Landlords say the goals of the Healthy Homes Guarantee Bill have already been covered by changes in tenancy law and further regulations aren't necessary.

Their comments come after a New Zealand Union of Students Associations' submission on the bill detailed horror stories of mould, dampness and unfinished rooms, including the experience of a Palmerston North student's flat.

The bill calls for the Government to set minimum standards for heating and insulation for rental properties, a move labelled a rental "warrant of fitness" when the bill was in front of Parliament last year.

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Manawatu Property Investors' Association president Pauline Beissel​ said insulation requirements for rental properties were among changes made to the Residential Tenancies Act last year and issues around dampness and unfinished rooms were already covered by the act.

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Beissel said she was concerned a warrant of fitness would add unnecessary bureaucracy and expense, without adding anything to the planned changes.

The changes give landlords until 2019 to install ceiling and floor insulation where possible and from July 1, they have had to tell new tenants the level of insulation a property has.

Insulation would help with mould issues the students' association had cited, but it wouldn't solve the problem, Beissel said.

She said most mould problems were self-created, from things like drying clothes inside and using portable heaters.

Such practices put litres of water in the air, and without proper ventilation mould would grow.

Palmerston North landlord Shane Storey, who owns seven rental properties around the city, said he had a simple motto for running his properties: "warm, dry, clean and quiet".

He personally knew the health risks of landlords failing that obligation.

"I got bronchitis from rising damp in a flat when I was studying and I still suffer from that 30 years on."

All of his properties had full floor and ceiling insulation and were heated, and insulation was added to the walls as they needed work, Storey said.

But Storey didn't believe further Government intervention was needed to see an improvement in heating and insulation in rental properties.

"The market will sort itself out, I don't know if we need a law behind it to do it. These issues are the pressure points for a flat, particularly five- to seven-bedroom flats [like mine]. If you don't get on top of them, tenants move."

Landlord Paul O'Brien,​ on the other hand, thought a warrant of fitness for rental properties was a fair and sensible extension of current Government policy, and would reduce costs and strain on the health system.

"If it assists the health of tenants and [inspections] are a tax-deductible business expense, I fully support it."

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