A warm outlook in Perthshire

John and Katie Langley found the perfect structural solution for adding a substantial, energy efficient extension to their traditional Scottish farmhouse


ohn and Katie Langley, who have a construction business in Scotland, bought their 80-year-old farmhouse in rural Perthshire in 2004, just after they got married. A traditional stone built property sitting in an acre of land, the couple fell in love with it straight away. Not only were they looking for a family home in Perthshire, they also saw the potential for converting the outbuildings into a holiday cottage and offices to use as the base for their housebuilding and engineering firm, JML Contracts. After two years in the farmhouse and the arrival of their first son (and expecting their second), John and Katie decided that now was the time to undertake a serious extension, and increase not only the amount of bedrooms, but also the liv- ing space needed for their growing family. Katie reflects on the decision to extend: “We immediately fell in love with this house for so many reasons, including its location, traditional stone built archi- tecture, and the ability to create addi- tional revenue by using the outbuildings. However, given its reasonable age there were the accompanying draughts, lack of appropriate insulation and space limita- tions for a modern family.

She continues: “Our business spe- cialises in building with Structural Insulated Panels, or ‘SIPs’. Until this point we had only worked on newly built prop- erties constructed in SIPs, but with our knowledge of the product and also the help of a specialist architect (Kerry Smith) we decided that this would be the ideal technique for our extension”. The couple wanted a modern layout and a much more thermally efficient home which would reduce their energy bills. “However,” says Katie, “we still wanted to maintain its traditional look and for it to appear as a seamless

22 january/february 2018 continuation of our home”.

After they finished the conversion of the outbuildings, they decided to move into the cottage while they carried out the extension works. ”This was ideal as it meant we were on site to oversee works and could ensure that our schedule was met. The imminent birth of a second child was a very good driver for sticking to schedule!”

Katie continued: “Our extension plans were ambitious as we planned to double the size of the original house. However, as housebuilders we knew that the major- ity of the cost of an extension is in its foundations so it made sense to us to build above and create as much extra liv- ing space upstairs as downstairs. We knew we had to move out of the house to carry out the works, so we decided the only way to do it was all at once!” Kerry Smith Architects are based not far away in Angus, and the couple briefed the architect to design an exten- sion which included all the extra living space desired, was in keeping with the house’s original architecture but which

would be built in SIPs so that Katie and John could have the cosy, thermal efficient living space they longed for. The double storey extension took the house from approximately 180 m2

to 360 m2 .

The design included a huge kitchen- diner, a downstairs WC, spacious boot room (essential for country living!), and laundry room accessed by a new back door and hall. Upstairs two new double bedrooms, a master bedroom, en suite and dressing room were added. The whole extension was built with SIPs using high quality sustainable materials. It took a year to build from start to finish, and the super-efficient insulation means the house is warm but also not susceptible to draughts from the sometimes inclement Scottish weather!

Building with SIPs also meant that extra height could be achieved in the bed- rooms upstairs as it removes the need for roof trusses. As a result the bedrooms were not only cosy – the vaulted ceilings also provided a more spacious feel. It also meant the construction process was quicker as the SIPs panels are all manufactured offsite. It was a tricky erec- tion process on site, as adding a SIPs extension to an old existing building meant that all measurements and draw- ings had to be precise. However it was only 10 days before the skilled SIPs team had erected the extension and made it watertight ready for the next stage. The walls and roof are all SIPs panels making a very strong and thermally efficient external envelope. The U-values and air tightness are well above other construction methods, and as a result the thermal efficiency is really impressive. However proper ventilation had to be ensured as a result, as Katie explains: “We were very keen to ensure that the space was properly ventilated and we installed an HRV (heat recovery

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