We only build about 20,000 houses nationally per year, and some of them are required for population growth. This means we will have our older buildings for a long time yet, so let’s fix them.
External insulation is not new; however, it has been poorly understood in NZ. We’ve made some buildings leak using materials that should not have been used. The method I used for the Parka Wrap research project was to overlay sensible materials on the existing wall. There’s a bunch of reasons for this. One of them is to avoid unnecessary waste, another is to avoid unnecessary disruption to the occupants, another is to use existing cladding as a substrate for new layers outside. The new layers are readily available in the market and can be seen in the photos here. They are the weathertight layer Solitex ADHERO, with a Rockwool outside that layer, then a batten to create a cavity with new cladding attached. The new uPVC windows from Starke are in the same position as normal, but now the insulation sits in-line so the thermal performance jumps radically.
These layers make up a robust weathertight assembly that not only prevents drafts through the walls but provides thermal improvement where insulation is now installed as a continuous blanket. I know it’s robust because I’ve tested it with water and ridiculous wind pressures in Shelby Wright Test Lab’s test booth, then racked the wall at high speed across 250mm of travel multiple times before testing again with more stormy weather.
It’s always down to the details, and the Parka Wrap Ltd team have developed three specific products to make it all the others stay together. In the photos you’ll see prototypes (now all in production and patents pending). They are, the depth-adjustable cavity closer at the base of the wall, the height-adjustable window support cam that allows us to place the window in the best spot in line with the insulation (‘Window Cam’), and a ‘Banana Bracket’ which copes with depth, angle and position variability across inconsistencies in an existing wall.
Make your walls do some work! Get in touch.