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.
During the second phase of our renovation project in Haslemere, our clients took us out to visit the straw bale, roundwood timber-framed building used for accommodation for long term volunteers on this National Trust estate.
We built Speckled Wood entirely from timber grown on the National Trust’s Blackdown estate near Haslemere, Surrey. Named after a butterfly that frequents the local woods, the building is a roundwood frame of sweet chestnut, with larch wall plates and ridge pole. The chestnut shakes were constructed by volunteers on national trust working holidays. The building is used by long term volunteers/apprentices who then go on to work on other national trust land. By design, the residents should embody the essence of sustainability by living in speckled wood. Ben Law
With timber shingles and the undulating straw walls this building has a strong organic feel, fitting nicely into the surround landscape. Straw bale walls can be built to straight lines and sharp corners but the curves and undulations work well here, creating a warm and inviting atmosphere inside. The thick timber window ledges, lime plaster and hand-built roundwood staircase make this a great space to live when volunteering for National Trust.
The short trip provided a strengthening break to get some fresh air during an intense phase of construction as well as the chance to see work crafted by the hands of several of our colleagues and friends.
After a site visit on a 16th Century house in South Oxfordshire David used the opportunity to head up the road and catch up with Darren. Late last year Hawkland helped him with constructing the timber frame, installing the roof trusses and the compression of the straw bale walls.
Continuing on after battening down the hatches over winter he’s back on site and making good progress on the roof. The timber facias are in place and looking great. When David arrived he found him on the roof enjoying the spring sunshine carefully laying the slate tiles.
It’s really exciting to see the project progressing well and we’re really happy we where able to help him on his self-build project.
Recently Hawkland had the chance to visit the first Ecococon building in the UK. This is a single story dwelling built to Passivhaus standard using Ecococon’s straw panels. Additional STEICO fibreboard insulation was applied externally to the panels in order to meet the Passivhaus very low u-value requirements.
This is a great example of high quality design and detailing creating a building where modern technology and knowledge can interact harmoniously with natural materials. Timber, straw and clay are a powerful combination of natural, low environmentally-impacting materials that, when used in this way, provide a wall-system that helps to improve indoor air quality by regulating humidity, absorbing VOC’s and other gases, removing odours from the air and reducing mould growth.
In November Hawkland travelled over to Killgetty in Wales to work on the restoration of a large stone built farm house.
Our work was a small part of this large project that our client have taken on. Just over a year ago they brought this run down farm and have been working on it ever since. The main farm house is a beautiful stone building acting as the canvas to a collage of various eras and adaptations. The most unfortunate of which is instantly apparent in the above photo. The whole building, the walls around it and some of the attached out buildings has, at some point in it’s not so distant past, been cement rendered.
This over time has allowed the development of damp and mould growth within the building. The walls are solid stone with lime mortar and built directly onto the ground which allows for the movement of moisture up through the walls. This is okay when the walls are allowed to ‘breathe’ through the use of vapour permeable materials. However with the addition of the cement outside and gypsum inside these materials trap the moisture in the walls causing damp issues, giving rise to mold growth and the potential of reduced internal air quality.
The owners have already started to take off the cement from the outside and the gypsum plaster on the inside, allowing the walls to start drying out, although this can take a long time due to the thickness of the walls.
The ground substrate varied widely in each room. We went from digging through bed rock in the first room, lifting and removing a suspended timber floor, a solid concrete floor in the kitchen and layers of limecrete, concrete and various other additions in living room.
With two of us on site and working for six days we removed over 13m2 of soil and rubble and levelled the floors out ready for the foam glass gravel to be poured in up to 120mm deep and compacted down to 100mm. A large scale renovation, not for the faint hearted but in the end this will be a lovely farm house.
Whilst steadily growing in the industry, straw bale construction still makes up a relatively small part of the sector in the UK. Across many countries in Europe there is a lot of interesting and exciting activity underway, ranging from grassroots initiatives, new companies, creative and individuals and academic research. A lot of this knowledge and creativity is exchange through national and international bodies such as RFCP – Réseau Français de la Construction en Paille in France amongst several others, who are members of ESBA (European Straw Building Association).
The UK is one of the few countries that up until recently didn’t have a national body to represent the industry and to facilitate the exchange of ideas and knowledge for the pursuit of best practice and increased awareness of straw bale building.
SBUK (StrawBale Building United Kingdom) was set up by Jeffrey Hart and established with the collaboration of leading straw bale practitioners from across the UK. Still in the process of setting up and establishing itself as a fully fledge association SBUK is on it’s fourth meeting.
Hawkland managed to attend in the form of co-director David Copeland. The meetings are always a great time to catch up with friends and colleagues, whilst helping in any way we can to support this initiative.