Product Description:

Knauf Loft Roll 44 Combi-Cut is a flexible glass mineral wool insulation roll, 200mm thick and covering 5.5m². It is used for thermal insulation of pitched roofs at ceiling level, laid between and over ceiling joists, and is equally suitable for insulating suspended timber floors.

The Combi-Cut format is what makes the roll quick to work with in a loft. It is partially cut along its length so it can be separated by hand into narrower widths to fit between standard joist centres, or left whole and rolled out full width across the joists for the top layer, which removes most of the cutting from the job.

The 44 designation refers to the material's thermal conductivity of 0.044 W/mK, which at 200mm gives an R-value of around 4.55 m²K/W. This is the thickest roll in the range, and it is chosen either as a generous top layer over 100mm between the joists, giving 300mm in total and exceeding the 270mm currently recommended, or as a single deep layer where joists are unusually deep. Laid across the joists at right angles, the top layer covers the timbers themselves and removes the cold bridging that would otherwise run through them. Glass mineral wool is lightweight, resilient, and non-combustible, and sits snugly without slumping or leaving gaps. Wear gloves, a dust mask, and long sleeves when handling, keep the insulation clear of downlighters and flues, and do not block eaves ventilation.

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