Prisoners who share a cell when double-bunking is introduced at the Otago Corrections Facility (OCF) next year, will also have to share the shower and toilet.
An extra 150 beds will be available at the Milburn facility by February, as the Department of Corrections introduces double-bunking to help cope with rising prisoner numbers around the country.
Under the Official Information Act, the Otago Daily Times asked what work would be carried out at the 335-bed facility, how much it would cost and if the project could be completed within the next six months as planned.
While the department answered some questions, details about costs and other financial information were withheld.
OCF, which opened two years ago, was built with future capacity increases in mind.
The department said OCF - one of four prisons to have double-bunking introduced nationwide - was picked because it was among the safest and best equipped to handle the extra capacity.
It conducted an assessment of existing and future infrastructure needs, but believed the prison's existing infrastructure would cope with the extra demands.
The department confirmed no extra toilets or showers would be built into the cells used for double-bunking.
Extra car parking space would need to be built to cater for the extra visitors and staff.
It withheld details on the number of companies that registered interest in the double-bunking job.
"It is considered that releasing the information would be likely to unreasonably prejudice the commercial position of the department and withholding the information is necessary to enable the department to carry out commercial activities without prejudice or disadvantage."
"It said it was shortlisting companies and analysing their tenders.
"The successful applicant will be picked "in the coming weeks" and construction will start soon afterwards.
In response to questions about sourcing the estimated 70 extra staff needed when 150 more prisoners were housed at Milburn, it said the recruitment process had already started.
The extra staff would be a mixture of new, experienced and seconded staff from other specialised areas within the department.
