Knauf-accredited cavity wall installer

Cavity Wall Insulation Perth

Insulation Extract installs cavity wall insulation in Perth double brick homes, injecting Knauf SUPAFIL® Carbon Plus glasswool into the empty gap between the brick skins. It lifts the thermal and acoustic performance of your walls without renovation, and we are the only Perth company certified and accredited to install it.

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Updated 18 October 2026

Double brick cavity wall insulation for Perth homes

Double brick is the signature of Perth housing. A large share of local homes have two skins of brick with an air gap between them, and in most existing homes that gap is empty. An empty cavity does very little to stop heat: the outer brick soaks up the afternoon sun, and in winter the inner wall stays cold long after the heater goes off.

Knauf SUPAFIL® Carbon Plus is designed for installation into existing and new cavity wall systems and significantly increases the thermal and acoustic performance of the wall. It is made from glasswool that is non-combustible to AS1530.1 and silicone treated for moisture and mould protection. It is injected into the cavities of masonry walls from inside or outside, including walls with a rendered outer skin.

Insulation hose injecting glasswool into an external brick wall

How cavity wall insulation cuts heat gain and heat loss

SUPAFIL® Carbon Plus creates an effective barrier inside the wall that significantly reduces heat transfer. In winter it helps keep warmth inside, and in summer it acts as a shield against external heat, reducing the need for air conditioning.

Approximately 35% of heat loss or gain in a home occurs through uninsulated cavity walls. This figure is based on indicative Housing Energy Rating Software (HERS) heating and cooling loads for homes in NatHERS Climate Zone 13, which covers Perth, using single-storey masonry cavity walls in various orientations with R2 and R4 ceiling insulation. The same modelling shows insulating the walls can lift a home's energy rating by up to 1.2 stars.

From R0.6 to R1.9 in a standard double brick wall

A double brick cavity without insulation typically has a thermal rating of about R0.6. Filling a standard 50mm cavity with SUPAFIL® Carbon Plus improves the wall system to R1.9, based on manufacturer testing. The improvement reduces power use, heating and cooling costs and the overall carbon footprint of an existing home.

Retains warmth in winter and blocks external heat in summer.
Uninsulated cavity walls account for approximately 35% of heat loss or gain.
Lifts a double brick cavity from R0.6 to R1.9.
Up to 1.2 stars improvement under NatHERS modelling.
Reduces energy loss through the walls by up to 65%.

Installer injecting cavity wall insulation through an internal plasterboard wall

Suitable for double brick, brick veneer and weatherboard cavities

SUPAFIL® Carbon Plus is engineered specifically for cavity walls, so it suits double brick, brick veneer and weatherboard construction where there is a cavity to fill. It is installed inside the wall, so the look of your home does not change.

Blown cavity wall insulation is a widely adopted method in the United Kingdom, used in more than five million homes to improve the thermal performance of existing housing, and it is equally suitable for Australian homes.

The material is silicone treated, which results in significantly less moisture in the cavity and reduces the build-up of mould over time. Cavity dampness can reduce the thermal performance of a building and create health concerns, so this matters in older homes.

Injection nozzle inserted into a mortar joint of a brick wall

Our cavity wall insulation installation process

Poorly installed or outdated insulation leads to energy losses, higher bills and discomfort. Cavity wall insulation fixes the walls of an existing home without major renovations or structural changes, saving time, energy and money and adding to the value of your property.

External cavity wall installation

Our installers drill small, neat 30mm holes in a zigzag pattern in the mortar joints of the double brick wall. The glasswool is pumped in at high density under pressure, filling every space in the cavity. The holes are then made good to match the existing mortar.

Internal cavity wall installation

Where external access is not practical, or for internal plasterboard walls, the insulation can be injected from inside the home through small holes that are patched afterwards.

Installers can complete up to 120m2 of wall a day, and no materials need to be stored on site. Because the cavity is filled completely, this method is considered the market-leading way to retrofit wall insulation.

Acoustic benefits of filled wall cavities

As well as its thermal properties, SUPAFIL® Carbon Plus offers excellent acoustic benefits once it fills the wall cavity. It reduces noise moving between rooms, such as footsteps and conversations, and helps block outside noise like traffic and neighbours.

As more Perth homes are built on smaller lots, owners often add a second storey to gain living space. Acoustic insulation in wall cavities is often overlooked in these projects because minimum standards for adjoining walls and floors are limited, and noise problems are only discovered after the build. Older homes face the same issues. Rather than costly post-build fixes, filling the cavity is a practical solution.

Cavity wall insulation performance table covering fire, vapour, microbial growth and combustibility

Durable, moisture resistant and vermin resistant

SUPAFIL® Carbon Plus is made from up to 80% recycled glass, so it has a low environmental impact, and unlike some traditional insulation it does not degrade over time. It keeps delivering energy savings without replacement or maintenance.

Because it fills the cavity completely, it leaves no space for vermin to nest and helps deter pests from moving through the walls. The glasswool has no termite attraction, does not create odours, and does not interfere with future electrical or gas work in the cavity.

Rat among electrical cables inside a house

Why choose Insulation Extract for cavity wall insulation in Perth

Getting the installation right is critical to the result. Insulation Extract is the lead accredited installer of Knauf cavity wall insulation in Perth, and our team is technically trained and certified by the manufacturer. We have seen what poorly installed insulation does to roofs, walls and floors, so we make sure every cavity is properly filled.

Compliant and certified
CodeMark certified and compliant with current Australian building standards.
Trusted manufacturer
produced by Knauf Insulation under ISO 9001 and ISO 14001 quality and environmental standards.
Experienced team
Insulation Extract has retrofitted more than 45,000 Australian homes since 2014.

Call (08) 9302 2699 to book a free cavity wall insulation assessment anywhere in the Perth metro area.

Specification table of insulation thickness, R-value and coverage

Thermal image showing heat escaping from the walls and windows of a house

Frequently Asked Questions

What is cavity wall insulation?

It is insulation injected into the gap between the two skins of a masonry wall. In Perth this is usually double brick. We use Knauf SUPAFIL® Carbon Plus glasswool, pumped in through small holes in the mortar joints.

How is SUPAFIL® Carbon Plus different from other wall insulation?

It is designed specifically for new and existing cavity walls. The glasswool is non-combustible to AS1530.1, silicone treated for moisture and mould protection, and made from up to 80% recycled glass.

How much difference does it make to a double brick wall?

A standard 50mm double brick cavity without insulation is about R0.6. Filled with SUPAFIL® Carbon Plus it rises to R1.9, based on manufacturer testing.

Is the installation invasive?

No. Installers drill small 30mm holes in a zigzag pattern in the mortar, pump the insulation in at high density and patch the holes. There is no demolition, and up to 120m2 of wall can be done in a day.

Does cavity wall insulation reduce noise?

Yes. Filling the cavity reduces noise moving between rooms and helps block outside noise such as traffic.

How long does cavity wall insulation last?

The glasswool does not break down over time, so it keeps working for the life of the wall without maintenance or replacement.