Can I Just Insulate Between the Rafters?
We will be looking at insulating pitched roofs and why insulation just between rafters isn’t viable
Knowledge Article4 min read
The refurbishment of the former magistrates' court and carpet weaving factory in Kidderminster provides a hopeful future for the heritage building. The new business & creative hub will provide an inspirational space for local businesses and independent creatives to socialise and work. To raise the energy performance of the Victorian building, improvements were made to the building fabric including the installation of Kooltherm K118 Insulated Plasterboard and Kooltherm K107 Pitched Roof Board.
The Old Court has had a rich history, serving originally as the administrative building for one of the last carpet factories in Kidderminster, and later as a magistrates’ court. The redbrick building forms a visual gateway to the town, offering the first glimpse of Kidderminster’s centre as you approach from the railway station, but had become disused and derelict.
Following a £20.5 million investment in the town under the Future High Streets Fund (FHSF), the council chose to refurbish and repurpose the building and the adjoining weaving sheds as a creative hub which includes high quality offices, performance and exhibition spaces, social areas and a café. The transformation of The Old Court and The Weaving Sheds is intended to play a key role in the renewing and reshaping of the town’s centre.
As The Old Court building had sat disused since the mid 2000’s, careful restoration work was needed to bring the building back to life. This included an extensive programme of works to the building envelope including its large, pitched roofs. Following a careful survey it was determined that only around 30% of the existing clay tiles were sound. The roofs were stripped back and new tiles were sourced to match the originals.
LOCATIONKidderminster, UK
As part of the work refurbishing the roofs, the project team also looked to upgrade their thermal performance.
To achieve this, 70 mm thick Kooltherm K107 Pitched Roof Board was fitted between and below the roof rafters. Suitable for use in tiled or slated pitched roofs, the boards have a thermal conductivity of 0.019 W/mK. This can allow low U-values to be achieved whilst still retaining headroom within loft spaces.
The boards were carefully cut to size to fit between each roof joist, ensuring they fit snuggly within the gaps. A further layer was then fitted beneath to prevent potential thermal bridging through the joist timbers. As the boards are rigid, they will not sag over time and could be quickly and easily installed
Extensive drylining was also carried out within the main building to replace damp or damaged plaster. To upgrade the thermal performance of the external walls, whilst retaining the building’s historic appearance, Kooltherm K118 Insulated Plasterboard was fitted on the internal face of the external walls. These boards combine insulation, drylining and vapour control in a single solution, supporting rapid installation.
With a thermal conductivity of 0.019 W/mK, the boards are one of the thinnest commonly used insulation solutions for internal walls. This allowed the thermal performance of the walls to be upgraded without impacting the character of the internal spaces and with minimal loss of useable space within the building. These improvements to the building fabric should help to ensure the new offices within The Old Court can be kept at a comfortable temperature all year round whilst also limiting heating costs.
Aerial images: Wyre Forest District Council
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