Disclaimer:
This article provides general information about Healthy Homes moisture and drainage standards. Requirements may change, and specific situations may require professional assessment. Always verify current requirements with Tenancy Services or consult qualified professionals.
⚠️ Compliance Deadline Has Passed
As of 1 July 2025, ALL rental properties in New Zealand must comply with the Healthy Homes Standards, including the moisture ingress and drainage requirements. This applies to all private rentals, boarding houses, and Kāinga Ora properties. Non-compliance can result in penalties of up to $7,200 and tenants may be entitled to rent reductions.
Key Takeaways
- The 1 July 2025 deadline has passed — all rental properties must now comply with moisture and drainage standards.
- Landlords must identify and address any moisture risks that could reasonably be addressed.
- Efficient drainage must be provided for the removal of storm water, surface water, and ground water.
- Properties with enclosed subfloors must have a ground moisture barrier if moisture is entering from the ground.
- Gutters, downpipes, and drains must be maintained and functional.
- The standard focuses on moisture entering from outside the building, not moisture generated by tenants.
Excess moisture is one of the biggest threats to both property condition and tenant health. The Healthy Homes moisture ingress and drainage standard requires landlords to take reasonable steps to prevent water entering the home and ensure adequate drainage.
Unlike some Healthy Homes Standards that have specific measurements or thresholds, the moisture and drainage standard takes a more principles-based approach. It requires landlords to address moisture problems that can be reasonably identified and fixed, rather than meeting specific numerical targets.
Understanding the Standard
The moisture ingress and drainage standard has two main components: preventing moisture from entering the property, and ensuring adequate drainage to remove water from around the building. Both are essential for maintaining a dry, healthy home.
What Counts as Moisture Ingress?
Moisture ingress refers to water entering the building from outside. This includes water coming through the roof, walls, windows, foundations, or subfloor. It does not include moisture generated inside the home from cooking, showering, or drying clothes, though adequate ventilation helps manage internal moisture.
Common Sources of Moisture Ingress:
- Roof leaks: Damaged or ageing roofing materials, blocked gutters
- Wall penetration: Cracks, damaged cladding, poor flashings
- Window and door leaks: Failed seals, damaged frames
- Rising damp: Moisture coming up through concrete floors
- Subfloor moisture: Ground water entering under the house
Drainage Requirements
The property must have efficient drainage for storm water, surface water, and ground water. This means water should flow away from the building rather than pooling against foundations or entering under the house.
Gutters and Downpipes
Gutters must be clear of debris and in good condition to collect roof water effectively. Downpipes must be securely connected and direct water to appropriate drains or discharge points away from the building. Blocked or damaged gutters can cause water to overflow and damage walls or enter the subfloor area.
Surface Drainage
The ground around the building should slope away from foundations to prevent water pooling. Where natural drainage is inadequate, surface drains or channel drains may be needed to collect and redirect water.
Subfloor Drainage
For properties with crawl spaces or enclosed subfloors, adequate ventilation and drainage are essential. Subfloor vents should be clear and unobstructed. If water is entering the subfloor area, drainage solutions such as soak pits or subsoil drains may be required.
Ground Moisture Barriers
If your rental property has an enclosed subfloor and ground moisture is entering through the ground, you may need to install a ground moisture barrier. This is typically heavy-duty polythene sheeting laid over the ground to prevent moisture evaporating up into the subfloor space.
When a Ground Moisture Barrier is Required:
- The property has an enclosed subfloor (not concrete slab on ground)
- There is evidence of ground moisture entering the subfloor
- It is reasonably practicable to install a barrier
Signs of ground moisture include damp or musty smells, condensation under the floor, visible moisture on the ground in the subfloor area, or mould growth on floor joists and bearers.
Assessing Your Property
Landlords should conduct regular inspections to identify moisture issues. A systematic approach helps ensure nothing is missed.
Inspection Checklist
Walk around the exterior of the property looking for cracks in cladding, damaged or missing flashings, gaps around windows and doors, and signs of water staining. Check the roof for damaged or missing tiles, rust on metal roofing, and the condition of roof flashings and penetrations.
Inside, look for water stains on ceilings and walls, peeling paint or wallpaper, musty smells, and visible mould. In the subfloor area, check for standing water, damp soil, moisture on framing, and blocked vents.
Related: Property Inspections: Rights and Procedures
Addressing Moisture Problems
Once you identify moisture issues, you need to address them. The standard requires you to take reasonable steps, which means the cost and difficulty of fixing a problem should be weighed against the severity of the issue.
Quick Fixes
Some moisture problems have straightforward solutions: clearing gutters, replacing damaged downpipes, sealing gaps around windows, or clearing blocked drains. These should be addressed promptly as part of routine maintenance.
More Complex Issues
Significant moisture problems may require professional assessment and repair. Roof leaks might need a roofer, wall moisture issues could require a building surveyor, and complex drainage problems may need earthworks. While these can be costly, failing to address serious moisture issues can lead to major structural damage and health hazards.
Related: Ventilation Standards for Rental Properties
Documentation and Compliance
Keep records of your moisture and drainage assessments, any issues identified, and the work done to address them. This documentation demonstrates compliance and can be valuable if disputes arise.
Include a compliance statement in your tenancy agreement confirming the property meets the moisture and drainage standard. Update this statement when tenancies are renewed.
Related: Complete Guide to Healthy Homes Standards
Tenant Responsibilities
While landlords are responsible for the building's ability to resist moisture, tenants must use the property reasonably. This includes using ventilation when cooking and showering, reporting leaks or damage promptly, and not blocking subfloor vents or drains.
Educating tenants about moisture management helps protect both their health and your property. Consider providing guidance about ventilation use and what to report.
Frequently Asked Questions
Is mould in a rental property always the landlord's responsibility?
Not necessarily. If mould results from moisture ingress that the landlord should address, such as a leaking roof, it is the landlord's responsibility. However, if mould results from tenant behaviour, such as not using ventilation or drying clothes indoors without ventilation, it may be the tenant's responsibility. Often it is a combination of building issues and behaviour.
Do I need to install a ground moisture barrier in all properties?
No. Ground moisture barriers are only required where there is an enclosed subfloor and evidence that ground moisture is causing problems. Properties with concrete slab foundations do not require ground moisture barriers. If your subfloor is dry and well-ventilated, a barrier may not be necessary.
How often should I clean gutters to comply with the standard?
The standard does not specify a cleaning frequency. Gutters should be cleaned as often as necessary to keep them functional, which depends on factors like nearby trees. Most properties need gutter cleaning once or twice a year, but some may need more frequent attention.
What if fixing a moisture problem is very expensive?
The standard requires reasonable steps to be taken. For very expensive repairs, you should still address the issue, but the Tenancy Tribunal may consider cost when assessing compliance. Document the problem and your efforts to address it. Significant defects that cannot be reasonably fixed may affect whether the property should be rented.
Useful New Zealand property investor resources
Property investment rules change, especially around lending, tax, and tenancy obligations. Use these authoritative New Zealand sources to check current settings before making decisions.
Official and market sources
Related property ecosystem guides
- First Home Buyers Club
First-home buyer guides, calculators, and mortgage adviser support for New Zealand buyers.
- Homeowners Club
Refinancing, renovation, insurance, maintenance, and equity resources for NZ homeowners.
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