Families go through a rigorous interview process before being selected.
"We're looking for a family that's truly aspiring to own their own home and is ready to engage with us for up to 10 years," Mr LaPointe said.
Families helped by Habitat for Humanity did not earn enough or have sufficient savings, through no fault of their own, for a mortgage. Many struggled to pay rent or lived in overcrowded conditions. Two to three families to a house was not unusual.
If a family was found to be unsuitable, the most common reason was a high level of short-term debt. Families burdened with loans charging 25-30 per cent interest was an "insidious problem" all over the country, he said.
"We don't want to set them up to fail," he said.
Mr LaPointe said the organisation was expanding, thanks in part to a sizeable government grant. This year it was building three houses in Northland, next year it was planning five.
Ngawha prisoners' work on the current house was "absolutely first class".
Habitat for Humanity was hoping the prison could build two houses next year, which would stay in Kaikohe.
The organisation was looking into buying land and building four homes in the Mid North town.
Acting prison manager David Pattinson said the house was progressing well.
The first group of prisoners had built the framework, while the second group started training in the workshop this week.
"A NorthTec instructor is teaching this new group how to read and draw a house plan, as well as how to use equipment correctly."
Mr Pattinson said the project boosted prisoners' skills, giving them a better chance of finding work once they were released.