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Factors to consider
Timber is an integral material to many of our products, especially seating. It has a natural beauty and warmth and will change its appearance over time as it is subjected to the elements in outdoor situations. Set out below are some of the factors to be considered in determining the most appropriate timber species for your project: 

  • Durability: The durability of timber is based on the results of placing testing hardwood samples into the ground, fully exposed to the elements, with the number of years before decay becomes obvious determining the durability of the natural (untreated) timber into one of five classifications: 

Cl. 1. Very Durable: 25+ years; Cl. 2. Durable: 15-25 years; Cl. 3. Moderately Durable: 10-15 years; Cl. 4. Non-Durable: 5-10 years; Cl. 5. Perishable: 0-5 years. 

The hardwood of species with a rating of Durable or Very Durable can be successfully used in exterior situations without the support of preservative treatments. Further information on durability classification and timber generally can be found on the Timber Trades Federation website at: http://www.ttf.co.uk

  • Stability: Some timbers are more liable to twist and distort than others, due to the varying grain structure and how it responds to the elements, and in our furniture we prefer to use the more stable species. Regardless of species, all timber will ‘move’ to some extent as its moisture content changes in varying climates, resulting is fissures or cracks during hot, dry conditions, but which will tend to close up in periods of cold, wet weather. 
  • Aesthetic appearance: There is a huge variety of colour and grain characteristics across different timber species, preferences on which are very much subjective. Photos of timber products and component parts shown on our website and in our e-brochures are generally new products with freshly machined timbers (<3 months old), before any significant weathering has occurred that will cause the original timber colouration to fade.
  • Density: The density of the timber is important in two respects – firstly to perform its structural function (with an appropriate visual mass), and secondly to resist marking in general wear and tear. In simple terms, the denser the material the lighter the section can be and the more resistant it is surface marking. Generally speaking the more dense the species, the higher its cost. 
  • Sustainability: It is important to us that we provide options for specifying and using timber  from sustainable sources, full details of which are provided under the ‘Furnitubes' Timber Policy’ heading below. 
  • Supplementary finishes & maintenance: The natural colouration of new machined timber will fade as it is exposed to UV light, fading to a weathered patina that some people prefer in a landscape setting over the original colouration. Many proprietary timber finishes are available, which bring varying degrees of maintenance implications, which are discussed in further detail.
  • Costs: Converting timber from a tree to a useable machined section is a labour intensive process, and with tropical hardwoods especially, involves considerable transportation – all of which adds to the cost of the raw material. With our standard product range our approach is generally to use timber sparingly, in sectional sizes that are appropriate to the performance requirement, and often supported by structural steelwork. Our design department is happy to offer advice on the appropriate material sizes that will minimise the cost of timber product and components. 

Preferred timber species
Listed below are the primary timber species that we generally use, a brief summary of their characteristics and their typical product applications. 

  • Iroko: A West African species that is rich in natural oils with a ‘Very Durable’ classification, which is also relatively stable, readily available and is cost effective. Iroko is the timber that we use on the vast majority of our timber surfaced seating products, most often supplied in a smooth planed finish that will typically fade to silver-grey within 12 months. If supplementary treatments are required to retain the original colouration for longer, the natural oils must be either allowed to dissipate through weathering over a period of around 3 months in an external environment before application, or be cleansed if treatments are applied at the outset (applying a treatment directly to freshly machined timber will tend to result in it sitting on the surface and not penetrating into the grain).  
  • Teak: Teak is a deciduous hardwood of ‘Very Durable’ classification, sourced from South East Asia. Like iroko, it has a naturally high oil content making it steadfast, as well as resistant to rotting. As with all natural timber, teak will fade to a silver grey colour over time if exposed to weathering and sunlight in particular. Treating with proprietary teak oil will darken the grain and add a glossy finish of teak, but is essentially a cosmetic treatment only.
  • Oak: European Oak is a species that it is often requested, but less often supplied, for a number of reasons. Firstly, it is classified as ‘Durable’ (iroko is ‘Very Durable’), secondly it is prone to unattractive black surface marking from unavoidable reactions with metal saw or planing machinery, and lastly because of its tendency to leach natural tannins (oils), which can be problematic on seating in particular and can also stain surrounding hard surfaces. Oak is also more prone (than iroko) to movement as it weathers, causing sometimes significant fissures as it dries out. For the above reasons oak is generally used more for ‘rustic’ products such as bollards and posts than it is for seating.
  • Modified softwood: Most softwoods in their natural state are Durable at best. Modification of softwoods through thermal and / or chemical treatments can provide a dense, dimensionally stable, highly durable material with an aesthetic and performance comparable with tropical hardwoods, and also protects against decay, fungi, insects and other microorganisms. The natural colouration after modification is generally a mid to deep brown, which will acquire a silver-grey patina after around 12 months exposure to the elements, much the same as with any other timber. Although there is no need to coat the timber from a durability point of view, modified softwood is receptive to coatings that will help retain and replenish natural oils and resins lost through weathering, improve water resistance and maintain a richer colouration over a longer period. As with treatment of iroko, we recommend penetrating coatings rather than film-forming treatments that are vulnerable to breakdown and unsightly flaking. Modified softwoods are generally designed for decking and cladding applications, meaning they are only available in relatively small sectional sizes, which can be used for seating purposes, although it can be laminated to form larger sizes. 
  • Wood preservative impregnated (pressure-treated) softwood: Softwood species such as Spruce or Whitewood can achieve Moderate Durability classification through impregnation with a wood preservative treatment, which protects against wood-destroying organisms and improves their lifespan in the external environment. Unlike the modification process described above though, this does not significant change the density of the timber, so these softwoods are best used on products such as bollards and posts rather than seating, which are more vulnerable to marking. It is advisable that any sections cut out of the original supplied material are further treated with preservative, particularly if the product is being installed in the ground.

Furnitubes' Timber Policy
Forest Conservation and Replantation
All hardwoods used by Furnitubes are supplied only from countries where governments operate strict controls on the size of trees that can be felled and where a forest conservation policy and replantation programmes are in operation. The countries of origin for Teak and Balau are Malaysia and South East Asia with Iroko and Ekki from the West Coast of Africa, predominantly Ghana and Cameroon. From the hundreds of trees available, the timber logger rarely takes as many as thirty trees and then only those with the dimensions as ruled by the government. After the trees have fallen in a particular area the forest is left alone for a minimum period of 25 years. The main problem is undoubtedly the over population in those parts of the world where the huge natural forest and vegetation areas are being cleared by burning, so that the land is then available for agriculture and building. This action not only destroys the trees that could have been put to better use, but releases carbon dioxide adding to the 'greenhouse' effect.

FSC Certified Timbers
Furnitubes is not directly registered with the Forestry Steward Council (FSC). Where certified timber is specified or offered the material will be purchased as such from our timber merchants, who will be the end named party in the chain of custody certification, which will be supplied if requested. The terminology that we may use for such material is ‘timber from a well-managed source’.

Address: 3rd Floor, Meridian House, Royal Hill, Greenwich, London SE10 8RD

Telephone: +44 (0)20 8378 3200

Email: sales@furnitubes.com

© Copyright Furnitubes International Ltd, 2010-2016

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