How to install ceiling insulation

There are many different types of insulation available on the market, so do some research beforehand to ensure you’re choosing the best type for your home and budget. 

Some of the most common types of ceiling insulation include: 

Glass wool – Highly effective at blocking heat transfer and preventing condensation build-up in your roof space. It is also a very cost-effective option for insulating ceilings, as it can be bought cheaply in large rolls and installed easily with a staple gun. (This is what we used in our video.) 

Rockwool – Although it’s not as effective as glass wool when it comes to stopping heat transfer, it does have other benefits such as being less flammable than other types of insulation. This makes it popular for use in basements where there may be electrical equipment present. 

Polystyrene – Polystyrene foam boards are often used for insulating flat or sloping roofs where there are no obstructions such as rafters or joists. This type of board is relatively cheap to buy, it's easy to install and provides great insulation for relatively little thickness. 

Before you start, turn off power at the fuse box and make sure you have all of the proper proper safety equipment. You should wear gloves, safety glasses, ear muffs, a mask, a long-sleeved shirt, pants and protective shoes when working with insulation. This will help keep you safe from any potential hazards that could arise during the process.

Start by carefully removing any existing ceiling insulation and clearing the space of any dust, cobwebs or hidden pests. Once your area is clean, you’ll need to work out the total area of roof space in square metres using a tape measure.

Measure the length and width of your space and multiply them by each other to figure out your space in square metres (L x W = square metres). Double-check the packaging on your insulation to make sure you have enough to cover the surface area you’re working with.

Insulation comes in many different widths, so you need to make sure you choose the one that fits your space. To make sure the insulation fits snugly between the joists, look for something that is at least 5-10mm wider than the space between each joist. (Joists are the wooden beams that run across the space to provide structural integrity.)

Now you’re ready to install the insulation. Take your sealed insulation packs into the roof area and open them there, as they tend to expand once opened. 

Fill the space between each joist with your insulation, placing it snugly between each ceiling joist on top of the ceiling plaster. Carefully place the insulation pieces next to each other so that they are firm, flat and uniform in height. Fill in any gaps with off-cuts and trim the insulation where necessary. 

It’s important not to cover your downlights with insulation; the recommended gap around each downlight is 75mm. Where possible, place the insulation under any electrical cables and ductwork.