Hawkland have been delivering an internal wall insulation of a late Victorian semi-detached house in Haslemere. This has been in collaboration with Natural Building Technolgies who provided training for David during the early stages of the project.
Pre-1919 buildings, classed as traditional buildings by Historic England, are built with a very different approach to moisture movement through its building fabric.
“This category includes nearly all buildings constructed prior to 1919, as well as a significant proportion of those built before 1945. It is essential that adaptations made to improve the energy ef ciency of these structures should take into account the traditional technology and characteristic behaviour of the building fabric, otherwise very real damage can be caused. Well-meaning attempts to keep moisture out of these buildings using modern methods tend to have the unfortunate effect of preventing the vital evaporation, and thus causing or accelerating moisture-related decay to the fabric.” Energy, efficiency and historic buildings – Historic England
So the first step here was to take the walls right back to the brick. This is the quickest way of removing the layers of paint that have built up over the years. These vinyl paints inhibit the movement of moisture and can lead to damp issues and mould.
The walls are then ‘dubbed out’ with Baumit RK38 to level to uneven walls, minimising air gaps behind the fibreboard insulation. Once the plaster is dry the boards are cut and fitted to the walls with Baumit RK70 applied to the back of the board and fixed to the wall using special masonry fittings that are provided by NBT. We used Pavaflex flexible insulation to insulate in-between the joists to maximise the possibility of creating a continuous thermal envelope.