Join us along with Green Register members Dovetail for a site visit to a Timber Frame new build project in Bristol, BS6. Address will be confirmed on booking.

This central Bristol sustainable self-build was initially conceived by Ben Hamilton Baillie, an urban designer who helped complete the UK’s National Cycle Network, and transport initiatives such as ‘Safe Routes to Schools’ and home zones. Since his passing in 2019, Ben’s wife Jennifer has worked tirelessly to continue the vision and bring their home to life.

Perched on the top of the hill, this unique plot is believed to be the site of a 17th century summer house overlooking the old town of Bristol. The site passed to the ownership of the Montague Tavern opposite, which was destroyed during WWII. According to a 1900 Bristol Guide it was 'once famous all the whole gastronomic world over for its turtle soup and civic feasts.’

Several items of archeological interest were uncovered during the excavations, including a large cellar. This complicated the foundations and led engineers Structural Solutions to choose a reinforced in-situ concrete ‘raft’ solution, to bridge the cellar and create a solid base for the building.

Architects Marshall and Kendon (Clifton Lido, Water Lilies eco community) took the drawings through planning, including the challenges of building in a conservation area, to design a highly energy efficient family home, taking an inventive approach to materials and techniques. The builder, Dovetail, worked collaboratively with Marshall and Kendon to develop the construction details and achieve some unusual sustainable details.

Structure:

Dovetail used their timber frame experience to deliver a light touch ‘stick built’ frame, reducing disruption to the neighbours from heavy plant, and reducing factory running and transportation costs, both environmental and monetary. Unusual for an inner city site, the ground floor is a suspended timber, reducing the amount of concrete used and reducing the carbon footprint of the building.

Thermal envelope:

The building features the Holy Grail in sustainable building - an almost unbroken thermal envelope. The insulation is placed fully on the outside of the walls and roof, which reduces cold bridging to almost zero, and neatly side-steps issues at floor junctions. Ground floor insulation is laid over the timber floor structure, with underfloor heating and timber floor finishes applied directly over the insulation, negating the need for concrete screeds and reducing concrete still further.

Airtightness:

The air barrier is also placed externally on the frame, sandwiched between the studs and the insulation. This avoids awkward junctions and floors and roofs, and service penetrations, and keeps it away from damage during construction. Ventilation is achieved mechanically with heat recovery, which is powered by solar panels on the roof.

Insulation blocks:

Reducing cold-bridging is typically difficult to detail at the ground floor and wall junction. Marshall and Kendon have achieved this with an innovative use of Marmox Thermoblock, a product designed for use with masonry. This is the first time this product has been approved for use within a timber frame.

About the trainer:

Dovetail is a Bristol based builder and main contractor, with a reputation for high quality sustainable homes and spaces in and around Bristol. Their new build projects include a green oak and Hempcrete monastery, low carbon timber frame homes, and cutting-edge sustainable offices. With 25 years in the industry, Dovetail director’s Will Hallett will be guiding the visitors on site and sharing his experience of timber frame and sustainable building practice. Accompanying him will be project managers Nigel Shelbourne and Rosie King, alongside site manager Jean Goubert.

Visitors will be able to see the timber frame structure, Marmox insulation block & air barrier detailing. Some windows and insulation may have been fitted. They look forward to welcoming you and showing you around this interesting site.