Understanding Roof Insulation for Metal Roofing
Installing roof insulation for metal roofing is one of the most effective ways to improve comfort and energy efficiency in your home, shed, or commercial building. A properly insulated metal roof helps reduce heat transfer, condensation, and noise, keeping indoor temperatures stable all year round. Whether you’re working with COLORBOND® or ZINCALUME® sheets, insulation is essential for performance and long-term durability.
At Metal Roofing Online, we supply foil and blanket insulation rolls designed to fit perfectly beneath metal roof sheets, providing both thermal and acoustic protection. All materials are manufactured to Australian standards and backed by reputable brands trusted by tradies nationwide.
Foil vs Blanket Insulation — Which is Best?
Choosing between foil insulation and insulation blankets depends on your climate and roofing needs. Here’s how to decide which option suits you best:
- Foil roof insulation — acts as a radiant barrier, reflecting up to 95% of heat. Ideal for sheds, garages, and hot climates where radiant heat is the main concern.
- Roof blanket insulation — thicker and denser, providing better sound absorption and thermal performance for homes and commercial roofs.
- Combination foil-backed blanket — the ultimate choice for superior comfort, condensation control, and energy savings in all Australian conditions.
Explore our full range: Roof Insulation Blanket (Foil-Faced) and Foil Roof Insulation (Under-Roof).
Roof Preparation & Flashings
Before installing any roof insulation or reflective foil, it’s essential to make sure that all flashing edges are sealed and secure to prevent condensation and water ingress. For a complete, watertight finish, explore our range of custom COLORBOND® roof flashings — available in ridge, barge, apron and valley profiles to suit every project.
Choosing the Right R-Value for Australian Roofs
The R-value of insulation measures how well it resists heat flow — the higher the R-value, the better the thermal performance. For Australian metal roofs:
- QLD & NT: R2.0 – R2.5 recommended for radiant heat control
- NSW & VIC: R2.5 – R3.0 ideal for balanced climates
- TAS: R3.0 – R3.5 for colder conditions
If you’re unsure which roof insulation rating suits your project, contact our team for expert advice — we’ll help match your insulation to your roofing profile and climate zone.
Preventing Condensation Under Metal Roofs
Condensation is one of the biggest issues in uninsulated metal roofing. When warm indoor air meets cold roof sheets, moisture forms — leading to corrosion, water staining, and mould. Installing foil insulation or a foil-backed blanket provides a vapour barrier that helps prevent condensation under COLORBOND® and ZINCALUME® roofs.
For added protection, pair your insulation with Sisalation® foil sarking or roofing fasteners designed for sealed installations. These products work together to improve roof lifespan and interior comfort.
Installation Tips & FAQs
Where does insulation go under a metal roof?
Insulation is installed directly under the roof sheets, usually between battens and purlins. Foil insulation faces downwards to reflect radiant heat, while the blanket provides acoustic and thermal mass.
Can I install roof insulation myself?
Yes. Our DIY insulation rolls are easy to cut and handle. Always wear gloves and ensure the foil side faces down to reflect heat. For larger builds, consider a qualified installer for optimal results.
Is roof insulation worth it for sheds and garages?
Absolutely. Even small structures benefit from insulation. Foil or combo insulation reduces radiant heat, minimises condensation, and helps protect tools, vehicles, and stored items from moisture.
What’s the difference between roof blanket and under-roof foil?
Foil insulation reflects radiant heat, while roof blankets absorb and slow heat transfer. For best results, combine both for comprehensive protection against heat, cold, and noise.
Why Buy Roof Insulation from Metal Roofing Online
- 100% Australian-owned and trusted by tradies since 2002
- Genuine BlueScope steel-compatible products for COLORBOND® and ZINCALUME® roofs
- Fast dispatch across VIC, NSW, QLD, TAS & ACT
- All prices include GST – no hidden fees
- Secure online checkout, ABN tax invoices, and delivery tracking
Upgrade your home’s energy efficiency and comfort today — order roof insulation online from Metal Roofing Online and enjoy trusted products backed by BlueScope performance warranties.
Last updated: October 2025
Foil vs Blanket Insulation — Quick Comparison
| Feature |
Foil Roof Insulation |
Roof Blanket Insulation |
Best Use Case |
| Primary Function |
Reflects radiant heat — keeps interiors cooler in summer |
Absorbs and slows conductive heat flow & reduces noise |
Warm or hot climates; sheds & garages | Residential homes & commercial builds |
| Material Type |
Foil-faced poly cell or air bubble membrane (barrier film) |
Fibreglass or polyester blanket with foil laminate |
Pair with sarking or roofing fasteners |
| Thermal Performance (R-Value) |
R 1.5 – R 2.0 typical (primarily radiant barrier) |
R 2.5 – R 3.5 depending on thickness and brand |
Combine foil + blanket for optimal R-value & energy savings |
| Condensation Control |
Acts as vapour barrier — reduces moisture under metal roof |
Retains some moisture; best used with foil facing down |
Metal roof projects in humid zones (QLD / NSW coastal) |
| Noise Reduction |
Moderate (when combined with ceiling batts) |
High — reduces rain & wind noise under metal roof |
Residential homes & workshops needing acoustic control |
| Ease of Installation |
Lightweight & DIY-friendly rolls |
Slightly heavier — best with two installers |
DIY projects vs trade installations for new builds |
| Typical Product Examples |
Foil Roof Insulation (Under-Roof) |
55 mm Roof Insulation Blanket (Foil Faced) |
Combine both for complete heat & moisture barrier |
| Summary & Recommendation |
For most Australian homes and sheds, combining foil & blanket insulation delivers the best thermal and acoustic results. Always install according to the manufacturer’s guidelines and use approved roofing fasteners for a secure fit. |
Pair with these products:
