Knauf Insulation fulfils its promise

Knauf Insulation is launching new products to fulfil its promise of providing straightforward insulation solutions to help the industry meet the new, 2006 version of Part L of the Building Regulations. Two of the products – DriTherm® 32 and DriTherm® 34 Cavity Slab – have been eagerly awaited as they are one of the company’s recommended solutions for full-fill cavity wall insulation. The new products ensure that, despite fears about the design implications caused by the changes to Part L, cavity widths can remain at 100 mm or less.

The benefits of full-fill cavity wall insulation are well known and, if either glass or rock mineral wool are used, hard to resist. Full-fill cavity wall insulation is quicker and easier to install than part-fill insulation as the fixings used to hold the material against the inner leaf and create a residual cavity are not required. Mineral wool slabs can also offer a better thermal performance as the ‘give’ in their surface overcomes minor imperfections on the face of the cavity and their edges mesh together, closing joints and preventing cold bridging. In cavities using rigid board part-fill insulation, snots of mortar can force the boards away from the surface of the inner leaf creating air gaps behind and through the insulation. (In fact, a DETR report published in 2001 noted significant variations between the measured and calculated U-values of part-fill cavity wall insulation – even across the same wall!). Mineral wool has excellent acoustic and fire insulation properties which means that, when used as full-fill cavity wall insulation, it also provides an effective acoustic, and fire stop. Knauf Insulation’s product range offers solutions for either new-build or existing walls. In new-build construction, semi-rigid slabs are simply placed in the wall’s cavity as it’s built. Crown® DriTherm® Cavity Slab and Rocksilk® DriTherm® Cavity Slab are semi-rigid slabs of glass and rock mineral wool specifically designed for use as full-fill cavity wall insulation. Measuring 1200 mm long by 455 mm wide (for use with wall ties at a vertical spacing of 450 mm) they are available in a range of thicknesses to maximise design versatility. Existing walls are insulated by dry-injecting loose mineral wool through holes drilled in one of the leaves – this also offers designers an alternative method for new-build construction. Crown® SupafilTm Cavity Wall Insulation is a loose, glass mineral wool insulation installed by approved contractors using specialist equipment.

“Experience shows that full-fill cavity wall insulation is, in theory and reality, the least expensive and most cost-effective method of insulating a cavity wall,” said Stephen Wise, Knauf Insulation’s Market Development Manager for the residential sector. “We’ve promised to provide straightforward insulation solutions to help the industry meet or exceed the targets required by the changes to the Building Regulations and, now we know what we’re aiming at, we can fulfil that pledge!”

The new regulations coming into force on 6 April 2006 focus on ‘whole-building’ performance and aim to increase energy standards by between 18 and 27 per cent in new buildings. Although there is flexibility in exactly ‘how’ this is achieved, any shortfall in performance in one variable has to be compensated for elsewhere. The new products are specifically designed to give designers a flying start by ensuring that Elemental U-values between 0.27 and 0.32 W/m2K can be achieved in cavity widths of between 75 mm and 100 mm.

For further information, please visit Knauf Insulation’s website at or call their enquiries hotline on 08700 668 660 quoting CR 421 05.

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