Specifier Review
Insulation gives new lease of life to Cornish units in Wales

Insulation gives new lease of life to Cornish units in Wales

Social housing provider, RCT Homes, has accessed Phase 2 Arbed funding to carry out a range of improvements on 30 Cornish Units in Cwmbach, Wales, including the installation of ROCKWOOL stone wool insulation to alleviate fuel poverty issues and improve living conditions for tenants.

In the past, efforts to improve the insulation of Cornish Unit homes have foundered on the difficulties presented by the Mansard Roof design. Achieving a good fit within the timber frame using externally applied options has proved challenging. When insulation has been applied from inside this type of home, the approach taken has proved too intrusive and disruptive to the building fabric and tenants in occupancy.

Insulation gives new lease of life to Cornish units in Wales

“As fuel prices have escalated in recent years, Cornish Units tenants have struggled to keep warm,” explains Dave Challenger at RCT Homes. “We worked with ROCKWOOL to come up with an effective, easy to install solution that is set to deliver a much improved thermal performance and enhance the aesthetics of these homes.”

The RCT Homes concept focussed on upgrading the building fabric in terms of design, aesthetics and technical performance, greatly improving the living environment and the health and welfare of the occupants. The housing provider worked directly with Hirwaun-based building contractor, Thomas Holdings.

ROCKWOOL devised a tailored, envelope refurbishment solution, featuring its REDArt® External Wall Insulation System (EWI) combined with the use of ROCKWOOL FLEXI® insulation which is proving very successful.

The REDArt™ Silicone external wall insulation system used for the ground floor of the Cornish Units on this scheme offers outstanding thermal and weather protection, achieving a U-value of 0.26 W/m3K, as well as an attractive exterior appearance. It comprises a ROCKWOOL REDArt™ Silicone 100mm slab of stone wool insulation which is mechanically fixed to the existing substrate. A ROCKWOOL FS Mortar 2 base coat was then used to apply a reinforcing layer with a top coat of REDArt™ render applied in a cream coloured, silicone finish to complete the project.

For the first floor, the existing tiles were removed to allow for the application of 50mm thick ROCKWOOL FLEXI®. This multi-use, dual purpose thermal and acoustic insulation solution was fitted between the timber rafters and frame of the Mansard roof, allowing for a 25mm gap at high level and a 50mm gap at low level for ventilation. A new breather membrane has been applied to the rafters, with battens refitted and new tiles installed. ROCKWOOL has also supplied insulated soffit and fascia boards to limit the cold bridge at the ridge beam which separates the first floor external wall from the Mansard roof.

“The ROCKWOOL insulation is performing above and beyond our expectations on this project,” comments Dave. “Working with a renowned difficult housing design, and with no previous or similar insulation refurbishment plan available, ROCKWOOL provided us with a fresh technical approach to insulate these houses, but retaining their unique style and appearance. It saves installation time and is helping to make these Cornish Units thermally efficient for tenants today and subsequent generations.”

ROCKWOOL Technical Support was on hand throughout the project to provide guidance and advice, checking work and regularly training contracting staff to ensure the REDArt® external wall insulation and ROCKWOOL FLEXI® were applied correctly, both from a technical and aesthetic perspective.

For more information on the project, please watch ROCKWOOL’s short video


All ROCKWOOL videos and further information can be found online at www.rockwool.co.uk.