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How to install ceiling insulation

A properly insulated ceiling

Overview

Did you know your ceiling is a significant contributor to your heating and cooling bills? You can lose up to 35 percent of your internal heat by having an uninsulated ceiling in winter. 

Making sure your ceiling is properly insulated will go a long way toward keeping your home warm in the winter months, while also helping it stay cool during the hot summer months. This could save you money on heating and cooling bills year-round.

If you want to install ceiling insulation in your home, check out our step-by-step guide.

Tip: Choose a cooler day to install your insulation – roofs are one of the hottest areas of your home in the summer. Remember to bring water with you and try to do the installation in the morning if summer installation can’t be avoided. 

Safety tip: Always wear the appropriate safety equipment (safety glasses, ear muffs, gloves and mask, for example) and always follow the instructions for the product or equipment.

Tools and materials

Tools

Materials

Steps

  1. 1

    Choose your 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. 

    Two packs of insulation batts of different types
  2. 2

    Prepare to install

    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.

    A Bunnings team member putting on protective gloves
  3. 3

    Measure the space

    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.)

    Space between two ceiling joists being measured with a tape measure
  4. 4

    Install the insulation

    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. 

    Insulation being laid down in the gaps in the ceiling
  5. 5

    Work around downlights

    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. 

    Space around a light fixture being kept clear of insulation
  6. 6

    Shop the range

    Check out our range of insulation at your local Bunnings store to get started on your own D.I.Y. home insulation.

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Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer.