FAQ's
Q1: Does RainScreen Duo Slab need to be installed with a specific cladding to achieve this performance?
A: No. The testing was completed without cladding present, replicating the worst-case condition where wind pressure is applied directly to the membrane and insulation. In real-world installations, the cladding layer adds additional structural support and protection, meaning actual performance is often superior to the tested scenario. This conservative approach gives specifiers confidence that the product performs reliably across different facade designs. However, correct installation following manufacturer guidance — including proper breather membrane and mechanical fixing — is essential to achieve these results.
Q 2: How does the 50mm vs 70mm fixing result affect my specification?
A: Our testing proved that RainScreen Duo Slab successfully withstands Category 4 hurricane conditions with 50mm fixings in steel-frame cladded applications. This is significant because it gives architects and contractors flexibility on site: when space constraints prevent 70mm fixings (e.g., in retrofits with limited cavity depth), you can confidently specify 50mm fixings without compromising wind-load performance. This flexibility can reduce costs and simplify installation logistics, making the product more practical for challenging refurbishment projects.
Q 3: What does "minimal degradation" mean in the test results?
A: The tested samples showed only slight embedding (pressing) of the metal washers into the stone wool surface — a minor cosmetic effect with no structural consequence. There was no significant structural damage, no loss of dimensional stability, and no reduction in thermal or fire performance. This demonstrates that the product’s internal structure remains intact and functional even after extreme wind cycles spanning a simulated 50-year design life.
Q 4: How does this testing compare to other rainscreen insulation products available in the UK?
A: Wind-load testing is common in the UK rainscreen insulation market, but test programmes vary significantly in how closely they replicate real-world conditions. Our approach is distinguished by:
- Testing with a breather membrane present — replicating actual facade design (most tests omit this)
- Testing common UK build-ups — steel frame with 50mm and 70mm fixings, masonry facades with ACS channels
- Independent testing to BRE Digest 346 — the industry standard for wind-load assessment
- Transparent reporting of test conditions — you can review the exact build-up tested, not just the final rating
This transparency allows you to verify that the test reflects your intended specification, reducing project risk.
Q 5: Does this testing cover all ROCKWOOL rainscreen products, or just RainScreen Duo Slab?
A: This testing specifically covers RainScreen Duo Slab in 125mm thickness, tested in the configurations detailed in our results table (steel frame with 50mm/70mm fixings, and masonry facades with ACS channels). Other ROCKWOOL rainscreen products such as NyRock RainScreen 032 have also been hurricane force tested. Product performance data may differ, please consult the relevant product datasheet or contact our technical team to confirm performance for alternative products or thicknesses.
Q 6: What is BRE Digest 346, and why does it matter?
A: BRE Digest 346 is the industry-standard procedure published by the Building Research Establishment for assessing wind loads on building facades. It's recognised across the UK construction industry and specifically addresses wind speeds, test cycles, and pressure categories aligned with real-world exposure. By testing to this standard, we ensure the results are credible, comparable, and relevant to UK building design practices. You can specify with confidence knowing the test follows established, independent methodology.
Q 7: How do I verify that RainScreen Duo Slab meets Building Regulations for my specific project?
A: Our technical team can review your specification in advance and confirm compliance with Part B (Fire Safety) — RainScreen Duo Slab is Euroclass A1 rated — and help address any other regulatory questions. For wind-load requirements, this Category 4 hurricane testing provides robust evidence of performance under extreme conditions, exceeding typical Building Regulations exposure assumptions. Contact our technical support team with any queries you may have:
Email: technical.solutions@rockwool.com
Telephone: 01656 868 490
Q 8: What maintenance or re-testing is required after installation to maintain this hurricane-force performance?
A: ROCKWOOL stone wool's non-combustible mineral structure is inherently durable and does not degrade over time up to and over 50 years,, when properly installed and maintained. The 50-year design life assumes normal exposure and maintenance of the facade system (e.g., keeping drainage clear, inspecting fixings annually as part of routine facade care). Re-testing of the installed insulation is not required if the original installation follows manufacturer guidance. However, if the facade system is modified significantly (e.g., cladding replaced, fixings altered), consult our technical team to confirm performance implications.
