R4.0 Insulation Thickness (Perth & WA): How Thick Is R4.0 Ceiling Insulation?
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If you're researching R4.0 insulation thickness, you're likely trying to confirm one key thing:
Will R4.0 insulation fit in my roof cavity?
This guide explains the standard thickness of R4.0 insulation, how it performs in Western Australia, and how to choose the correct batt size for your ceiling.
How Thick Is R4.0 Insulation?
For glasswool ceiling batts (including Earthwool), R4.0 insulation is typically around 195mm thick.
Thickness can vary slightly depending on manufacturer and product type, but in most WA residential ceiling applications:
- R4.0 glasswool batts ≈ 190–200mm thick
Example product: Earthwool R4.0 Ceiling Batts
For official performance details, see: R-Value Explained.
What Does R4.0 Mean?
R4.0 refers to the insulation’s thermal resistance value. The higher the R-value:
- The better the resistance to heat flow
- The greater the reduction in summer heat gain
- The better winter heat retention
In Perth and WA, R4.0 is considered a solid mid-level ceiling insulation option.
Is 195mm Thick Enough for WA Homes?
For many existing homes in Western Australia, R4.0 (≈195mm thick) is suitable when:
- Roof space depth is limited
- You are upgrading from older R2.0–R3.0 insulation
- You want a balance between performance and cost
However, many new builds now opt for higher R-values such as:
Will R4.0 Fit in My Roof?
Most WA homes with timber trusses have sufficient space for R4.0 batts.
Before purchasing, check:
- Roof cavity height
- Obstructions (ducting, downlights)
- Existing insulation thickness (if topping up)
You can use this guide: Insulation Size Guide.
R4.0 Insulation for Different Applications
Ceiling Insulation
≈195mm thick – most common use.
Wall Insulation
R4.0 is generally not used in standard 90mm wall cavities due to depth limitations. Wall batts are usually R2.0–R2.7.
Sheds & Workshops
R4.0 can be used in ceiling applications if adequate cavity depth exists.
Installation Considerations
To maintain full R-value performance:
- Do not compress batts
- Ensure full coverage without gaps
- Avoid blocking ventilation where required
See: Installation Information.
Where to Buy R4.0 Insulation in Perth & WA
Perth Insulation Centre supplies Earthwool R4.0 with delivery across Western Australia.
Browse the full range: Perth Insulation Centre
Summary: R4.0 Insulation Thickness
- Typical thickness: ≈195mm
- Suitable for many WA ceiling applications
- Solid mid-level thermal performance
- Good upgrade option from older insulation
If you're unsure whether R4.0 is the right thickness for your roof space, contact our team: