Official figures show that over 60 per cent of our current housing stock was built pre-1960 when little thought was given to heat loss prevention. So, when forward-thinking design practise CASA Architects, was commissioned to oversee the renovation of two historic buildings near their base in Bath, high performance insulation and reduction in CO2 emissions was high on the agenda.
The two properties could not be more different in architectural style and location:
One, the complete refurbishment and extension of an architecturally significant Edwardian Terrace house in the heart of Bath; the other, the renovation of an early 19th Century farmhouse/barn in rural Wiltshire together with the conversion of an adjacent, Grade 2 listed cow byre.
CASA project Architect, Matt Hanna explains,
“The Edwardian Terrace property was a significant refurbishment and extension and our client required exceptionally high environmental standards, with internal insulation, triple gazing, rainwater harvesting and so on. Being a terraced house, the client also wanted acoustic separation to the party walls so high-performance sound insulation was essential.”
CASA’s solution involved the construction of 75mm thick internal timber studwork, spaced 10mm off the solid stone internal and party walls. Spray foam insulation from specialist supplier, Icynene was then applied directly to the exposed stone-work, followed by a proprietary vapour check membrane and plaster-boarding.
Spray foam insulation
Icynene is a high performance, spray foam insulation applied using a pressurised gun system. Foams are sprayed as a two-component mixture that come together forming a foam that expands 100-fold within seconds of application, sealing all gaps, service holes etc
According to Icynene, traditional forms of insulation are relatively inefficient in creating a “sealed box” environment, in that they cannot completely fill all voids or seal the interface between the insulation and the building structure. Nor can they cope with small structural movements which will often lead to air gaps.
Minimising air leakage is one of the most effective ways of reducing heat loss in a building, as up to 40 per cent of a building’s heat loss can be attributed to air leakage.
For the barn and byre conversion, a similar studwork treatment, 95mm thick, was applied to external rooms of the barn. Icynene was also used to insulate the roof of the cow byre. Here, additional timber battens were applied to increase the thickness of insulation while still allowing exposure of the original timber roof structure.
WUFI modelling
Matt Hanna continues;
“For both projects, we engaged environmental consultants to run WUFI, hygrothermal modelling tests on our proposals”.
WUFI is a computer program that can show how moisture and heat flow affect building materials over time. He added,
“The results showed that Icynene was the right product to use.”
Icynene Foamlite LD-C 50 insulation was used on both projects. Foamlite is a “vapour open” material that allows moisture vapour to pass freely through it, allowing the building to breathe naturally, resisting cold bridging and condensation.
Unlike the urethane foams of 20 years ago, modern spray foams such as FoamLite use water rather than environmentally damaging petrochemicals as the blowing agent. This means that the reaction between the two components produces C02 which causes the foam to expand.
As the foam expands, the cells burst and the CO2 is replaced by air. Consequently, from an environmental perspective, Icynene has a Global Warming Potential of 1 and an Ozone Depletion Potential of 0 . Icynene does not, therefore emit and harmful gases once cured.
Rapid installation
Icynene installation contractor, Heatlok, undertook the work on both projects, with spraying completed within a day for the terraced house and roughly three days for the farmhouse and barn. It has been estimated that, if conventional rigid board type insulation had been used on the projects, installation would have taken significantly longer and with less efficient results.
Since completing the Bath Terrace and Wiltshire Barn projects, CASA has gone on to use Icynene on further schemes where high performance:low environmental impact are influencing factors in the construction solution.
Matt Hanna says,
“CASA’s name embodies our approach to design and construction. We aim to create Contemporary and Sustainable Architecture, hence the name (CaSA) and we work incredibly hard to give our clients the best solution with the lowest practical environmental impact”.
Images courtesy of CaSA Architects.
For more information on Icynene:
CASA Architects: www.casa-architects.com
Installation Contractor – Heatlok: www.heatlok.co.uk