Dry Gap Farm Barn sits in an exposed position on the Pennine moors, and presents a modest exterior typical of isolated Pennine farmhouses. Inside, however, it is a gem of regional vernacular architecture, with three complete cruck trusses and other features that have remained largely unchanged since the sixteenth century, although the rafters themselves were installed last century.
Conversion into living accommodation has been slow, with archaeological and bat surveys carried out in 2009, along with a structural report. As a Grade II Listed building it is exempt from the insulation requirements of the Building Regulations, however, the perceptions of what constitutes adequate insulation have since shifted, so the owner was looking for a way to maximise the efficiency of the insulation buildup for his rafter depth.
It was decided that BBA Approved TLX Silver Multifoil Insulation (Certificate 06/4379) would help ensure a warm interior for the occupants within a barn subject to the extremes of the North Pennine weather.
TLX Silver was used beneath 80mm of foiled rigid board insulation, achieving a U-value of 0.19 W/m2K. A condensation risk analysis was carried out by the TLX Technical Helpline staff to check that the recommended solution was suitable. Stapled to the underside of the rafters, it was secured with a 38mm crossbatten (which minimises the thermal bridging as the multifoil is only compressed where the battens cross). It also created unventilated air gaps above and below between them, which, because of the very low emissivity surfaces of TLX Silver (Ɛ=0.05), minimises heat transfer by radiation.
The result was a building retaining its authentic features, with a snug interior and an exterior still suitable as a home for bats.