What are the ground moisture barrier requirements ? If a rental property has an enclosed subfloor , a ground moisture barrier must be installed . This is generally a polythene sheet that can be bought from most building retailers and can be installed by a landlord or a building professional . Ground moisture barriers must either :
• Be a polythene sheet installed in accordance with section 8 of New Zealand Standard NZS 4246:20163 , or
• Have a vapour flow resistance of at least 50MNs / g and be installed by a professional installer .
What is classed as an enclosed subfloor space ? A subfloor space is enclosed if the airflow in and out of the subfloor space is obstructed along at least 50 % of the subfloor perimeter by :
• A masonry foundation wall
• Other claddings such as cement board or a solid timber skirt
• Attached structures , such as a garage or carport
• Earth or rock
• Any other solid obstruction to airflow .
The ground moisture barrier is required even if the property has subfloor vents .
What are the exemptions to the moisture and drainage standard ? There is one specific exemption to the moisture and drainage standard . This exemption covers properties where it is not reasonably practicable to install a ground moisture barrier . This would apply if a professional installer can ’ t access the area without :
• Carrying out substantial building work , or
• Causing substantial damage to the property , or
• Creating greater risks to a person ’ s health and safety than is normally acceptable , or
• It is otherwise not reasonably practicable for a professional installer to carry out the work .
Draught stopping
Any unreasonable gaps or holes in walls , windows , ceilings , floors and doors that cause noticeable draughts must be blocked . Landlords will have to block the fireplace or chimney of an open fireplace unless the tenant and landlord agree otherwise .
When is a gap or hole unreasonable ? To determine if a gap or hole is unreasonable and should be blocked , consider :
• The size and location of the gap or hole
• The extent of the draught that flows through the gap or hole
• If there is more than one gap or hole at the premises , and the extent of the total draught
• The impact of a draught on heat loss from the property .
Landlords can ’ t use the age and condition of the property as a reason not to stop gaps or holes . Gaps or holes greater than 3 mm in width that let air into or out of the home should be blocked . Generally , if a New Zealand $ 2 coin can fit in the gap and unreasonable draughts pass through this space , then the gap needs to be filled . ( Note : There are some situations where a gap may be smaller than 3mm yet still create an unreasonable draught and these situations should be assessed on a case by case basis ).
Examples of gaps or holes that should be blocked include :
• Poorly fitting windows or doors
• Large gaps between the bottom of the door and the floor
• Broken or loose hinges , catches or latches that prevent the door or window closing tightly
• Broken or poorly fitted pet doors
• Broken or cracked windows or doors .
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