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How to insulate walls

A person tucking an insulation batt behind a noggin on a stud a wall

Overview

Insulation in your walls reduces heating and cooling costs, and helps stop sound travelling between rooms. We'll teach you how to trim insulation batts to size and install them between the joists in your wall cavity.

Steps

1Install insulation batts in the wall cavity

Before you start, switch off the electricity and make sure all your electrical cables are safely out of the way. Then push the batts between the wall studs. Make sure you fill every gap in the cavity of your wall.
A person inserting an insulation batt between studs on a wall

2Trim the insulation to fill small gaps in the wall cavity

When you are insulating smaller spaces, measure the gap between the studs then trim your batt to size using a knife and a straight edge. Cut the batt slightly larger than the gap so it sits snugly in place. When the whole wall cavity is filled, you're ready to put your wall up.
A person tucking an insulation batt behind a noggin on a stud a wall
Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. 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 or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.