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Timber Cladding – Specification and Choices

Timber Cladding – Specification and Choices

Timber Cladding – Specification and Choices

External Siberian Larch Preweathered Old Look from Timber Focus

Timber Cladding – Specification and Choices

Product specification guide: advances in treatment and preservation are increasing timber’s sustainability
Increasingly timber is being specified as a rainscreen cladding system for external walls. It is commonly thought of as a sustainable option due to being renewable, recyclable, biodegradable and having minimal embodied energy. This can, however, sometimes be counteracted by the treatments needed to protect it from excessive weathering.
Often when used outside, timber can deteriorate quickly. The main cause of this is usually moisture. As the moisture content of timber used externally for cladding often exceeds 20 per cent, it may need to be treated with a preservative; this can outweigh the sustainability benefits of the material. BS 8417, covering the preservation of timbers, draws on a number of European standards to facilitate the selection of timbers and the type of preservative treatment necessary for lifespans of 60, 30 or 15 years in different hazard classes.
Timbers that do not require preservative treatment include: Western red cedar, European larch, European oak and Douglas fir. These woods are naturally resistant to insects, moisture and rot. Spruce, fir and pine have to be treated, which involves impregnating them with chemicals such as boron. Spruce has been used extensively for cladding applications especially in Scandinavia as it takes external coatings very well and you will see it as black or white featheredge cladding in the UK.

Black Cladding
Black Painted Exterior Timber Cladding

A preservation method that is becoming increasingly popular is one that involves heating the wood. Originating in Finland, the process thermally modifies the properties of the timber improving its lifespan, strength, durability and stability.
The design of a building can make a large difference to the durability and lifespan of timber cladding. The cladding should be protected from exposure to high levels of moisture but designed with the presumption that water will penetrate it. When using other natural materials, the ‘good hat and boots principles’ is often cited. This should be the same for timber cladding: it should be raised away from the ground by a minimum of 250mm to avoid excessive damage at the splash line at ground level, and a good roof overhang should be provided to minimize the impact of weathering.

Fire Retardant Treatment is one area that is very critical especially if required by building control, The supplier of the fire retardant timber cladding to Euro Class B MUST be able to supply a third party audit certificate fire retardant certificate through an Independent Notified Body from the NANDO organization. EN13501-1. In the UK only, a few companies can bring or sell to market fire retardant timber cladding and one of them is Timber Focus Ltd through its partner Puidukoda OU. You will unfortunately see many organizations including big organizations trading or selling timber breaking the law in terms of fire regulations and supplying fire retardant timber cladding issuing fake documents due to lack of knowledge. We keep fire retardant timber cladding in stock or you can buy online.

With the introduction of the government’s Green Deal scheme there is likely to be an increase in thermal upgrades, with solid-wall properties being insulated externally and additional rainscreen cladding added. This could see a rise in the use of timber cladding.

ThermoWood

Thermowood Cladding Timber Focus
Thermowood Cladding Timber Focus

ThermoWood
ThermoWood is heat treated, making it more stable than untreated wood. Thermal modification can be applied to several timber species either to make them more stable or durable or both e.g Thermowood D or Thermowood S. Species that are common include Ayous, Ash, Tulipwood, Whitewood (spruce), Pine (redwood)
Thermowood Redwood Pine softwood is the most common type of thermowood available on the market for decking and cladding applications. The heat treatment changes the chemical make-up of the timber, so it is less able to absorb moisture. This restriction of moisture movement limits any potential for swelling, shrinkage or distortion.

Type of cladding Horizontal and vertical
Profiles available Tongue and groove shiplap, channel cladding, tapered cladding, battening and cornering
Wood species Scandinavian Redwood
Treatment Heat treated at 200°C
Life expectancy 30 years
Country of origin Finland
Maintenance Annual inspection recommended
Certification PEFC certified

Accoya

Accoya by Accys Technologies
Accoya wood is made from softwood but has the qualities of hardwood, produced via a process called acetylation. Acetylation transforms the free hydroxyls in the wood into acetyl groups, reducing the wood’s ability to absorb water, making it more dimensionally stable and more durable. We supply Accoya profiled and prepainted in various tones from our factory in Estonia.
Manufacturer Accys Technologies
Type of cladding Horizontal and vertical
Wood species Softwood, for example Radiata pine
Treatment Acetylation
Life expectancy 50 years
Maintenance Low frequency due to increased dimensional stability as coatings do not stretch and shrink
Certification FSC, PEFC certified and cradle-tocradle gold standard
Recyclability Can be reused or used as a biofuel to produce heat and power
www.accoya.com
Imported External Cladding System

