In that time, the houses accommodated about 1000 men and women until they found their own home.
"We only take in released prisoners who have nowhere else to go when they come out," Dennis says.
"The owners understand what we are doing and support us - our only obligation is to pay the rent and keep the property tidy and clean.
"We are not judgmental. There are the basic rules - no smoking inside the house, no drugs and no alcohol - apart from that they are free to come and go, look for work and enjoy each others' company."
Dennis says without the house there is nowhere these people can go, except onto the street.
"No one wants to know them once they are released."
Rent and food is paid out of a WINZ benefit and the Steps to Freedom prison release programme.
Dennis works closely with WINZ and the Department of Corrections to help progress people through any bureaucratic paperwork as they apply for benefits and seek employment.
"Anybody we have had living here have mixed in well with others in the house.
"If there is a personality clash between the guys, we can address it at the first instance.
"Everyone helps each other out.
"They have their own space here - they treat it as their home."
A chance meeting with a house-owner four years ago gave Korowai House spokesman Pastor Manu Pohio, of the Faith Family Church, the motivation to set up a home environment for released prisoners.
"The owner was not using the house and was happy to have it tenanted, and give these people another chance," Manu says.
"It's like a home for these men - they cook and keep the place tidy - and it is proving far better than an institution for them to integrate back into society.
"The house is family-orientated with a strong spiritual component, which can help with the sudden life change these men are confronted with."
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John (not his real name) arrived at Korowai House three months ago after he was released early from his sentence at Waikeria Prison.
"I would have been living on the street if I had not known of this house to live in," he says.
"I'm not proud to say it but I had burned my bridges with my family and was not welcome to stay.
"The biggest advantage living here is that no one judges you, we all have similar backgrounds in that we have been in prison.
"We are all strangers at the beginning but it was important for me to come to live in the house because we all know each other's backgrounds."
John says the relaxed but organised living arrangement suited him until he was able to get a Housing New Zealand flat.
"It's like a family home, you can come and go but you have to do your share.
"At the same time there is always someone to talk to about anything on your mind."