Posted on 14 01 2021

What You Need to Know About the Healthy Homes Moisture Ingress and Drainage Standard

By now, the Healthy Homes Standards will be something you as a landlord are familiar with. Becoming law as of 1 July 2019, these standards include specific and minimum requirements that all rental properties must comply with. 

All private rental properties must comply with the five standards within 90 days of any new or renewed tenancy after 1 July 2021. As of 1 July 2024, all private rental properties must comply. 

Insulation, heating, ventilation, draught stopping, and moisture ingress and drainage standards aim to raise New Zealand’s housing standards and offer a better bill of health for New Zealanders.

Mould, dampness, and moisture are commonly inflicted upon many Kiwi homes, resulting in large bills and serious health problems. 

The moisture ingress and drainage standard will ensure your tenants’ health and the quality of the property. 

The Moisture Ingress and Drainage Standard

This standard states that rental properties must have efficient drainage to remove stormwater, surface water, and groundwater with an appropriate outfall. 

Rental properties must have a drainage system that includes:

  • • Gutters
  • • Downpipes
  • • Drains 

These will allow for appropriate removal of water from the roof and ensure that the rental home is not subject to periodic flooding during or after a normal amount of rain. 

If your property has an enclosed subfloor, there must be a ground moisture barrier installed (if reasonable to do so). 

What to Check For

There are some specific things you should check for when assessing your property to see if it complies:

  • • Ensure that it is safe for you to inspect the area and take any necessary safety precautions 
  • • Check to see if the underfloor insulation is in good condition 
  • • See if there are any appropriate drainage systems 
  • • Check that all gutters and downpipes are the right size and do not overflow during a normal rainfall 
  • • Check that all gutters have sufficient fall for water to flow (i.e., no stagnant water)
  • • Make sure that all gutters and downpipes are intact 
  • • Check there are no blockages or obstructions to any of the gutters or downpipes 
  • • Ensure that all downpipes are directing water to an appropriate outfall 

If you are unsure if your property’s current drainage systems comply with the Healthy Home Standard, GreenSide can provide you with an assessment to ensure that your property is appropriately following this and all other standards.

Ground Moisture Barriers 

Properties with a suspended floor (or subfloor) that is enclosed will now be required to have a ground moisture barrier installed. 

Generally, a ground moisture barrier is a polythene sheet that covers the subfloor and lowers moisture levels. 

Even if there is a vent built into the subfloor, it will still require a ground moisture barrier as the airflow is still significantly obstructed. 

If your property does have adequate ventilation but still experiences damp, a ground moisture barrier is recommended to reduce the moisture from entering. 

A ground moisture barrier installed before 1 July 2019 must be in good working condition. Otherwise, it will need to be replaced or fixed. 


However, there is an exemption to the moisture ingress and drainage standard. 

Ground moisture barriers do not have to be installed if it is considered not reasonably practical to do so. 

It is considered not reasonably practical if a professional installer can’t access the area without one of the following:

  • • Carrying out substantial building work
  • • Causing serious damage to the property
  • • Creating serious risk to a person’s health and safety
  • • Otherwise not reasonably practical to carry out the work

If you are unsure about whether or not your property is exempt, GreenSide will be able to assess whether or not it is practical and safe to install a ground moisture barrier. 

GreenSide Energy Solutions can help you choose the best options for installing a ground moisture barrier and assist you in making sure your property meets the Healthy Homes Standards. 

Our team of experienced and friendly assessors are ready to help you with the upcoming deadlines quickly and efficiently. 


As an Owner-Occupier You May Be Eligible for a Warmer Kiwi Homes Subsidy