HardRock® Multi-Fix (DD) Underlay Slab
Thermal and acoustic insulation for flat roofs.
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Application(s)
- Roof
- Flat Roof
Product description
Designed to be installed with HardRock® Multi-Fix DD, HardRock® Underlay is a vital component in a ROCKWOOL flat roof solution. Manufactured from non-combustible stone wool, this robust product offers a thermal and acoustic foundation for a insulated flat roof system.
*Subject to application
- Euroclass A1 in accordance with BS EN 13501-1 Reaction to Fire rating
- Thermal conductivity 0.039 W/mK
- 70kPa Declared Compressive Strength
- Up to 120 minutes of fire integrity and insulation*

HardRock Multi-Fix (DD) Datasheet
HardRock Multi-Fix (DD) is a BBA-approved dual-density insulation board suitable for various surfaces, including flat roofs. In addition to thermal comfort, it provides independently tested acoustic and fire resistance properties.

SUIS ROCKWOOL UK
Safe use instruction sheet ROCKWOOL stone wool insulation products

Republic of Ireland Price List
Price List March 2025

UK Price List
Price List March 2025
Hands-on fire-stopping training
ROCKWOOL’s specially created expert led one-day course in fire stopping theory and practical installation practice for industry professionals.
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