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Garden Bothy, Cumnock

Garden Bothy, Cumnock

Upgrades to walls, floors, windows and door

Overview

The aims of the trials at the Garden Bothy, were to test, in situ, a range of energy efficiency improvement measures; to further demonstrate the applicability of vapour permeable materials in a traditional building and to provide a replicable whole building refurbishment case study.

A guiding principle behind the research by Historic Scotland, on various sites is that any building element being improved should maintain vapour permeability. Vapour barriers should not be created when energy efficiency fabric upgrades are being carried out in a traditional building.

It was also hoped that the building could be used as a case study for the sensitive upgrade of traditionally constructed properties. All the measures used at the Garden Bothy were executed by contractors from the local area and were reasonably straightforward to carry out. This was important as, to be truly replicable, it must be possible to source the appropriate professionals with relative ease.

Cost was also a consideration; an initial plan drawn up for the work was for over £200,000 and, had this been followed, the upgrades would have been beyond the reach of most building owners and could seldom have been replicated.

Approach

Existing Fabric

The Garden Bothy, on the Dumfries House Estate, Cumnock, East Ayrshire is a two storey building with a living room and kitchen on the ground floor and two bedrooms and a small bathroom on the upper floor. The walls are formed of sandstone rubble masonry, except from the rear elevation which is lined on the outside with brick, forming part of the walled garden.

Originally, all internal walls would have been lined with lath and plaster. This had however, been lost throughout the ground floor rooms due to previous extensive refurbishments, although it had survived more or less intact in the upper floor rooms.

A number of workshops are built onto one gable end, reaching the level of the first floor. Prior to the intervention works, the property had been suffering the effects of at least five years of inoccupation and many years of limited maintenance. This led to water ingress at several points and subsequent damage to building fabric.

 

Improvement measures

Repair works had to be undertaken to bring the property back into a good condition, before the energy efficiency works could be begun. Most of this work was related to preventing water ingress, through repairs to the roof and repointing of external walls. This work had to be completed to ensure that the refurbishment measures would not be water damaged. 

Internal insulation was installed to improve the thermal performance of the external walls. Different products were trialled at Garden Bothy:

  • Hemp insulation and clay board
  • Wood fibre insulation and clay board
  • Blown cellulose
  • Blown bonded polystyrene bead.

Sheep's wool insulation was laid in the roof space.

Lime concrete flooring was laid, with a Lightweight Expanded Clay Aggregate (LECA) insulating layer underneath.

Windows were, where possible, repaired and upgraded to double glazing. Units which were too badly damaged were replaced with new timber windows, of the same design. The external door was replaced with an insulated model which was in keeping with the aesthetics of the property.

A pellet fuelled biomass boiler was installed in the loft space to provide hot water and heat for four radiators.

Providing natural ventilation was a consideration during the refurbishment. Cost information and details of the measures taken to retain existing fabric and fixtures can be viewed in the full case study report.

Performance

Monitoring and testing is currently on-going. Results will be published when they are available.

Lessons

The work undertaken at the Garden Bothy represents a ‘whole building’ approach to sensitively upgrading the thermal performance of a traditionally constructed building.

Monitoring of moisture levels and to establish the improvement in U-values is on-going. Results will be published when the testing is complete.

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