Ceiling and underfloor insulation is compulsory in all rental homes.

Where it is reasonably practicable, ceiling and underfloor insulation must be installed in rental homes since 1 July 2019. It must meet the standards set out in the regulations and be installed safely. Wall insulation is not compulsory.

The insulation regulations apply to any residential rental property covered by the Residential Tenancies Act, including houses rented by Housing New Zealand and registered Community Housing Providers.

Residential Tenancies (Smoke Alarms and Insulation) Regulations 2016 (external link)

The healthy homes standards include new requirements for insulation, which will take effect from 1 July 2021 onwards.

Landlords who installed new insulation since 2016 will likely meet the healthy homes insulation standard, provided the insulation remains in a reasonable condition. This is because the minimum R-values for new insulation have not changed under the healthy homes insulation standard.

However, landlords who didn’t previously need to improve their existing levels of insulation under the current requirements, may now need to do so under the healthy homes standards. Currently, if the property already has ceiling insulation which is at least 70mm thick and underfloor insulation, and both are in good condition, then landlords have not been required to take action.

Under the healthy homes standards, all rental properties will need to have insulation which meets minimum R-values. Existing ceiling insulation (that was installed before 1 July 2016) must have a minimum thickness of at least 120mm.

Ceiling insulation that is less than 120mm thick is acceptable if the landlord can prove the insulation’s R-value met the minimum R-values (2.9 or 3.3 depending on the climate zone) when it was installed and the insulation’s thickness has not degraded by more than 30% (compared to when it was installed).

More information about healthy homes standards

How to meet the current insulation regulations

Insulation is rated by how well it resists heat flow, measured by the R-value. The higher the R-value, the better the insulation.

If ceiling and underfloor insulation was installed in your rental property before July 2016

An upgrade may not be necessary at this time provided the insulation is in reasonable condition (e.g. no mould, dampness or gaps in the insulation), and achieved at least the minimum R-value when the insulation was installed.

Minimum R-values (only apply until the healthy homes standards compliance date for  insulation installed before 1 July 2016)

For timber-framed homes:

  • Ceiling R 1.9
  • Underfloor R 0.9

For masonry homes:

  • Ceiling R 1.5
  • Underfloor R 0.9

If any part of the existing insulation is not in reasonable condition, then the landlord must replace it with insulation that meets the new standard, as below. All insulation in rental homes must meet these minimum standards by the relevant healthy homes compliance date.

If there is no existing insulation or it was installed after 1 July 2016

Insulation in rentals needs to meet the minimum R-values listed below. The minimum R-value will depend on which part of the country the property is in. Please check your area using the below map:

Map of New Zealand climate zones

Minimum R-values for Zones 1 and 2:

  • Ceiling R 2.9
  • Underfloor R 1.3

Minimum R-values for Zone 3:

  • Ceiling R 3.3
  • Underfloor R 1.3

If a rental property is below these levels of insulation, it must be upgraded to meet the new standard.

Where there are multiple layers of insulation and all layers are in reasonable condition, then their product R-values may be combined.

A qualified professional insulation installer can advise you on the best way to meet the regulations.

Topping up existing insulation

Insulation that falls below the minimum requirements of the regulations will need to be topped up or replaced. Landlords should consider consulting a qualified professional insulation installer for the best way to meet the regulations.

EECA Energywise has advice on choosing an insulation installer (external link)

Meeting the New Zealand Standard

Whoever is installing the insulation must do it in accordance with New Zealand Standard NZS 4246:2016.

This gives guidance on the correct way to install insulation in an effective and safe way. It explains how anyone installing insulation should keep themselves safe and what safety clearances are required from downlights, chimney flues, roofing etc.

Download the New Zealand Standard NZS 4246:2016 Energy efficiency – Installing bulk thermal insulation in residential buildings [PDF, 6 MB]

Copyright in NZS 4246:2016 is held by the New Zealand Standards Executive. Standards New Zealand on behalf of the New Zealand Standards Executive has given permission to the Ministry of Business, Innovation and Employment (Tenancy Services) to provide access to the standard under copyright licence LN001211. The reader is permitted to view and print the 2016 edition of the standard free of charge (subject to printing costs) for your own use. You are not permitted to reproduce any part of it without prior written permission from Standards New Zealand unless your actions are covered by Part 3 of the Copyright Act 1994. (external link)

For queries about copyright please contact Standards New Zealand at copyright@standards.govt.nz.

