What R-Value Insulation Do I Need for My Perth Home?

If you're building, renovating, or upgrading insulation, you've likely seen R-values like R2.0, R2.5, R4.0, R5.0 and beyond. But what do they really mean — and which one is right for your home?

This blog breaks down exactly what R-value insulation you need for Perth’s unique climate, based on local building codes, performance goals, and product availability.

What Does an R-Value Measure?

The R-value (or resistance value) tells you how well a material resists heat flow. Higher R-values mean better thermal performance — especially important for maintaining indoor comfort and reducing energy bills.

Perth sits in Climate Zone 5 under the National Construction Code (NCC), which recommends minimum R-values for each part of a home:

• Ceiling insulation: R5.0 to R7.0
• Wall insulation: R2.5 to R2.7
• Underfloor insulation: R2.0 to R2.5 (for suspended floors)

View the NCC insulation guidelines →

Best Ceiling Insulation for Perth Homes

In hot WA summers and chilly winters, your roof is where most heat gain and loss happens. That’s why ceiling insulation is essential.

• Earthwool R4.0 – Entry-level performance, ideal for budget-conscious retrofits
• Earthwool R5.0 – NCC-compliant and cost-effective
• Earthwool R7.0 – Top-tier energy efficiency for new builds

What About Walls?

Insulated walls help control temperature and reduce noise transfer between rooms and from outside. In Perth homes, we recommend:

• R2.0 Batts – Suitable for internal wall insulation
• R2.5 HD – Great for external walls
• R2.7 HD – Best for maximum acoustic and thermal benefit

Do I Need Underfloor Insulation?

If your home has timber floors, suspended floors, or open airflow beneath, underfloor insulation helps reduce heat loss and cold drafts.

• R2.5 Floorshield – Combines thermal and acoustic performance

Do Higher R-Values Always Mean Better?

Not necessarily. While higher R-values offer better resistance to heat flow, they also cost more and may not be suitable for every cavity. You should balance budget, space, and performance goals.

Pro tip: Going from R5.0 to R6.0 offers noticeable gains for Perth roofs. From R6.0 to R7.0, gains are smaller — but worthwhile for long-term energy savings.

Where to Buy Insulation in Perth

If you’re looking for an insulation warehouse near you, look no further. Perth Insulation Centre offers:

• Same-day pick-up in Canning Vale and Osborne Park
• Huge range of Earthwool batts for walls, ceilings, and floors
• Expert advice on NCC compliance and product selection

Explore by R-value:

• R2.0 Insulation
• R2.5 Insulation
• R3.5 Insulation
• R4.0 Insulation
• R5.0 Insulation
• R6.0 Insulation
• R7.0 Insulation

Need Help Choosing?

Our team has helped thousands of WA homes and commercial projects get the right insulation — whether it’s for a ceiling, shed, underfloor space, or full build.

Contact us today on 0417 910 326 or shop online now.