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How to insulate walls

Insulation batts neatly installed between the wooden cavity

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

1Measure and cut your insulation

To get started, you’ll need full access to the wall frame. This means removing any existing plasterboard or linings so you can clearly see the timber studs and noggins. Once the wall cavities are exposed, measure the gaps between the wall studs and between the noggins vertically. Most wall insulation batts come pre-cut to standard widths, but trimming them to fit each section neatly helps ensure there are no gaps or overlaps. Lay your insulation batt on a flat surface, then use a utility knife and straight edge to make clean cuts to size. The goal is a snug fit that sits firmly in the cavity without being squashed or stretched.
Measure the gaps between the wall cavity

2Choose the right type of insulation

Before installation, check that you’ve selected the right type of wall insulation for your needs. Thermal insulation is designed to help regulate indoor temperature, keeping things cooler in summer and warmer in winter. Acoustic insulation, on the other hand, is ideal for reducing sound transfer — especially handy in bedrooms, home offices or walls shared between living spaces. Some insulation batts offer a combination of both benefits. Always check the R-value on the packaging, which indicates how effective the wall insulation is. The higher values provide better thermal performance.
Choose the right type of wall insulation
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.