How to Install Ceiling Insulation

Without ceiling insulation 30% of your home’s heat can be lost through your roof – especially in a lot of the older houses we have in New Zealand. Installing ceiling insulation will help keep your house warmer in winter, and cooler in summer. It can also help reduce your power bills. Follow this guide and you’ll see how to install ceiling insulation yourself, easy as.

Before you begin

• It’s a good idea to get an electrician to check the condition of your wiring – especially if you’ve got an older house. You’ll also want to check for any leaking pipes, and make sure you get any repairs done prior to starting.
   
• Familiarize yourself with “NZS4246 - Installing Insulation in Residential Buildings” – you can find this online.
   
• Because you are working close to wires, you’ll need to turn off the power. Take note of how long your fridge or freezer will be off.
   
• Check inside your pack for exact installation instructions, and to see what safety gear you’ll need to wear.
   
• Depending on what part of the country you live in will determine your insulation’s R Value. The R Value is simply a measure of the insulation’s effectiveness, and needs to be higher in the colder areas – your local store will stock the correct product for your area.

Measure up

• Work out the total area of your roof space in square meters.
   
• Check the pack for coverage information. This will help you determine how many packs you’ll need.
   
• Measure the distance between the joists in your roof. The product is available in different widths, so make sure you choose the right one. It will need to be at least 5-10mm wider than the space between your joists.

Installation

• Clear the roof of any old insulation.
• Clear the area of dust, cobwebs, or vermin.
• Turn the power off if working close to any wires.
• Load your bales of insulation into the roof.
• Start at the furthest corner from your manhole and work back towards it.
• Measure the distance between your joists.

• Use a utility knife on a hard surface to cut a section of insulation 5-10mm wider.
   
• Fit it in place so the section sits tightly between the joists. Make sure there are no creases, folds, or gaps. Do not compress it too tightly either.
   
• Use your insulation poker to push the insulation into any tight areas you can’t reach.
   
• If your roof has a low pitch, and space is very tight, you may need to cut a notch into the end of the insulation so it fits into the slope of the roof.
   
• When joining sections together simply butt them close together, ensuring there are no gaps, folds, or compressions.

Lighting, fans, etc

• You’ll need to cut a clear space around any lights or fans. This clear space will vary depending on what lighting or fan you have. Check “Section 4: Lighting” of “NZS4246 - Installing Insulation in Residential Buildings” to find out the correct clearance required for yours.
   
• Use two sections of insulation, each with a semi-circle at each end cut out around the light’s position. Simply butt the two sections together to form a circle around the light.
   
• If there is a transformer attached to the light, place it on top of the insulation.

Wiring

• Place the insulation under any wiring. If the wiring is attached to the joist, just butt it up so it fits tightly next to it.
   
• Glue a piece of insulation to the top of your manhole cover.
   
• Clear any tools or scraps out of your roof.