Spray foam insulation from Huntsman Building Solutions has been used in the transformation of a collection of derelict industrial buildings into a stunning, architect-designed self-build home in rural Cumbria.
The buildings dated back to the late 18th century and once formed a mill producing blacking, a material used to coat the insides of casting moulds for a range iron goods, made at a nearby foundry.
Architect Robert Glass and his partner Ruth Grimshaw who now practice at Tape Design in Ulverston, had decided to move back to the South Lakeland area of Cumbria following years in the city. Robert had known about the site since his early 20’s and had always wanted to build a home there. In January 2015, they approached the owner and after finally gaining planning approval, bought the site in November 2017.
The site was challenging with narrow, single-track access. A fast-flowing beck which originally provided power for the mill ran through the site and the surrounding land was completely overgrown, almost reclaiming the tumble-down stone structures that had laid abandoned since the 1950’s.
None-the-less, the potential was clear to Robert and Ruth and plans were drawn up to transform the buildings into one stunning, four-bedroom home of 218sqm with a further 90sqm of workshop and office facilities. A 90sqm roof terrace was incorporated into the main house structure, providing recreational space and views over the surrounding woodland canopy.
High performance insulation to minimise heat loss
A key criterion in the construction of the buildings was control of the internal environment to minimise heating costs, so achieving a high degree of air tightness and the incorporation of a mechanical ventilation and heat recovery system into the finished structure was required.
It is estimated that around 40% of a building’s heat loss is caused by air leakage – essentially draughts – so an insulation system that works to prevent air leakage, effectively creating a sealed environment was essential in order to minimise heat loss.
Following detailed research, an open cell spray foam insulation solution from Huntsman Building Solutions was chosen. Their H2 Foam Lite product not only promised outstanding levels of air tightness and thermal efficiency but also allowed the building to “breathe” and move with the timber framed inner structure.
Huntsman supplies its products exclusively through a trained and authorised contractor network and the spray foam installation was handled by Preston based contractor Heatlok Insulation.
Greg Raby of Heatlok explained that HBS spray foam insulation systems were developed in Canada to cope with their severe winters and are now widely used in the UK in both the residential and commercial sectors.
He also explained that spray foam insulation is an inherently elastic material so it moves with the building without cracking and causing gaps. It’s also able to fill the small voids in the structure where conventional rigid board insulations are almost impossible to fit effectively.
Minimal environmental impact
Unlike the urethane foams of 20 years ago, modern spray foams such as HBS H2 Foam Lite uses water as the blowing agent. This means that the reaction between the two components produces a small amount of CO2 which causes the foam to expand. Cells of the foam burst and the CO2 is replaced by air.
According to Huntsman Building Solutions, H2 Foam Lite E is currently the only spray foam insulation system to carry the prestigious BBA Certification.
From an environmental perspective, H2 Foam Lite claims a Global Warming Potential of 1 and an Ozone Depletion Potential of 0 . Furthermore, it doesn’t emit any harmful gases once cured, another important factor in the choice of insulation. “Ruth is very sensitive to chemicals in the air, the fact that H2 Foam Lite is becomes inert after a few seconds, with little or no off-gassing after installation, made it the perfect choice for us” said Robert Glass.
Thermally efficient structure
H2 Foam Lite was used in the external wall and roof areas to create a highly thermally efficient structure. External walls are a combination of 250mm outer leaf of Lakeland stone facing with 140mm thick timber frame inner leaf with spray foam filling. Inner 50mm thick battening allowed an extra 90mm thickness of foam insulation giving an overall thickness of wall insulation of 230mm.
Where timber cladding was used to visually soften the exterior appearance, wall sections comprised 22mm thick larch cladding, facing a 140mm thick timber frame supporting structure with foam insulation infill. Similarly, 50mm thick inner battening allowed an extra 90mm thickness of foam insulation giving an overall thickness of wall insulation of 230mm.
Roof areas also received high level of insulation. Pitched roof areas are timber clad over a glass fibre water-proofing layer that overlays 18mm OSB fixed to 145x50mm rafters with foam infill. Foam filled 50mm thick inner battening gives an overall thickness of insulation of 230mm. Flat roof areas beneath the roof terrace received additional treatment with 300mm thick foam sprayed around the perimeter where the roof and walls meet, to fully seal any potential gaps.
Robert and Ruth acted as both designers and main contractors for the reconstruction process, a huge task whilst continuing to run their Architectural Practice, engaging and managing trades as required over the Covid disrupted build programme.
Grand Designs project
The mill transformation began in January 2018 and is due to be completed in the spring of 2022. The four-year project was the subject of a Channel 4, Grand Designs programme lead by Kevin McCloud and was broadcast in autumn of 2021.
For more information on Huntsman Building Solutions visit www.huntsmanbuildingsolutions.co.uk
For more information about HBS H2Foam Lite products: https://huntsmanbuildingsolutions.com/en-GB/products/open-cell-insulation