Wall Insulation in Auckland is the second most important area you should look at, after your ceiling insulation but before your windows, particularly since an estimated 30-40% of the heat in your home is lost through the walls. Retro-fitted wall insulation is perhaps the least known and applies to most older properties. If your house was built before 1990, it probably has no wall insulation! Insultech Insulation uses a product called Cosy Wall Insulation to Retro-fitted wall insulation. Cosy Wall Insulation can only be installed by trained, licensed professionals and requires the certified CosyWall installer drilling small holes into your inner or outer walls and blowing in the insulation. Yes, and No. As long as you have a cavity or space that can fit insulation that is over 60mm deep then the type of wall does not matter. For unlined cavities (no gib) Insultech uses a traditional segment or biscuit type insulation. For Lined cavities Insultech uses a product called CosyWall insulation.