Does your home have any of these signs?
- Signs of excess moisture
- Musty smells in rooms that are closed for any period of time.
- Damp or mouldy clothes in wardrobes.
- Mould or mildew forming on ceilings and walls, as well as behind paintings, mirrors, etc.
- Stains or watermarks on ceilings or walls.
- Problems with areas of rotting wood in the structure of your house.
- Mould under your house.
There are several things you can to do to prevent prevent damp air from building up under the floor:
- Install underfloor insulation. The floor accounts for 10% of heat loss, so this will also reduce the amount of energy used in heating.
- Take a look under the house if you have a crawl space or basement, and if you’ve got loose dirt install a ground vapour barrier. This is a thick polythene sheeting installed on the ground under your house. It keeps moisture in the ground and stops air under the floor from getting damp. Read our FAQs below.
PROPERTY MANAGERS & LANDLORDS
If a rental property has a suspended floor and 50% or more of the sub-floor perimeter is obstructed, then a ground moisture barrier is required to meet the Healthy Homes Standards. If you know the rental already has a barrier installed, then it needs to be checked for any rips or tears as these allow moisture to flow and pool above the barrier and will need to be repaired or covered.
On average, 1.5 cups of water can evaporate from each 1m² of ground in 24 hours – that’s over 250 cups a day for a 150m² house! This moisture causes rot, mould, mildew, affecting health and causing expensive structural damage if not fixed.
So it’s important to reduce moisture levels by installing a ground moisture barrier so get in touch today and have a chat to our friendly team.
Common Questions Ground Moisture Barrier
WHAT IS A GROUND MOISTURE BARRIER?
A ground moisture barrier (also called on-ground vapour barrier) is a polythene groundsheet that is placed over the ground, under houses, to prevent rising dampness.
Ground moisture barriers installed after 1 July 2019 must either meet the specifications in NZS 4246:2016 or achieve a vapour flow resistance of at least 50 MNs/g and be installed by an appropriate professional installer.
Do I need a ground moisture barrier?
Many Kiwi homes suffer from damp and mould and subfloor moisture is potentially the largest source of moisture in the home depending on the occupants habits. BRANZ research shows us that this could be up to 40 litres each day under a 100 square metre house, even if the soil appears dry. If the subfloor ventilation is inadequate then much of this moisture will pass through the flooring and into the atmosphere inside the house. Often the subfloor ventilation will not be enough to fully get rid of this moisture.
Additionally, installing a ground moisture barrier for homes with an accessible sub-floor cavity is a requirement of the Moisture Ingress and Drainage Standard – Healthy Homes Standards 2019.
Do ground moisture barriers work?
Dollar for dollar, installing a ground moisture barrier is one of the best things you can do to improve the health and comfort of your home.
BRANZ research has found ground moisture barriers to be the most effective option at addressing subfloor moisture and more effective than subfloor vents.
CAN I INSTALL A GROUND MOISTURE BARRIER MYSELF?
Yes, it is possible to install a Ground Moisture Barrier yourself. However, it’s often not the nicest of jobs getting under the underfloor and crawling around in the dirt!
Our trained installers are experts and can install a Ground Moisture Barrier quickly and efficiently plus we guarantee our work for 5 years.
HOW MUCH DOES A MOISTURE BARRIER COST?
Installation of a 250mu Polythene Moisture Barriers that complies with new Healthy Home Standards, will cost $7.99 per m2
ARE THERE SUBSIDIES FOR GROUND MOISTURE BARRIERS?
Warmer Kiwi Homes grants are available to homeowners (not for rental properties) if you are also eligible for the insulation grant, so check the EECA website to see if you qualify.
IS A GROUND MOISTURE BARRIER REQUIRED FOR THE HEALTHY HOMES STANDARDS?
If your rental property has a suspended floor and 50% or more of the sub-floor perimeter is obstructed then a ground moisture barrier is required.
You can find more information on www.tenancy.govt.nz/healthy-homes/moisture-and-drainage-standard