A system that was developed by the Monarfloor Acoustic Systems division of Icopal has been approved by Robust Details as the first four-credit separating wall solution for the Code for Sustainable Homes.
Bridgestop (E-WM-19) is an innovative and easy to install acoustic system that isolates the two skins of cavity party walls, preventing an acoustic bridge by the collection of mortar at the base of the cavity – the key cause of acoustic test failure.
It also isolates the party walls from the concrete sub-floor, eliminating acoustic flanking, and where used with a methane or radon barrier ensures the integrity of the barrier from possible damage from mortar droppings.
Its four-credit accreditation is significant news for the housebuilding industry seeking Code credits under Section 7: Health and Well-being, as well as recognition of Icopal’s market-leading innovation in building acoustics and commitment to developing robust and sustainable products that also offer cost savings.
Bridgestop’s properties have high acoustic damping to absorb more sound energy and reduce structural flanking, performing approximately 4-5dB better than solid walls and 8dB better than standard Robust Detail E-WM-4 walls. National housebuilder Gladedale have already achieved 53dB (mean value) – a four-credit solution – on one of their sites via this method.
Research by Icopal has also shown cost savings can be made in materials and labour because the party walls only require plasterboard of 8kg/m²instead of 12.5kg² for solid Part E solution walls, saving 4.5kg/m² of gypsum-based board per m². Time is also saved through easier detailing for step and stagger constructions.
The Roger Bullivant Group, one of the largest foundation engineering companies in the UK, has demonstrated additional benefits when clients specify the Bridgestop system along separating walls used in conjunction with their precast foundation system.
The isolation of the separating wall at ground floor level allows the foundation to be installed higher out of the ground than that for a separating wall being built to the Robust Detail alternative with a 225mm cavity below ground floor.
Roger Bullivant chief engineer (house foundations) Nigel Rake said: “When the developer is using Bridgestop, the savings alone from the supply and installation of the reduced underbuild, which can be as much as £22 per metre, would more than cover the cost of the Bridgestop system at £15 per metre.
“Also, depending on the number of separating walls, there can be significant additional cost and time savings from less excavation and spoil, and being able to offer a less complicated foundation solution.”
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