209-211 Maces Road, Bromley
Christchurch, New Zealand

Healthy Homes


(as it applies to Ground Moistures Barriers)

Healthy Homes standards came into effect and became law on the 1 July 2019 as it applies to Landlords, Property Managers, Councils, and Housing New Zealand. The new standards focus on five aspects of a property setting out minimum standards for heating, insulation, ventilation and moisture ingress as well as dealing with drainage issues and time frames, all designed to make New Zealand homes warmer and dryer.

Insulation standards have been common place for many years but up until now, very little importance has been given to controlling moisture from the ground – and yet this is arguably one of the most important areas to deal with first. The vast majority of homes built up until the 1970’s throughout New Zealand are of timber floor construction and while most will have a crawl space under the floor, many will not.

Since the introduction of the new legislation on 1 July 2019, properties with an enclosed sub floor space must also have a “Ground Moisture Barrier”. Independent tests have shown that up to 40 litres of moisture can rise off the ground every 24 hours. The moisture will often manifest in mould, mildew, musty smells, condensation and high RH values inside the house. This makes an effective ground moisture barrier, not only a common sense addition to the insulation armoury, but now since the introduction of the Healthy Homes Standards on 1 July 2019, a legislative requirement.


Extract from: Residential Tenancies (Healthy Homes Act 2019)

28     Suspended floors to have ground moisture barrier

    1. This regulation applies if –
      1. The tenancy building has a suspended floor; and
      2. The subfloor space is enclosed.
    2. The tenancy building’s subfloor space must –
      1. Have a ground moisture barrier that –
        1. is made of a material that meets the specification for an on ground vapour barrier set out in section 8 of NZS 4246:2016 and
        2. was installed in accordance with section 8 of NZS 4246:2016: OR
      2. have an alternative ground moisture barrier that –
        1. has a vapour flow resistance of at least 50 MN s/g: and
        2. was installed by an appropriate professional installer.

Thermofill Ground Moisture Barrier supplied and installed by Canterbury Foam Concrete complies with Residential Tenancies (Healthy Homes Standards) Regulations 2019 cl: 28, 2


In most cases Exemptions for a “Ground Moisture Barrier” won’t apply

    1. In the case where a home does not have sufficient space under the floor to install underfloor insulation, an exemption can be sought; however this does not nullify the requirement to install a “Ground Moisture Barrier”.
    2. The Healthy Homes Standards include the requirement that rental properties with an enclosed sub-floor space must have a ground moisture barrier, as part of the moisture ingress and drainage standard.
    3. If the rental property has an enclosed subfloor, a ground moisture barrier must be installed if it is reasonably practical to install one.

Canterbury Foam Concrete Ltd, as a professional installer is able, in most cases to install Thermofill Ground Moisture barrier, even when there is no crawl space;


Time Frames

As part of the healthy homes standards and in relation to time frames and compliance dates relating to ground moisture barriers:

    • Private rentals must comply within 90 days of any new or renewed tenancy after 1 July 2021;
    • Houses rented by Housing New Zealand and registered Community Housing providers must comply by 1 July 2023; and
    • All rental properties must comply by 1 July 2024.
    • Moisture ingress and drainage, landlords must provide a statement by 1 July 2020, stating that the rental property either;
    1. does not have any enclosed subfloor spaces or
    2. that each enclosed sub floor space has a ground moisture barrier (unless it is not reasonably practical to install one)


Moisture Ingress and Drainage

Rental properties must have efficient drainage for the removal of storm water, surface water and ground water. The drainage system includes gutters, down pipes and drains for the removal of water from the roof. Canterbury Foam Concrete recommends that ground surfaces should slope away from the foundation so that rain water doesn’t pond under the floor.