The best of both worlds

  • The best of both worlds
  • The best of both worlds
  • The best of both worlds
  • The best of both worlds
  • The best of both worlds
  • The best of both worlds
  • The best of both worlds
  • The best of both worlds

Farmhouses, and indeed cottages, are full of charm. It’s no wonder therefore that they’ve inspired a great number of Irish self-builders to design their own contemporary equivalents. Existing structures, however, are another matter – their walls can often be damp and humid, and the rooms small and dark. As seen in this issue’s ROI case study, if the structure has been left for too long, sadly the best option is to demolish it. Happily, this traditional 19th Century farmhouse in Co Tipperary was brought back to its former glory, retaining its character and identity. Project architect Claire McManus of Open Architects shares the details.

This home stands on a 10 acre site, and is a typical Irish cottage: 105m2 in size, its 600mm thick stone walls exude charm and provide a great sense of enclosure. “The clients were keen to keep the character of the house but they also wanted their home to suit the way they live,” says project architect Claire McManus. “They wanted an upstairs bedroom with a view of the winter sunrise as well as a bright kitchen and sunroom facing south, to take in the views and complement the existing house. They were also very clear about the need for lots of bed spaces but not many bedrooms, reflecting the fact that the house would usually only have two occupants but would cater for many occasionally. The damp and cold were essential to eliminate as well.”

The solution was two fold – renovate the existing cottage and create an extension, which added 80m2 to the floor plan. The renovation consisted of removing the concrete render, which prevented the walls from breathing, and resurfacing with lime. The extension, meanwhile, created a bridge between the cottage and the nearby barn. As well as stables, the barn offers a 200m2 utlity for firewood, storage, washing area, coats, boots, etc. “We put in a door between the two buildings to allow the clients to check up on the horses without having to step outside – an added plus on a cold winter morning!,” says Claire. “The wall between the extension and the barn is quite interesting. We rebuilt it in stone with two doors in it: one connects the kitchen to the barn, which acts as a 200m2 utility, and the other one is halfway up the stairs to the bedroom. This provides access to the newly built bathroom that hangs in the roof of the barn.”

10_DSCN2090The clients also wanted a bath in the cottage, and it had to have a good connection to the outside. So they installed a jacuzzi bath in the old porch at the back of the cottage. “With windows on three sides, the bath takes up the entire porch space, providing both enclosure and unbeatable views,” she adds. “Only the bath fits in the porch, the rest of the bathroom – toilet, wet room, whb – is located in the main house.”

Despite the bold architectural statement made by the extension, there were no planning issues raised. “While exciting, the design fits very well with the existing one and doesn’t seek to dominate,” says Claire. “The two storey extension doesn’t exceed the height of the existing single storey barn, which was key to securing planning permission. Plus, we were building on a sloping site, so this cantilevered solution allowed us to retain the existing roof line – which is often a precondition to gaining permission to extend – and ensure that the sunroom downstairs would be flooded with light, all the while framing the views.”

The kitchen and sunroom were orientated to be south facing. “The danger with this elevation is that it can overheat, especially in a sunroom!,” adds Claire. “Walls are much better than windows when it comes to keeping the house cool in the summer and hot in the winter, which was part of the reason why we put in reinforced concrete walls shaped likes fins – for their thermal mass. They also allowed us to introduce the glazing strategically, to let the maximum amount of light in.”

The owners were also keen to have an underfloor heating system, both in the renovated part of the house and in the new build. Claire says that the decision to install a horizontal ground source heat pump hinged on the fact that they chose to restore the cottage along traditional lines: “It wouldn’t make sense to put a geothermal heating system into a passive house because you would need so little heat that it would take 100+ years to get a return on your investment. In our case we took the decision not to insulate the walls, and use wall vents. Therefore the heating requirement was such that underfloor heating and the geothermal investment made sense.” The system is complemented by a wood burning stove, to provide a boost in the winter.

“The extension was completed whilst the clients continued to live in the cottage,” says Claire. “Once that was ready, they moved into the extension and the cottage renovation began.” Overall, the design took about six weeks and construction a further nine months. Here’s some highlights of the build:

Both renovation and extension

  • Uniform roof across old and new: cottage roof completely stripped back, new slates cover both buildings (bar the cantilevered bedroom clad in corrugated steel); warm roof construction, including 250mm rockwool insulation and insulated plasterboard, yields a U-value of 0.12W/m2K
  • All windows are argon filled and triple glazed, including in the cottage; U-value of 0.7W/m2K
  • Concrete floors insulated with rigid phenolic insulation throughout; U-value of 0.09W/m2K
  • Underfloor heating throughout; ground source heat pump provides “green” and cheap heat, compensating for the cottage’s uninsulated walls

13_003-AFTERRenovation

  • Removed concrete render, which was a barrier to the moisture in the walls from getting out; also removed a concrete plinth under the old walls
  • Gave the walls four weeks to dehumidify; the walls continued to dry out after the lime render was put on
  • French drain installed around the perimeter of the house to improve drainage
  • Thick old walls were purposefully not insulated; this allows them to breathe and allow any rising damp to dry out, but also helps retain character inside and out. The walls are believed to have a U-value of about 2.1W/m2K
  • Replaced all windows and doors with hardwood frame and triple glazing
  • Old porch converted into bathroom with jacuzzi bath to enjoy views

Extension

  • The extension is built on the top of a slope and the soil was sand, so a raft foundation was needed, 300mm and deepening to 400mm under the supports for the cantilever
  • Bedroom cladding made of corrugated steel
  • Walls’ overall U-value 0.16W/m2K
  • Rockwool insulation in the cantilever wall 250mm thick, in the floor 200mm thick
  • Cantilever constructed with steel, for strength, and timber for stud walls (insulation in between studs and further insulation across studs to avoid cold bridging)
  • Form and position of the cantilevered bedroom has minimal effect on the lines of existing buildings and creates an exciting moment where house and barn ‘crash’ into each other; the bedroom is small like a tree house but a large walk-in wardrobe makes it practical
  • The upstairs (cantilevered) bathroom is “stolen” space from the barn roof; underneath it (1.2m below) is the utility room, which houses all of the geothermal machinery, washing machine, etc.
  • Conceptually the fin walls are slices of the old cottage wall; made of concrete and cast on site
  • Under a continuous roof the fin walls tie old and new together providing privacy, shade and sense of enclosure; when viewed obliquely they appear solid
  • The large gaps between each fin allows light and views; the bigger gaps in the sunroom allow more light in

Claire McManus MRIAI, Open Architects, 97 Morehampton Road, Donnybrook, Dublin 4 tel. 01 6689477, mobile 087 9047500, www.openarchitects.ie

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