Most Kiwi homes are more like wooden tents than homes according to Bay of Plenty housing expert Nik Greggs.
They are damp, not properly insulated, poorly heated and need better ventilation, he says.
The Sustainability Options co-founder has been helping raise housing standards in the Rotorua free, for the past two years, but says "as a nation, we are living in wooden tents".
"We continue to build homes that are low standard compared to other Western nations."
His comments come a month before new housing laws kick in. Landlords face fines of up to $4000 if they don't have ceiling and underfloor insulation in their rental homes from July 1 onwards.
They follow a Rotorua Daily Post article about Rotorua Healthy Homes service's work to stop families developing life-threatening housing-related illnesses, such as rheumatic fever.
Gregg said many people lacked awareness and information about how to make their homes as warm, dry and cheap to run as possible.
Sustainability Options does not sell products, and tenants do not need their landlord's permission to have an assessment done.
Gregg said the team got a lot of requests for help from word of mouth and community presentations, but was keen and able to do more.
The not-for-profit business also helps businesses, community centres and schools. Its work covers everything from helping install insulation and double glazing to solar heating, rainwater harvesting, energy efficient lighting and appliances, waste minimisation, composting, worm farms and health audits.
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Team member Jo Wills emphasised in a presentation at the Rotorua Library on Thursday the importance of putting lids on pots on stoves, using an extractor fan or open window in bathrooms and kitchens, and closing doors in those rooms to stop moisture moving to other parts of the home.
"The dampest, mouldiest bedroom will often be the one right next to the bathroom."
Wills said drying one load of washing inside could create up to 5 litres of moisture, so it was best to put it outside.
"In New Zealand, we have to work extra hard to keep our homes warm, dry and healthy. We can't just let our homes do their own thing."
She said gas heaters without a flue created a litre of moisture every hour and emitted poisonous gases, so were best avoided.
Wills also reinforced the importance of lining curtains, even if windows were double glazed, and having a barrier on the ground under homes on piles, to stop moisture rising into the floor and rooms.
"This can be as simple as laying black polyethylene on top of the soil under your house."
Homeowner and pensioner, Geoff Miller, said the biggest problem for him was his power bill.
"The house constantly needs heating."
The 86-year-old planned to get a house assessment from Sustainability Options.
"I own my own house so why not look after my investment."
Rotorua mother Rowena Thompson said the trips about trapping heat with the likes of lined curtains were important for her.
"I am definitely going to get a free home assessment, just to make sure it's a healthy place for my baby, and to keep my power bills down. Last year the highest one I had was $450 so I have taken a lot of steps since then."
Sustainability Options visited Rotorua homeowner Ruth Thomas's property last December.
"I had already tried to put in ventilation, solar panels and insulation, but I wished I had done the assessment first, because the advice was so specific," Thomas told the Rotorua Daily Post yesterday.
She said some of the changes were really basic, such as lowering the average temperature of her hot water cylinder.
"A more major job was putting polyethylene on the ground below our underfloor insulation."
Sustainability Options has a contract with the Rotorua Lakes Council for up to $75,000 per year to June 2020.
In the year ending June 2018, 179 assessments were completed and 12 workshops held in the district.
The Bay of Plenty Regional Council also purchases assessments for homes under its air quality programme.
Insulation law deadline
Debbie Van Den Broek, the head of the Rotorua Property Investors Association, said it had not been hard for landlords to meet the new insulation standards coming in on July 1.
"Some people will always leave it to the last minute, but our members have done the work already."
She said most landlords wanted to provide a warm, insulated house, but installing insulation cost an average of $4000 for a medium-sized home, and was not tax deductible.
Van Den Broek said she had heard of some landlords who had chosen to sell their rental home, rather than meet the new insulation standards.
In her opinion, many of those properties were already in poor condition.
"It's probably good the tenants are getting out."
Rotorua Rentals director Pauline Evans said the new rules, announced in 2016, were a positive move.
Her team starting helping property owners respond two years ago.
"It has raised the standard of housing and made owners more aware of the condition of their properties."
She said property owners had faced challenges leading up to the July 1 deadline.
"[There were] delays from some insulation companies and lack of Government subsidies - removed in 2018 due to lack of funding. Some of our owners are tenants. Funding insulation upgrades has been a real challenge for them."
She said underfloor and ceiling insulation alone were not enough to keep a home warm, dry and healthy.
"Tenants have to take more responsibility for properly cleaning, ventilating and heating the property. We do not see any requirements or onus of responsibility on tenants."
Rotorua Harcourts director Erin Kingston also felt the new rules were a good move to improve the standard of living for tenants.
"We have focused on educating our landlords around this new legislation. The biggest challenge some landlords face with insulating their properties is around affordability.
"The Government gave a lot of grants to landlords for insulating rental properties in the early years but those landlords who didn't insulate quickly enough missed out on these. However, there are many options through banks and finance companies to aid with this."