UK Sweet chestnut and construction

The sweet or Spanish chestnut is not native to Britain and was probably first transported from the Mediterranean and Asia Minor by the Romans. Here it does best on the lighter soils in southern England. In Kent and Sussex, large areas are still actively coppiced on a 12 to 16 year rotation. The stems are cut back to the base or stool, several new shoots grow up and develop into straight poles, used for posts, fuel and cleft paling fences. In the recent past, the main market for chestnut coppice was for hop poles, as it is a very stable timber, so movement, distortion or splitting is reduced.

This species is well adapted to the acid soils of the High Weald, and grows vigorously on well drained slopes. A sustainable yield of 6 m3 per hectare per annum can be achieved - 100 tons of growth over 15 - 20 years. Chestnut grows very straight on good sites, and is valued for durable fencing materials, from paling to post and rail. Coppicing and cross-cutting to length takes place to meet market specifications, at any time from 12 yrs to 25 years. A new crop arises from the cut stumps, and as long as the shoots are protected from animals, this process is renewable for many cycles.

When allowed to grow to maturity, this tree yields a good quality timber resembling oak, but lighter, weaker and more easily worked. It is prone to suffer from a variety of structural weaknesses.

Chestnut has been the focus of research and development work for a number of years, to find modern uses for this local product. A finger-jointing technique to create long sweet chestnut cladding panels was developed by the Building Research Establishment (BRE) and structural data is available for its use in structural applications. Some of these innovative local products are displayed as part of the Woodland Enterprise Centre Building, located in Sussex.

Today sweet chestnut cladding is often available single piece random lengths (1.8 – 3.5mt+) depending on the cycle or now as a result of the finger-jointing technique it is available in standard 4.0mt finger jointed lengths. The jointed technique allows shorter lengths of sweet chestnut to be used reducing sawmill waste. Sweet chestnut It durable and stable partly because of the high tannin content, which will leach from the boards in the first few month of installation, and can cause streaks and stains. Because of the tannin, austenitic stainless steel fixings should be used to prevent corrosion.

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