You wouldn’t know to look at it now, but few projects have had a less promising start than this listed barn recently converted by Mason Gillibrand in the Lune Valley. A storm in 2012 brought part of the roof down, destabilising the existing walls and leaving the building in a precarious state. As part of the necessary conservation works to the building,
Mason Gillibrand gained planning permission for a dwelling. The walls were rebuilt while the roof was still in place, and before jacking the trusses horizontally back onto the new realigned walls, the building had to be insulated using lime plaster.
In this instance we used a product which has only recently been developed, a hemp lime insulating plaster applied to the interior of the stone walls. Insulating existing buildings is difficult at the best of times, as it is very easy to cause condensation within the fabric of the building, and, if vapour barriers are used, moisture can build up over a period of years, causing deterioration on the longer term.
The solution here was to insulate to a minimum level on the interior, but use lime plaster and mortar throughout the rebuilding of the exterior walls, thus allowing any moisture building up within the fabric to escape through the breathable structure. The result is a softer appearance to the interior, with curved edges to the plasterwork, and a design which retains the raw beauty of the original structure.
The plasterwork is not applied in the normal way. Ply shuttering is built up against the walls, with the plaster mix being placed in and tamped down, the formwork being removed only after the plaster has cured before the finishing coats are applied.
The solution offers great potential to insulate existing buildings whilst minimising the long-term potential damage to the existing fabric and has great potential for similar projects. Initially the contractor was reticent about the material, but having used it, has been singing its praises and taking other clients to see the newly refurbished building.