Insulation costs

As a rough guide, the average cost of paying a professional installer to put in both ceiling and floor insulation is approximately $3,400 excluding GST for a 96m2 property.

Before choosing the product, check the cost per square metre of products with better performance – these have a higher thermal resistance or R-value. The prices of lower and higher-performing insulation products are often similar.

Landlords are responsible for the costs of insulating their rental homes. If a landlord increases the rent they must comply with the requirements in the Residential Tenancies Act.

Increasing rent has more on when and by how much landlords can increase rent.

Building design exceptions

Due to the design or construction constraints of some property types, it is sometimes either not physically possible to insulate or would require major renovations to do so.

Examples of types of properties that would meet exception criteria would be apartments where there is a habitable space above and below the apartment, houses constructed on concrete slabs where it is not feasible to install underfloor insulation, and homes with skillion roofs where there is no ceiling in place to install insulation above.

Access exceptions – what’s acceptable and what’s not

In many properties the most common way to access the ceiling space or underfloor to retrofit insulation would be through an existing trapdoor to the ceiling or an external door to crawl under the house.

Retrofitting insulation is not considered ‘reasonably practicable’ when an experienced professional insulation installer;

  • cannot access the location to install insulation without removing any cladding or lining, carrying out other substantial building work, or causing substantial damage to the property. 
  • cannot install insulation without creating health or safety risks to people, that are greater than the level of risk normally acceptable when insulation is being installed.

Where access to the ceiling or underfloor can be achieved by carrying out minor work (e.g.: temporarily removing base boards from the exterior of the property to access the underfloor), the landlord is expected to do so. The need for building work to be undertaken in order for insulation to be installed by an experienced professional does not satisfy criteria for an exception, unless substantial building work would be required, or substantial damage would be caused to the property. Any building work carried out must comply with the building code.

If the reason a property was excepted from complying with insulation requirements changes – for example a new roof is installed that allows room for insulation – then a landlord must ensure that insulation is installed as soon as is reasonably practicable.

If a landlord is in any doubt whether insulation can be installed in their rental property, they should consult an experienced professional insulation installer and, if needed, a builder. If the experienced professional says insulating some areas is not reasonably practicable or not possible, the landlord should ask for written confirmation of the reasons to include in tenancy agreements.

It is not adequate for a landlord to simply claim that ‘insulation is not reasonably practicable’. Failure to comply with insulation obligations under the new legislation could attract a penalty of $4000 for income-related rent landlords. For all other landlords this penalty applies from July 2019.

Other exceptions to insulation requirements

Other situations in which rental properties may be excepted from the insulation requirements are:

  • Where within 12 months of the start of a tenancy, the landlord intends to demolish or substantially rebuild all or part of the property. In this case the landlord must, if requested, provide evidence of having applied for the necessary resource consent and/or building consent for the redevelopment or building work.
  • Where a property is purchased from and immediately rented back to the former owner-occupier – in which case a 12 month exception will apply from the date of purchase.
  • If a property does not meet the new insulation requirements, but a landlord can provide evidence that when insulation was originally installed it did comply with particular insulation requirements (such as the specifications outlined in the building consent or an Acceptable Solution or Verification Method) the property is excluded from new requirements, provided the insulation is in reasonable condition.

What does installing insulation cost?

The cost of installing insulation depends on the size, shape and location of the building being insulated. As a rough guide, however, EECA advises that the average cost of paying a professional installer to put in both ceiling and floor insulation is approximately $3,400 excluding GST for a 96m2 property. You should generally expect to pay more than that for a larger home.

Before choosing the product, check the cost per square metre of products with better performance – these have a higher thermal resistance or R-value. The prices of lower and higher-performing insulation products are often similar.

Online tool
Do you need to take any action to comply with the insulation requirements under the healthy homes standards?

Use this tool to find out whether you need to upgrade the insulation in your rental property. This tool is not applicable for boarding houses.

Please note that the insulation standard doesn’t apply in some situations. These are:

  • if it is not practical for a professional installer to install insulation, such as if there is insufficient space to install insulation in the roof cavity or subfloor.
  • if you intend to demolish or substantially rebuild the home within 12 months
  • if the tenant was the previous owner of the property. In this situation, compliance with the insulation standard can be extended for 12 months from the date that tenancy commenced.
  • Exceptions to insulation requirements.

1. Have you installed all new insulation in the underfloor and ceiling that meets the current insulation standards under the Residential Tenancies Act?
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