Project : Coppice Oratory
Place : King’s Wood, Challock, Kent, England (Latitude 51.226586, Longitude 0.93740194)
Construction : 2023

Client : Kent Downs National Landscape (aspiring UNESCO Cross Channel Geopark)
Structural Engineer : Format Engineers (James Solly and Matt Church)
Build Team : Matthijs la Roi, Simone Tchonova, Coen la Roi and Miguel Amorim
Photographer : Valerie Bennett

The Coppice Oratory is a place of rest along an ancient pilgrim’s way. It marks the first sighting of Canterbury Cathedral seven and a half miles in the distance on the historical pilgrimage route from Winchester to Canterbury. The structure is made of hundreds of sweet chestnut coppiced poles brought together from the surrounding woods.

The site is nestled at the edge of King’s Wood near the town of Chilham in Kent and is adjacent to a part of England’s protected public footpath network and the 123 mile North Downs Way National Trail. Chaucer’s Canterbury Tales’ pilgrims followed the same historical route on their pilgrimage. From the position of latitude 51.226586, longitude 0.93740194 a view corridor is preserved across the Kentish Countryside. The central axis of the Coppice Oratory is in alignment with the view to Canterbury Cathedral towards the North East. 

A seat spanning the entire length of 5000 mm is integrated into the structure at a perpendicular axis to the central view corridor. There are two openings that serve as entrances to the interior space, one at the south and the other at the east which also aligns with the view of the Cathedral. The widths of these wedge openings are 1220 mm at their widest point, a dimension determined by the needs for a terrain mobility scooter to enter comfortably. The width of the interior space is determined by creating adequate space for a turning radius of 1500 mm. Accessibility drove the setting out dimensions. The third opening is the oculus, exposing the interior to the sky. 

Coppiced Sweet Chestnut trees make up a substantial portion of the 588ha King’s Wood woodland and of the Kentish landscape. This species of chestnut was brought by the Romans for their edible quality. Coppicing the Sweet Chestnuts at the base is a practice particularly preserved in Kent. The cutting of a tree occurs every 10-20 years. At this time the diameter of the timber is adequate to be used for fencing, furniture and hop poles for vines. Forestry England preserves this practice in King’s Wood year round based on a cycle of coppicing different areas each year. This human management of the forest promotes a larger biodiversity as different areas of the forest floor are exposed to varying sunlight levels. 
Coppiced timber is a material which does not end the life of a tree but keeps its root structure in place and healthy to continue growth, this differs from completely felling a tree. The hard wood produced is durable and can last upwards of 20 years. This timber is not regularly used in buildings as it is irregular in its form due to natural formation.

The logger from King’s Wood typically delivers logs in bulk orders of as-is lengths and diameters and are predominantly used as fence posts and hop poles in agriculture and forestry. Requesting to cut each log to a custom size is uncommon and comes at a high cost thus the material was ordered in a series of as-is lengths and diameters. After delivery from the surrounding woods, the logs were sorted based on their lengths, diameters and degree of irregularity. The log lengths range from 1800 mm to 4750 mm and in diameter from 90 mm to 150 mm. There are two types of cuts used on the logs, the first is a traditional cut perpendicular to the length - these logs make up the interior space. The second type of cut is an 8 degree angled cut making up the long elevations as patched surfaces of angled cuts. 11 degree angled cuts make up the entrance wedge openings. All angled cuts were made with a chainsaw and traditional cuts with a hand or mitre saw. Each cut of a log exposes the inner grain.
All logs are connected in the same method, 15 mm oak dowels globally and steel rods locally placed at key structural load points. The decision to use dowel connections resulted in a structural challenge. There is currently no codified design guidance for using timber dowelled connections in the United Kingdom. With the use of computational modelling and physical testing, the structural principles were established by the Structural engineers. Due to the differences in material mass and positions of the logs in relation to the primary structure, varying densities of dowel connections were required based on structural loads.
A system of construction was established to utilise the irregularity in the raw materials as opposed to controlling the timber through an industrial process of milling and standardisation. This included the density requirement of dowels at varying locations, the minimum pole diameter required, and the maximum gap distances. Poles were connected with dowels in the following procedure: A pole was lifted vertically and placed next to a fixed pole on top of a vertically configurable footing and fastened with straps. With a high power drill and a 400 mm auger bit a hole was drilled through the centre line of two poles to be connected. A dowel would then be hammered through both logs. Each log would be connected to a minimum of two other logs with variable directions of the joints. This process continued until the 5000 mm x 2650 mm x 4050 mm build was completed.
The placement of logs was a collaborative effort between builders with a set of rules and boundaries rather than a complete set of drawings. Each builder made daily decisions on choice of log, curvature tolerances, log orientation and dowel placement.
Untreated raw bark has been left to remain on the logs, in various locations there are markings from the loggers and from the construction process visible within the bark. In time the bark will loosen and fall off.