Design Case study

North Yorkshire Radical Retrofit

An extensive renovation of a 18th century Yorkshire stone barn. Natural materials have been prioritised throughout the design of this project. The pine king-post roof trusses have been left exposed in the existing building, and a new Douglas fir in-the-round column and glulam beam structure is used in the new glazed extension.

Client
Private Residential

Dates
May 2019 – present

Size

approx. 280 square meters

Budget
£3000/m²

Status
 
Building fabric completed, fixtures & finishes remaining

Collaborators 
Adam Carr Builders (Lead contractor)
Groves Architects Ltd (Principal Designer) Richard Bullows (Architect’s Model)

 

overview

This project is composed of two existing buildings; the original 18th century barn, and a 1990’s sandstone/limestone clad concrete block extension, which mimics the original. The layout of both buildings has been radically altered to produce a much more cohesive space, and each has been extended on their Southern facades. Each extension is angled towards the South-West to take in the sweeping views across the Yorkshire Dales, and to take best advantage of solar gain. They also bring increased light into the new open-plan living space. In both new & existing structures, hempcrete has been used to wrap the building in a super insulating skin of Yorkshire-grown hemp.

Studio Bio (UK Hempcrete’s in-house design studio) was engaged by the clients to detail the complete technical building envelope with bio-based materials, run moisture risk analysis and provide on-site hempcrete training.

The design

UK Hempcrete could not ask for a better clients with this project. They are committed to the use of hempcrete & other bio-based materials and see the added value this method of construction brings: brilliant thermal performance, improved indoor air quality, longevity, the natural beauty of the materials, and supporting the British bio-based material industry.

Projects like this allow us to engage with and train the kind of contractors we want to be involved with, thereby allowing us to expand the growing circle of natural builders in the UK. Our clients for this project are in fact repeat customers; having already renovated a townhouse in the nearby town of Settle. In their first project ‘Wonky House’ they internally insulated the thick stone walls with site cast hempcrete, and were immediate hemp converts! This initial smaller project gave them the confidence to use natural materials on this larger radical retrofit project.

The original building footprint was of two offset, adjoining rectangles with a small internal connection between them. Both existing buildings have been extended to the South with two chamfered glazed new-build sections, and a larger opening connects them together. The roof pitch of the original building has been reduced slightly in order to allow the roof line to continue over the new extensions, maintaining a single roof line. The sloping site has provided the opportunity to design-in a lower ground floor, providing ancillary rooms and storage areas. 

The larger original barn building houses the primary living space on the ground floor, and the family bedrooms on the first floor. The generous fully-glazed extension to the existing barn is the main feature of this project, and allows much needed natural light to penetrate into the previously dark barn. A simple mechanical ventilation system has been designed to gently feed hot air from the warmer glazed Southern area into the cooler Northern rear rooms, resulting in an equalised thermal environment that uses passive solar gain to heat the building in winter, and allows the thermal mass of the hempcrete & stone to adsorb the excess heat in the summer & therefore prevent summer overheating. 

The smaller 1990 building now serves the original barn as ancillary rooms on the lower & ground floors, and as a master bedroom suite on the first floor. The three floors are connected by a stylish cast concrete spiral staircase.

Both existing buildings have been internally insulated with 150mm of hempcrete cast against the existing rubble stone walls, with 1990 extension insulated with new-build 400mm thick cast hempcrete walls. All the hempcrete is finished with a generous layer of natural lime/hemp plaster. Natural wood and wool fibres have been used in the roof structure, with large Indian limestone slates used as the roof finish for all roofs. In the floors, a mixture of foamed recycled glass is used within the existing building footprint and expanded natural cork slabs are used over the beam & block extensions. 

The clients have chosen the building firm Adam Carr Builders, to lead their construction project. Adam Carr have been wonderfully receptive in learning how to use hempcrete & the other natural materials that we have specified. UK Hempcrete conducted an on-site training day prior to the hempcrete installation work stage, to give their tradesmen the skills and confidence to complete the hempcrete installation. Adam Carr have an eye for details and an enthusiasm for trying new methods of natural construction, both very valuable characteristics for any client’s contractor to possess.

The architectural model was created by Richard Bullows. More of his work can be seen at here.

energy performance

The heating demand has been reduced by the specification of a considerable layer of natural insulation throughout. Heat is supplied by several sources including passive solar gain, air source, solar PV and solar thermal.

Chris Hirst is having comparative EPCs (energy performance certificate) produced for the building, preliminary results are:

EPC before the project started
Energy rating F with score 21

EPC when the project is completed
Energy rating A with score 96

The Materials

Through our specialist material supply service, Natural Building Store, we supplied the following materials for this project:
 
Our expert team is ready to assist you and provide advice around the specification and use of these materials. The Natural Building Store is an online store specialising in cutting-edge bio-based and highly sustainable building products. Visit our website where you can browse our stock, build your own quotation and submit directly to our sales team who can advise and process the order for you.

Our Design Studio

Established in 2019, our in-house design studio, Studio Bio, developed out of an industry demand for designers with a specialist knowledge of bio-based construction and detailing.

Our director, Alex Sparrow, leads a growing team, designing buildings from a material-first perspective, to ensure that the implications of building with hempcrete are considered from the very first drawing. To find our more about our services, click the button below.

Contact

We have a range of packages for each design stage to suit your project. Call us on 01629 343143 or email design@ukhempcrete.com to discuss how we can get involved with your project! Alternatively, you can fill out the form below to receive more information about our design services: