Quick guide to buying a healthy home

by Christian Hoerning

Homes look more appealing in warm sunshine but put some thought into how houses will perform in the cold depths of winter before you buy, as a house that is hard to heat can make you sick and miserable.

North facing

Ideally a house should be north facing to get winter sun. Rooms with unshaded windows on the north-facing side of the house get more heat and light from the sun, making them warmer and more pleasant to live in during the cooler months. Remember that the sun’s position is lower in winter, so objects cast longer shadows. Be aware that buildings or trees may block sun during the colder months.


The house will be very hard to heat if it doesn’t have adequate ceiling and underfloor insulation. If there’s an accessible roof and subfloor space it’s fairly straightforward to check if a home has adequate ceiling and underfloor insulation.

Pop your head through the hatch into your roof space — you will need to replace or top up the insulation if the insulation:

• is less than 12cm thick (ie should be thicker than the height of the ceiling joists)

• doesn’t cover the whole ceiling

• has gaps or places where it is squashed or tucked in

You need to remove the old insulation and start again if it is wet or damp in areas or has been damaged by rodents or birds.

Try to check under the house for underfloor insulation — it may need upgrading if it is loose, ripped or doesn’t extend under the whole floor.

If the house does not have insulation, budget about $4,000 to install insulation for a 100-square-metre house.

If the house does not have an accessible roof space, installing ceiling insulation will mean removing the roofing or ceiling lining which adds substantial costs. Similarly, if the house has a suspended floor that is too close to the ground to access, retrofitting underfloor insulation may not be possible.

If you are buying a property as an investment, tenants are more likely to stay long-term in homes that are warm, dry and easier to heat. Wall insulation and double glazing are a real bonus to look for. Wall insulation is common in houses built after 1978. In older houses retrofitting wall insulation usually requires removal of the wall linings or cladding. Get a registered building surveyor to check if the house has wall insulation as part of a prepurchase inspection.


Damp houses are unhealthy houses.

Musty smells, mould or water stains on walls, ceilings or under carpets and dampness under the house are all signs there may be a problem. Some of these issues may be easy to fix but before buying, it’s worth getting the house inspected by a registered building surveyor for hidden moisture content.

Look for extractor fans (externally vented) in kitchens and bathrooms, which are important for managing indoor moisture effectively. 


Energy efficient heating, sized properly for the area you are heating, is a real bonus.

Clean effective forms of heating include some heat pumps, modern wood or wood pellet burners and flued gas heaters.

If you want more details about what to look for when house buying, check out energywise.govt.nz/your-home/buyingand-renting.