Installing Ceiling Insulation For The First Time? Read This First!

Tips for installing roof insulation

If you’re looking to improve the energy efficiency of your home, installing ceiling insulation is one of the best things you can do. Many people choose to install their insulation themselves while others decide to hire a professional. Either way, if it’s your first time installing ceiling insulation there are a few things you should know before you get started.

Here’s our guide on how to install ceiling insulation the right way.

Installing ceiling insulation in new homes

The best time to install ceiling insulation is during the construction or renovation phase when the ceiling cavity is exposed. Ceiling insulation can also be installed after the ceiling has been plastered although the process may be slightly trickier. 

If the ceiling cavity is exposed, insulation batts can be pushed between the ceiling joists from below with a long stick. It is important that you have the right sized batt so that it will fit snugly between the joists with no gaps. 

If installing the batts from underneath is not ideal, you can install insulation from within the roof cavity. It is a good idea to preload the ceiling with insulation before you start. Avoid installing during the hottest part of the day as the roof space can reach very high temperatures.

Video: How to Install Ceiling Insulation Before Plastering

Retrofitting ceiling insulation in existing homes

If you live in an older home or haven’t upgraded your insulation in a while, there’s good news. You can retrofit ceiling insulation batts in existing homes as long as there is safe access to the roof space. 

Did you know that insulating your roof can also help weatherproof your home and protect it from moisture issues? There are so many benefits to installing ceiling insulation in existing homes.

Video: How to Install Roof Insulation

Can you install new insulation over old insulation?

Your current ceiling insulation might not be doing the best job at keeping your home at a comfortable temperature, but that doesn’t necessarily mean you have to throw all of it out and start again. Old insulation may still have some insulating power which you can combine with your new insulation. The more the better! 

Before installing your new ceiling insulation on top of the old, you should carry out a thorough inspection. If the old insulation is damaged, mouldy or infested, it should be completely removed before the new insulation is installed.

Calculating the amount of insulation needed

It’s important to know how much insulation you need before you start the installation process. Not having enough insulation can slow down the process while getting too much insulation can be a costly mistake. 

The number of insulation bags required is easily calculated by dividing the number of square metres in the roof space by the number of square metres of insulation in the bags. We recommend deducting 10 percent off the total to allow for the timber framing itself. 

Video: What to Check Before Buying Roof Insulation

Can I DIY ceiling insulation?

Many people decide to install their insulation themselves. With the right equipment and safe access to your ceiling cavity, choosing to DIY can help you save on installation costs. 

However, it’s important to do your research beforehand to ensure a safe and effective installation. Poor installation – such as compressing or leaving gaps between batts – can significantly reduce the effectiveness of the insulation. 

How to install ceiling insulation

Step 1. Prepare

Make sure you have the correct type, size and amount of insulation product for your project. 

Step 2. Gather your tools

You will need a stanley knife, safety glasses, gloves and a long stick to help you get into hard to reach places. You might also want a wooden plank to kneel on – it’s more comfortable than kneeling on rafters.

Step 3. Install the batts

Start from the point furthest from the roof hatch and work your way backwards. Aim for a snug fit and an even height. You can trim the insulation to fit better and save the cut offs to fill in any gaps. 

Step 4. Leave clearances around downlights

Ensure you leave adequate space around ventilation, extractor fans, down lights and piping. You should put insulation under electrical cables where possible.

For more information about how to install ceiling insulation, visit our DIY insulation installation guide.

Safety tips for installing ceiling insulation

If you are planning to install your ceiling insulation yourself, make sure you take all the necessary safety precautions. These include: 

  • Safety glasses – the ceiling cavity can be a very dusty place, especially in older homes. Safety glasses keep your eyes protected from any dust, dirt and other particles you might come across.
  • Gloves – some insulation products can cause irritation to the skin so it’s best to wear gloves to protect your hands. Even if your insulation is itch-free (like polyester) gloves will help protect you from any dirt and rough surfaces in the roof cavity.
  • Long sleeves – long sleeve shirt and pants is highly recommended if you will be handling glasswool products. Glasswool contains minute fibres that can cause irritation to the skin.
  • Heat – if you will be installing insulation from the roof cavity, avoid doing so during hot weather as temperatures can soar inside the roof.
  • Ventilation – make sure there is adequate ventilation in the roof cavity. If the roof is tiled, you can remove some tiles to let in more air while you work.
  • Water – installing insulation can take a while. Ensure you have a bottle of water with you so you don’t have to go down to the house every time you need a drink.

What to Check Before Buying Roof Insulation

Best insulation for ceilings

Ceilings are the most important area of the home to insulate because that’s where the biggest heat loss and gain occurs. There are many ceiling insulation products on the market but the most important aspect to consider is the R-Value. 

A product with a higher R-Value is more effective at slowing down the transfer of heat. If you live in a warmer climate such as Perth, Brisbane or northern NSW, we recommend getting a minimum of R4.0 for your ceiling. For cooler climates like Melbourne, Sydney and Adelaide we recommend R5.0 or R6.0. Upgrading to a higher R-Value product can lead to greater energy savings. 

Insulation batts come pre cut to fit between the ceiling joists of most Australian homes. The standard sizes are 450mm and 600mm wide. Batts with a higher R-Value will be thicker than batts with a lower R-Value. 

Ceiling batts are most commonly made from glasswool or polyester. At Pricewise Insulation, we offer a wide range of high quality ceiling insulation batts from the most reputed brands such as Knauf, CSR Bradford, Fletcher and Autex. 

Browse our selection of ceiling insulation products or get in touch for more information. 

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7 thoughts on “Installing Ceiling Insulation For The First Time? Read This First!

  1. woody says:

    hi i am wanting to know if its worth putting scarfing along the rafters as well. inhale insulation bats. ultimately wanting to sheet up the roof space for storage and thought scarfing would be a good addition as its not too expensive.

  2. Jaco van Vuuren says:

    Hi, we have 200m2 ceiling for cleaning and installation. We have our batts ready to go. Can you quote on both please.

    • Pricewise Insulation says:

      Hi Jaco,

      If you live in Victoria then we recommend that you get in touch with EcoHome Insulation on 0433 678 728. They specialise in insulation removal and installing new batts in an existing home.


    • Pricewise Insulation says:

      Hi Sam,

      We recommend that you cut the insulation batts to fit between the timber joists. Glasswool insulation products such as Knauf Earthwool, Bradford Gold Batts and Fletcher Pink Batts are easy to cut with a retractable knife.

      The only time that insulation is laid across the ceiling joists is when there is already insulation (such as blow-in insulation) between the joists. In this situation, the batts are laid in the opposite direction to the timber joists. You can watch our video about this here: (skip to 1:30). Feel free to give our team a call on 1300 729 639 if you have any further questions.


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