Types of Insulation

There’s a variety of insulation products to choose from and we have provided an overview below:



Glasswool is made using recycled glass bottles and is the most popular thermal insulation product in New Zealand and around the world. It provides both thermal and acoustic performance and can be used in a number of applications, including external walls, under floors, mid-floors, internal walls and ceilings. It can withstand temperatures up to 230°C. Glasswool can be compression packed, which means more area can be insulated per pack compared to other insulation products. It is the most cost-effective and sustainable insulation product available.

For more information on where glasswool insulation can be used when upgrading your home click here.

In New Zealand glasswool insulation is available in both segments and roll form for ease of installation. Blow-in glasswool insulation is also available to fill cavity walls and hard to reach areas. Approved installers will use a drilling pattern to create holes for blowing the insulation into existing wall cavities. Once the cavities are filled, the drill holes are repaired, ready for repainting. This eliminates the need to remove all architraves, scotias and plasterboard, and then re-line with new plasterboard. Blow-in glasswool insulation is ideal for the thermal upgrade of existing external walls and acoustic upgrade for internal walls, and provides minimal disruption for the occupier. Not all homes are suitable for blow-in insulation, and Council permits are currently required to insulate external walls.

NZ Collage

Rock mineral wool

Rock mineral wool is made mainly from volcanic rock, typically basalt and/or dolomite.  It is commonly used in high temperature and industrial applications as it can withstand temperatures up to 850°C.


Foam insulation such as XPS (Extruded Polystyrene) has high compressive strength and is water resistant. It is the ideal insulation for applications where there will be high weight load bearings such as green roofs and under concrete slabs. Foam insulation also provides high thermal performance and high impact resistance. For more information on foam insulation click here.

Sheep’s wool

Pure sheep’s wool insulation is not common. Most sheep’s wool insulation products contain a blend of polyester and old sheep’s wool from carpet and yarn suppliers. Sheep’s wool insulation products can be expensive due to high cost of production resulting from the low volumes produced. It is available as a loose fill or an insulation mat. Sheep’s wool products should state the percentage of actual sheep’s wool used in the product.


Polyester insulation is made from polyester fibres, which are melted and bonded together. Most polyester insulation products are manufactured using high percentages of raw (virgin) materials. These raw materials are petro-chemical based (plastics). This ensures that the product can recover to the thickness stated on the product packaging. As New Zealand does not have the facilities to recycle large volumes of plastic bottles, recycled content is primarily imported from Asia along with the virgin materials, before being combined locally. Polyester products have much lower levels of compression and recovery, which means less product per pack and higher transport costs compared to glasswool that has been compression packed. Polyester can be significantly more expensive than glasswool, and cannot achieve the same thermal (R) Values. For example,  polyester is only available up to R2.5 for standard 90mm walls, whereas glasswool is commonly available in R2.6 and R2.8 in the same thickness.