Upgrade to high-performance insulation with the Rockwool Flexi 140mm acoustic slab — designed for premium acoustic, thermal and fire-safety applications. With a thickness of 140 mm and standard board dimensions of 1 200 mm × 600 mm, each pack typically covers ~2.88 m².

This product features the patented FLEXI Edge® technology, ensuring a tight friction-fit between timber or metal studwork. That means fewer gaps, better sound isolation and improved insulation integrity — even if timber shrinks or frames settle over time.

From a thermal standpoint, it delivers a lambda (λ) value of 0.035 W/m·K at 140 mm thickness. The slab also carries the highest fire-safety classification of Euroclass A1 (non-combustible) under BS EN 13501-1, which means it won’t burn or contribute to fire spread — a key selling point for spec-heavy builds.

Installed correctly, the slab excels in separating partitions, ceilings, floors, roof build-ups and timber-framed external walls — especially where acoustic performance and fire safety matter. The semi-rigid stone-wool build means it’s easy to handle, trim and install, and stays effective for the lifetime of the structure.

Whether you’re specifying for multi-residential flats, commercial office partitions, refurbishment projects or new builds where build depth allows — the Rockwool Flexi 140 mm slab gives you a top-tier solution: thick enough to push acoustic and thermal performance, trusted brand behind it, and built for installers.

Key Features

• Thickness: 140 mm — deep build-up for enhanced acoustic & thermal effect

• Dimensions: 1 200 mm × 600 mm board size

• Pack coverage: ~ 2.88 m²

• Thermal conductivity (λ): 0.035 W/m·K at 140 mm thickness

• Fire classification: Euroclass A1 (non-combustible)

• Material: Stone wool (rock mineral wool) — durable, dimensionally stable, water-repellent

• Patented FLEXI Edge® for secure fit between frames, reduces waste and improves install speed

• Application range: Internal partitions, separating floors & ceilings, timber/metal stud walls, frame external walls, roof build-ups

• Installation: Semi-rigid slabs, easy to cut and fit, designed for high performance and long-term reliability