Imported External Cladding Panel System by BCL Timber Products
This external timber cladding panel system allows the cladding to be prefabricated, which means large areas can be constructed in a fraction of the time of traditional site-fix methods. All BCL cladding panel systems have concealed fixings, creating a smooth and continuous finish.
Manufacturer BCL Timber Products
Type of cladding Horizontal and vertical
Profiles available Horizontal: open harfield, shiplap, feather edge. Board on board
Wood species Western red cedar, Siberian larch, European oak, South American hardwoods
Treatment Protim or similar
Finishes Translucent or clear lacquer, paint
Maintenance Lacquer: 5-7-year repaint cycle Paint: 15-year warranty
Certification FSC or PEFC certified
www.bcltimberprojects.co.uk

Homegrown External Cladding System

Homegrown External Cladding Panel System by BCL Timber Products
These prefabricated cladding panels minimise the amount of work that must be done on site when installing the cladding. They are produced using home-grown timber species, thereby reducing their carbon footprint and environmental impact.
Manufacturer BCL Timber Products
Type of cladding Horizontal and vertical
Profiles available Horizontal: open harfield, shiplap, feather edge. Board on board
Wood species Sweet chestnut, cedar, larch
Treatment Protim or similar
Country of origin UK
Finishes Translucent or clear lacquer, paint
Maintenance Lacquer: 5-7-year repaint cycle. Paint: 10 year warranty
Certification FSC or PEFC certified
www.bcltimberprojects.co.uk

Siberian Larch Cladding

Siberian Larch Cladding  supplied by Timber Focus data sheet
Siberian larch is a sustainable old-growth timber, which is durable, dimensionally stable and long lasting. It is naturally resistant to decay, meaning it has a long lifespan and requires minimal chemical treatments.
Manufacturer Timber Focus products are available to buy from the Timber Focus online shop
Type of cladding Horizontal or vertical
Profiles available Rabbeted bevel
Treatment
Life expectancy 25 years
Country of manufacture Russia
Finishes Factory applied clear stain or custom solid paint colour
Www.timberfocus.com

Certigrade Western Red Cedar Shingles

Certigrade Western Red Cedar Shingles
These cedar shingles are produced from waste from British Columbia’s main logging and sawmilling industry, providing a sustainable and environmentally friendly product. The natural effects of aging and weathering will give the product a silvery grey colour in time.
Manufacturer Timber Focus
Type of cladding Tiled cladding and roofing
Length of shingle 405mm
Width of shingle 75mm-365mm
Butt thickness 10mm
Wood species Western red cedar
Treatment Natural oils act as preservatives against decay and insect attack
Life expectancy 50 years
Country of origin Canada
Certification FSC certified

Western Red Cedar Shingles

Western Red Cedar Shingles
Shingles can be laid in straight lines, giving a clean regular appearance to the roof or wall; alternatively, random butts can be used to give a much more irregular aspect. The shingles are light, reducing both the carbon footprint of transportation and the structure required to support them. Cedar shingles are available in a number of quality timber grades the top grade is blue label 5x followed by red label and the lower grades are the black label grade.

Type of cladding Tiled cladding and roofing
Length of shingle 400mm, 450mm, 600mm
Width of shingle Random
Wood species Western red cedar
Treatment Untreated or treated with Osmose Naturewood preservative treatment
Life expectancy 40-60 years
Country of origin Canada
Certification FSC and PEFC

Western Red Cedar Shakes

Western Red Cedar Shakes
Shakes differ from shingles in that they have a split, rather than a sawn, face and have a low-carbon footprint. When used, they create an aesthetic akin to that of traditional log cabins, and have a low carbon footprint.

Type of cladding Tiled cladding and roofing
Size of shake 600mm x 19mm
Width of shake Random
Wood species Western red cedar
Treatment Untreated or treated with Osmose Naturewood preservative treatment
Life expectancy 40-60 years
Country of origin Canada
Certification FSC and PEFC certified

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