Isover insulation system can cut housebuilding costs by 20%

Saint-Gobain Isover launched RD35 (E-WM-8) in 2005 as a response to the requirements of the new Part E Acoustic Regulations which required a Robust Detail–approved system to avoid pre-completion sound testing.

Regional housebuilder Macbryde Homes, who were one of the first developers to adopt this construction method, were able to finish developments days ahead of schedule and were so impressed with the savings it is now their standard method for party wall construction.

Macbryde’s design director Ian Hornby said. “Isover’s RD35 system can be installed in all temperatures, in a fraction of the time a parge coat takes, and without the mess and labour involved when using wet cement. And because it’s manufactured from 80% recycled material, it’s vastly more environmentally friendly than cement.”

Now research by Isover shows cost savings of more than 20% can be made in materials and labour because the party wall does not have to be plastered on both sides. Neither does the contractor have to wait for the parge coats to dry – another time saving.

The basic wall construction of E-WM-8 also ensures one credit under the Code for Sustainable Homes, while increasing the design cavity to 100mm attracts three.

Gerry Mitchell, Isover’s head of innovation, said: “Housebuilders’ revenues and profits are falling and they are seeking ways to work with their suppliers to cut costs and minimise the impact. Here we have the cheapest masonry wall Robust Detail construction which can save around 20% compared to other solutions.”

All other Robust Detail masonry party wall constructions force housebuilders to revert to a wet trade internal wall lining, generally involving sand and cement, away from the plasterboard-on-dabs method that had been their preferred one for years.

Isover RD35 high-performance acoustic slabs are positioned in the party wall cavity in conjunction with plasterboard-on-dabs dry lining, allowing housebuilders to revert to their preferred method of construction. It is the only Robust Detail-approved alternative to cement-based solutions. As such, it has attracted tens of thousands of plot registrations to date.