Stour Homes, a family-run housebuilding company based in Dorset, has specified Vario XtraSafe – Isover’s new ‘smart’ airtightness and moisture management system – for an ambitious residential project in Wiltshire.
The 1,200m2 premium timber frame property is located in the picturesque area of Limpers Hill and will have five bathrooms and bedrooms. It is expected to be completed by Christmas 2017 and is being built with both airtightness and moisture management in mind.
At the Limpers Hill project, the Vario XtraSafe system, with its ground-breaking smart-membrane, was specified instead of the more traditionally used polythene vapour control layers (VCLs). This meant the structure was able to benefit from an airtight finish while avoiding the adverse effects of moisture build up.
Vario XtraSafe is made from a breathable nylon layer with variable resistivity properties. The solution is considered to be three times stronger than polythene and has an Sd value ranging from 0.3m – 25m. This means it can actively adapt to the moisture conditions within the building fabric, providing the best possible protection for the building structure throughout the year.
In winter, when it’s cold and damp outside, and warm and moist inside, the relative humidity in a wall is low, so Vario’s pores will close to keep water vapour away. Conversely, in summer when it’s warmer outside, the membrane will open its pores to allow any accumulated water vapour to flow out, so the structure can dry.
Eddie Hudson, one of Stour Homes’ business owners, and a master carpenter, commented: “As anyone involved in housebuilding will tell you, what makes the difference between a house and a home can be as simple as the materials we use to build them.
“For this project, we wanted to achieve an EPC rating of at least B, which meant reaching an airtightness value of around 5 m3/h.m2 @50 pascals. By using Vario XtraSafe, we were able to exceed this level and meet our target.
“Vario XtraSafe was also really quick and easy to install, so we were able to remain on schedule and achieve the required airtightness levels during the build.”
Airtightness refers to the amount of air that can escape or enter a building uncontrolled through unwanted gaps, cracks or drafts. In the UK, new residential dwellings are required to meet strict Building Regulations for airtightness. Part L1A (England and Wales) and Section 6 (Scotland) sets out the minimum requirements in order to improve the energy efficiency of all new homes.
By ensuring a building’s airtightness levels exceed current regulations developers can help homeowners achieve considerable financial savings by preventing the loss of heat and energy over time.
Managing moisture effectively is another vital component within residential builds, especially in timber frame properties. Failure to address moisture accumulation can lead to long term damage in the structural integrity of the building.
In addition to Vario XtraSafe, Stour Homes chose to specify Isover’s Acoustic Partition Roll (APR 1200) for the internal walls of the project and Timber Frame Roll 32 insulation for the external walls.
Eddie commented further: “With the current market volatility around PIR insulation pricing and availability issues, Timber Frame Roll 32 provided an ideal replacement for us.
Sarah Buchanan, Product Manager, at Saint-Gobain Isover, added: “As fuel costs continue to rise, prospective homeowners are looking for more energy efficient properties. At the same time, ensuring higher levels of general wellbeing in living spaces is another factor being increasingly considered.
“Vario XtraSafe is one of the most intelligent vapour barriers on the market. Its one-man installation capability means it also makes installers’ lives much easier and helps reduce costs for housebuilders. The solution comes with an innovative fixing system that enables faster and more efficient installation when compared to traditional VCLs.
“Once built, Limpers Hill will be a beautiful, high performance residence for the owners and we’re delighted our products will be playing their part, helping ensure a comfortable living space.”
For more information about Isover’s Vario XtraSafe airtightness and moisture management system, please visit https://www.isover.co.uk/vario.
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