rather be the go-to for wage-earning tradesmen than struggling students.

Tradesmen seemed unfazed by the ban. Those approached said they were not aware of it and preferred the Hard Hat Cafe regardless.

A spokeswoman for Fletcher Construction, which is rebuilding the university's science block, said "our guys don't feel limited" by the ban.

UCSA president James Addington said while there may have been issues in the past, the association's cafes had not asked tradies to leave.