How to top up your roof insulation

How to top up your roof insulation

James, Team member
View the video

How to top up your roof insulation

View the video
×

Project Overview

If your insulation is more than 15 years old, there is a good chance that gaps and drafts have developed. Topping up with new insulation will keep your home warmer in winter, cooler in summer and save you money on your heating and cooling costs.
Continue to step-by-step instructions

Step by Step Instructions

1 Be prepared
2 Measure your roof space
3 Tips for installing your insulation
4 Installing the insulation
5 Installing insulation in hard to reach places
6 Insulating around lights and electrical cables
7 Insulating the access hole

  • Step 1. Be prepared

    If you’re working up in the roof, the right preparation can save you from constantly climbing up and down the ladder. Start by turning off the power. You will also need a sharp knife for trimming the insulation, a tape measure, a non-conductive insulation stick, a kneeling board and a torch. Make sure you wear rubber soled shoes and suitable loose fitting clothes, including a long sleeved shirt, long pants, cap, gloves and dust mask. 

    Previous Step Next Step
    Choose the right insulation

  • Step 2. Measure your roof space

    Work out how much insulation you’ll need by calculating the square metres of your roof space. Measure the length and width of your roof space then multiply to two. The area each insulation roll covers is usually marked on its packaging. It can also be useful to draw a diagram of your roof space that includes lighting and electrical fittings.

    Previous Step Next Step
    old insulation roof space

  • Step 3. Tips for installing your insulation

    Lay the crawling board across three joists. This will give you a stable work platform and also somewhere to place your tools. Take the insulation bags up into the ceiling space before you cut them open. Insulation batts come in different sizes, so make sure you choose the one that fits snugly between your roof joists. And unless you have a very small access hole, make sure you measure first prior to cutting.

    Previous Step Next Step
    Earth wool insulation installation

  • Step 4. Installing the insulation

    Cut open a bag of insulation and let the batts expand to their original size. Cut the batts so they’re the right length and width. Start laying the insulation furthest away from the access hole then work your way back from the outside edges in. Install the insulation between the ceiling joists and butt pieces together at all joins. Save any off-cuts to fill in any remaining spaces.

    Previous Step Next Step
    installing roof insulation

  • Step 5. Installing insulation in hard to reach places

    The spaces around the edges and in the corners of your roof can be too low to safely install the insulation. When you find yourself in this situation, cut the insulation to size and use the non-conductive stick to put the batt into place and press it down.

    Previous Step Next Step
    Topping up insulation roof

  • Step 6. Insulating around lights and electrical cables

    Safety is paramount when you are installing insulation. Make sure you put all your weight on the joists as you work. If you need to install around downlights, cut a semi-circle out of two ends of the insulation and butt them together, leaving a 200mm gap either side of the light. Also make sure that any electrical cords and cables in the roof are sitting on top of the insulation and not under it.

    Previous Step Next Step
    Newly installed insulation

  • Step 7. Insulating the access hole

    To finish the job, insulate the top of your access panel by cutting a batt to size and stapling or gluing it into place. Now it’s time to reap the rewards of your D.I.Y. job, your home will stay warmer in winter and you’ll be saving money on your heating costs.
    Previous Step Next Step
    new insulation vs old roof

More D.I.Y. Advice

How to warm up your bathroom

Heating & Cooling How to warm up your bathroom The bathroom is where many people start and end their day. Keeping it dry and warm over the cooler months will make stepping out of the shower a little easier and your daily routine more enjoyable.

Use door snakes 02:59

Heating & Cooling How to winterproof your home You can save on your energy bills during winter with some simple D.I.Y. We've got some great ideas on how to winter proof your home to stop drafts and prevent heat loss.

Pet doors 02:54

Heating & Cooling How to create an airtight home To have an airtight home, you’ll need to prevent airflow leaving your home. We’ll show you some places which may leak air and what you’ll need to do to reduce it.

Woman filling small gaps with insulation 01:18

Heating & Cooling How to insulate walls Installing insulation in your walls is a great way to increase energy efficiency and reduce noise. Learn how easy it is to do yourself.

Material for insulating your ceiling 01:31

Heating & Cooling How to insulate a ceiling Keep your home warmer in winter and cooler in summer by insulating your ceilings. We’ll show you all you need to know about installing ceiling insulation.

Person holding an utility knife 03:24

Heating & Cooling How to insulate your home for extreme weather Find out how easy it is to keep your home warm in summer and cool in winter with insulation.

Use a safety screen 05:00

Heating & Cooling How to maintain wood heaters Wood fires are a cosy and economical way to heat your home, but they require regular maintenance. We’ll give you a few tips on what you need to do.

Moisture absorber 03:36

Heating & Cooling How to protect your home from dampness When you live in areas prone to high rainfall, such as the tropics, it’s important to protect your home from dampness and mould. We’ll show you how to do it in a few simple steps.

diy chalkboard cabinet hanging in the garage 01:27

Shelving & Storage D.I.Y. upcycled chalkboard cabinet We take an old cabinet and upcycle it into a handy chalkboard cabinet that will give you somewhere to store tools and a place to write lists or plans for your next project.

honeycomb wall shelves 02:23

Shelving & Storage How to make D.I.Y. honeycomb floating wall shelves These honeycomb floating wall shelves are a modern and stylish way to make a feature of any wall in your house. They’re easy to make and they’ll give a somewhere to show off your favourite things.

bathroom rejuvination 01:44

Ideas & Makeovers Learn how to give your bathroom a makeover on a budget Simple and affordable ways to give your tired bathroom a makeover.

roses in garden

Planting & Growing Winter garden ideas It may be cold outside in most parts of New Zealand but there are still a few things that need to be done in the garden at this time of the year. But if you can’t face going outside, you can always bring your garden inside suggests Bunnings horticul...

diy wood and concrete kitchen island 05:43

Outdoor Living D.I.Y. wood and concrete kitchen island You’d be surprised how easy it is to make this wooden and concrete kitchen island from just a few simple tools and materials.

Modern living room DIY makeover 01:29

Living Room How to give your living room a modern D.I.Y. makeover There are a few simple ways to freshen up a tired living room and make it a real feature in your home. You can create more space by knocking out a wall and updating the furnishings to fit. By adding floating cabinetry and open shelves, you’ll have m...

black diy wooden sofa arm table 02:49

Living Room D.I.Y. wooden sofa arm table A sofa arm table is a great addition if you’re short on space or don’t have a coffee table in your living area.

hampton kitchen

Ideas & Makeovers Hamptons sanctuary Bright, open and stylish are the hallmarks of the Hamptons Sanctuary. The island bench doubles as a workspace and breakfast bar, while the bamboo benchtops and window panel cupboards complete the look.

Top of the content