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The Wisdom Of Throwing Money Down The Drain

In the final of a three-part series on Healthy Homes requirements we look at correct drainage and prevention of moisture ingress.

By: Joanna Mathers

2 July 2023

With climate change causing above-average rainfall around the country, the Healthy Homes provisions around drainage and moisture ingress are timely. All these standards need to be met by July 1, 2025 for all rentals: with any new or renewed tenancy requiring full adherence to the provisions immediately.

The correct drainage systems, and the prevention of moisture ingress, are imperative for keeping homes warm and dry.

The specifications for correct drainage are listed on the Tenancy Services website and the requirements are multifaceted. The following are needed for all rental homes: efficient, clean and working gutters that carry water away from all parts of the roof; gutters connected to downpipes; gutters installed sufficiently and maintained to eliminate water build-up or stagnant water.

Downpipes from guttering usually flow out to stormwater drains. But there may also be a properly working soakage system, natural watercourse, adequate water storage system or other constructed waterway, as stipulated by the Moisture Ingress and Drainage Guide available on the Tenancy Services website.

If you have a recent rental property you may have a report from a building surveyor, which will include the current state of the property’s drainage systems and guttering. In other cases the property’s drainage must be checked and up-to-date, depending on the type of tenancy.

Some of these checks may be done by a landlord or tenant, but if you don’t know where the drainage is, or if the guttering is not working efficiently, you may need to call in an expert.

Gutters must be efficient, clean and working and carry water away from the roof.


Moisture ingress is a phrase that refers to water penetration of the building from the outside. Water can penetrate through walls and floor, and if there is a lack of air flow, also within the foundation area or subfloor. This can be prevented by sufficient air flow, which keeps the subfloor dry enough to counteract moisture rising into the home’s flooring, and having a ground moisture barrier installed beneath the floor.

According to the Healthy Homes Act, rental properties with suspended floors, where the subfloor space is enclosed, must have a ground moisture barrier unless it is not reasonably practicable to install one.

Landlords need to ensure any existing moisture barrier (installed before July 1, 2019) is free from holes or tears which may allow moisture through. Existing ground moisture barriers need to be checked for signs of moisture on the surface. Moisture found in this inspection could be due to incorrect drainage, or leaking pipes, and would generally need to be dealt with by the correct professional.

Water can penetrate through walls and floor, and with a lack of air flow, within the foundation area or subfloor.
Existing ground moisture barriers need to be free from holes and tears.

Getting Help

Inspections for drainage and moisture ingress are best undertaken by professionals who specialise in Healthy Homes certification. There are many available online, but do your homework. The industry is still in its fledgling stage and there are some unscrupulous operators out there.

There are many companies offering full Healthy Homes assessments, starting from around $300. You will be looking at $1,000-$1,500 for a new installed ground moisture barrier; drainage solutions are likely to be upwards of $1,000.

Companies should provide certification and a detailed list of each area checked, alongside any issues. This certification needs to be held in case of Tenancy Tribunal claims – it is a checklist that can furnish any case with evidence if a tenant decides to make a claim against their landlord.


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