Did you know around 1,000,000 New Zealand homes have little or no underfloor insulation? And if you have ill-fitted tongue and groove planking, you’re probably shivering with particularly high heat loss. That’s why underfloor insulation should be installed at the same time as ceiling insulation.
Choosing insulation material
Underfloor insulation can be made from polyester, wool, fibreglass and a range of other materials. If you are comparing different types of insulation, remember to check the following:
- The insulation product should have been tested to the AS/NZS 4859.1 Standard. Look for a AS/NZS 4859.1 compliance statement on the packaging.
- In addition, look for manufacturers’ performance guarantees offered on the products
In the past, the most common material used for underfloor insulation was reflective foil, stapled along the floor joists. Reflective foils do not have an R-value by themselves, but work by trapping air between the floor and the foil, which serves as insulation. In addition, escaping heat is partially reflected back into the house.
The performance of underfloor foil depends on how well it is installed. Incorrect installation will significantly reduce effectiveness – which can be an expensive way to end up with floors that aren’t much warmer than before.
On top of that, installers face a serious risk of electrocution if the foil or staples used to fix it come into contact with live electric wires under the house. As foil is metal-based, it conducts electricity. Messy electric wiring is very common under New Zealand houses, and it can be hard to see during installation.
For these reasons, underfloor foil is not used in the Warm Up New Zealand: Heat Smart insulation retrofit programmes.
Bulk underfloor insulation includes polystyrene, wool, polyester or fibreglass. These products have an R value, and are easier to install correctly than foil products. In most cases, bulk underfloor insulation products are friction-fitted between the floor joists, i.e. they are held in place with one edge folded down to spring against the joist. Alternatively clips, staples or strapping, are used.
Products used in our insulation programme can not have air gaps as these may reduce the performance of the insulation.
Any moisture in the area underneath or around the edge of your floor can make your house damp and musty, and also reduce the effectiveness of your underfloor insulation.
Although dehumidifiers help fix the symptoms of damp problems, better drainage and/or an on-ground vapour barrier will fix the cause of the problem in many cases.
If the space beneath your house is damp, you will need to get any drainage issues checked by a professional such as a plumber. You can also consider installing an on-ground vapour barrier in enclosed underfloor spaces.
We’ll give you smart advice
Our experienced team can explain the pros and cons of various products and answer any questions you may have.
NOVAfloor Underfloor Insulation Click here to download information document