Coppiced sweet chestnut in UK construction – challenges and opportunities for design development of hardwood building products

Figures & data

Table 1. Focus group participants.

Participant	Supply chain representation/Industry background	Focus group
1	Timber Architecture Journalist/Writer	1
2	Wood Furniture Maker	1
3	Land Owner with Sawmill	1 + 2
4	Sweet Chestnut Fencing Manufacturer + Forest Owner	1
5	Forester	1
6	Forestry Consultant	1 + 2
7	Structural Engineer	1
8	Landscape Management Consultant	1
9	Sweet Chestnut Fencing Contractor	1
10	Timber Building Design Consultant	1
11	Timber Framer & Advanced Timber Structures Specialist	1
12	Academic - Timber Architecture	1 + 2
13	Timber Industry Campaign Director	2
14	Academic - Architectural Technologist	2
15	Architect - Timber Specialism	1 + 2
16	Academic - Wood Science & Technology	2
17	Wood Consultant + Wood Journal Editor	2
18	Timber Framer/Carpenter	1 + 2

Table 2. Sourcing focus group – key themes.

Theme	Description
1) Sorting:	Better utilising coppice workers skills to accurately batch qualities of coppiced poles so that high quality straight material can be identified for use in the manufacture of construction products.
2) Mixed aged trees:	Design briefs for building products must reflect the mixed age of coppiced trees that currently grow in coppiced woodlands in England.
3) Capacity to meet demand:	There is sufficient supply of coppiced timber to meet new construction demand for local architecture in England.

Table 3. Technical challenges focus group – key themes.

Theme	Description
1) Alignment with local processing tools	The use of simple and widely available processing tools such as mobile sawmills is necessary to align with the reality of the local UK timber processing network.
2) Use of cleaving	Inclusion of cleaving alongside sawing as a process of roundwood conversion is needed to take advantage of the high timber yield of splitting.
3) Use of unseasoned timber	Unseasoned coppiced roundwood should be used for ease of cleaving and to embrace the dimensional stability of green sweet chestnut compared to other hardwood species such as oak. There is also limited access to kiln-drying facilities in southern England.
4) Public communication/stakeholder engagement	Raise awareness of the benefits of coppice management of sweet chestnut and potential uses in construction.

Figure 1. Radial cutting of 300 mm diameter coppiced sweet chestnut log.

Figure 2. Five building product prototypes and corresponding 3D models and structural simulation.

Figure 3. XR beams used in a prefabricated flooring and a-frame system.