Wall warmth

New Zealand has more than it’s fair share of cold and draughty homes. The reason is a combination of underinvestment, poor design and poor maintenance. Home insulation only became mandatory in 1978, so if your home was constructed before then, it’s likely you are in need of insulation.
The monetary price we pay for un-insulated houses is in the form of wasted energy – from heating homes that are unable to retain heat. The damp and moisture are also a drawback, but more worrying still is the toll it can take on your family’s comfort and health.
Installing insulation in your walls will retain heat and contribute to a warm and healthy home. Insulation will stop the cold seeping in, prevent heat escaping and stop damp rising. Wall insulation can be made from polyester, wool, fibreglass and polystyrene.
R-values denote the type of fibreglass insulation perfect for your home:

• A minimum of R1.6 insulation in the North Island (excluding the Central Plateau)
• A minimum of R2.6 insulation in the South Island or Central Plateau.

Combine this with advice from trained professionals at Mitre 10 and online resources to make choosing your wall insulation a breeze.


Run through this checklist to assess your wall insulation status:

• Do you have wall insulation?
• Is your insulation gap free?
• Is your insulation dry?
• Does your insulation cover the whole area?

 
The easiest part is to get down to Mitre 10 to order enough for the job!
 
Installation
It's important to install your insulation correctly, as even a tiny gap can make it significantly less effective. Wall insulation can be easy to install depending on the state of your walls. If you are in the process of a new build then installing insulation in your walls, prior to attaching the linings, is relatively simple.
If on the other hand you need to remove your wall linings then this can create a larger project altogether. In the grand scheme of things, the cost benefit will outweigh the hassle.
Pulling your linings off the framing does NOT have to involve a sledgehammer!
It’s possible to pull out a few nails around the perimeter of the sheet and carry away the whole piece of Gib intact. This means you can use it again to save you money or stack easily for removal.
Fibreglass-based products are designed to friction fit between 600mm wall studs. Typically they measure 1140mm x 580mm, however if you find you have 400mm centered wall studs you will need a sharp Stanley knife to cut each piece to fit.
Reducing the gaps between your insulation and the wall studs is not enough – they must be eliminated entirely. Gaps around the edges will reduce the effective R-value of the insulation by approximately 3% for every 1mm gap.

Cut the R-value sticker off the bale and staple it to the framing for future reference.
 
When you are retro fitting insulation into externally facing walls, the backside will be exposed to the cladding. Condensation forms here so you will need to install underlay to protect your insulation from moisture. Use building paper such as Bitumac® 850 or Flamestop® 650 if the cladding is not-absorbent (steel or plastic), otherwise use a synthetic wrap and simply staple it to the internal perimeter of the stud cavities.
 
If you are using a polystyrene-based insulation, use a sharp utility knife to make your cuts accurate and straight – this will help you fit the insulation perfectly.
 
All the spaces within exterior walls need to be insulated between the top and bottom plates. Where there are split-level ceilings or floors, the area above and below the split needs to be well insulated. Using your off cuts to insulate around window and door frames will also help.
 
Timber should be completely dry before installing insulation.
 
With fibreglass products, simply friction fit it into place to ensure there is no movement over time. However, polystyrene is more rigid and any gaps need to be filled. Polystyrene insulation also needs a protective sheathing around wiring to prevent contact.
 
There are many great installers available if you’re unsure about your skill level for this project and the Mitre 10 team has a list to help you. One thing that’s for sure is once your insulation is installed, you and your family will notice the difference in terms of comfort, warmth and savings on your power bill.