Buying the 200mm Knauf Loft Roll 44 Combi-cut in bulk makes sense on projects where the aim is to drive heat loss as low as it will go, as the thickest roll Knauf offer in this range. Worked over a 100mm base layer between the joists, it lifts the total depth to 300mm, comfortably past the 270mm used to meet the 0.16 W/m²K roof target under Part L of the Building Regulations. Push it further with two 200mm layers cross-laid over the base and the total reaches 500mm, dropping the U-value to roughly 0.09 W/m²K, the standard of insulation you'd expect to find specified in a new build. It's intended for cold pitched roofs at ceiling level, and is equally at home between joists in suspended timber floors.

Performance sits at 0.044 W/mK thermal conductivity with a thermal resistance of 4.50 m²K/W, the highest in the range, and as a glass mineral wool it carries a measure of acoustic absorption too, quietening airborne sound through the ceiling. Each roll is 1140mm wide by 6.00m long, giving 6.84m² of cover, and the combi-cut perforations split it to 2 x 570mm or 3 x 380mm for standard joist centres, or leave it whole for a full-width cross-laid run with little waste. The extra thickness still handles easily: light to carry up into the loft and quick to cut, well within reach of a capable DIYer as much as a trade crew.

It's made with ECOSE® Technology, Knauf's bio-based binder, so there's no added formaldehyde or phenol, it's CFC & HCFC free, and it carries zero ozone depletion potential, with up to 80% recycled glass in every roll. Rot proof, odourless & non-hygroscopic, it won't draw vermin or feed mould, fungi or bacteria, and it lasts the life of the building. A dependable choice for retrofit & new build projects where thermal performance is the priority.

Benefits

• Buying in bulk offers better value on larger projects and helps keep material costs down
• The thickest roll in the range, ideal for maximising loft performance and future-proofing the specification
• Thermal resistance (R-value) of 4.50 m²K/W for the 200mm roll, the highest in the range
• Thermal conductivity of 0.044 W/mK for reliable, effective thermal performance
• Euroclass A1 non-combustible: the best possible fire classification, meaning the product does not burn
• Combi-cut format, partially perforated at 2 x 570mm & 3 x 380mm to suit standard joist centres
• Also suitable as a primary single layer between joists, or in suspended timber floors
• Lightweight, low-itch & easy to handle on site
• Manufactured with ECOSE® Technology, a bio-based binder with no added formaldehyde or phenol
• Made with up to 80% recycled glass content: CFC free, HCFC free, with zero ozone depletion potential
• Rot proof, odourless & non-hygroscopic: will not attract vermin or support mould or fungi
• BRE Green Guide rating A+

Good to know

• Each roll covers 6.84m²
• 100mm base plus a 200mm cross-laid layer gives 300mm total, for a U-value of approximately 0.14 W/m²K, beyond the 270mm Part L standard
• 100mm base plus two 200mm cross-laid layers gives 500mm total, for a U-value of approximately 0.09 W/m²K, the level typically specified in new build
• Thickness: 200mm; width: 2 x 570mm or 3 x 380mm; length: 6.00m
• Thermal resistance: 4.50 m²K/W; vapour resistivity: 5.00 MNs/g.m
• Keep insulation clear of downlights & other heat-producing fixtures, using non-combustible covers where required
• Store indoors, dry & flat; protect from prolonged sunlight & moisture
• Always refer to the Knauf Loft Roll Installation Guide before installation