UPSET: Rawhiti Marshall, left, brother Wiremu and mother Rebecca Clark say they are angry with Housing New Zealand plans to build another house on their back lawn.

Mother-of-four Rebecca Clark is fuming that Housing New Zealand plans to build another home in her back garden, leaving her no space for her family.

The single mum has rented the Papatoetoe state house for nearly 12 years and says she already struggles to accommodate her children in the three-bedroom home - her eldest son sleeps in the garage.

"My son is sleeping out there at the moment because his older sister has moved home. To make sure she has her space and a room he's jumped out into the garage so I can still have a room, otherwise I end up sleeping in the living room with no space for myself," she says.

But Housing NZ plans to remove the garage and build a two-bedroom home in the backyard.

Ms Clark says her family has been left with nowhere to go and "no answers" from Housing New Zealand.

Its regional manager Denise Fink says the property has been identified as part of the Right Size programme, which builds new, two-bedroom homes on the back of "larger, often under-utilised, sections".

The programme was launched last year and has already identified 85 sites for new two-bedroom homes in South Auckland.

"A number of properties across Auckland are part of this programme," Ms Fink says.

"There is currently a shortage of two-bedroom houses, particularly for single people with caregivers, couples and solo parents. We aim, through Right Size, to meet some of this demand to help people in need." Ms Fink says her staff will be working closely with the family to find them appropriate accommodation.

It is against tenancy agreements for anyone to be living in the garage, she says.

"We have been working with Ms Clark to help her understand the need and requirements of the Right Size project.

"We are also assessing her living situation and reviewing options for her future housing needs with her. This may include transferring her to another house should that better suit her current needs."

Ms Clark's younger son, 13-year-old Rawhiti Marshall, says he's disappointed with the corporation.

"I feel like they're stealing my home. We've lived here for 11 years . . . I know every single hiding spot, I know everywhere, now we just have to move."

The plans have caused a lot of stress for him and his family, he says.

"Today I had a free period and I was thinking to myself ‘where're we going to go, how're we going to get there?'

"I'm close to my school so I can walk but if we have to move I might have to catch a bus and that costs more money for my Mum and we don't have much money."

Ms Clark says she is tired of talking to "messengers" and is speaking out on the issue on behalf of others in her neighbourhood who are facing similar problems.

Meanwhile, Rawhiti says his ambitions have changed.

"One day I thought of buying this house when I was older. But now, since they're going to build a house at the back, I'd never buy it - too small."