Nick Taylor, managing director at Silva Timber discusses what to consider when specifying timber products including species, sustainability and finishing.
Wood is natures most versatile and unique material. The fact that it has been used in building for hundreds, even thousands of years is perhaps not surprising when you consider some of its impressive attributes. Wood is strong, durable, long lasting, restorable, recyclable, renewable and of course, attractive. The fact that no two pieces of wood are the same only adds to its appeal. With it’s myriad of grain patterns, characteristics and colour tones, wood is a beautiful material that cannot be replicated by man-made products. If installed and finished correctly, wood can last externally for decades without being replaced. It has one of the most efficient life cost cycles in the construction industry. Being 100 per cent natural and highly versatile, wood is guaranteed to provide a stunning finish to any commercial or residential project.
What species should I use?
There are many different wood species on the market, so it’s worth considering firstly what the timber will be used for; decking, cladding, fencing etc, then how you want your project to look and feel. There are some beautiful wood species out there for a range of uses, including:
Western Red Cedar: Most commonly used for cladding, decking, fencing and roofing. A beautiful softwood which is resistant to both insects and rot and is extremely lightweight and durable. It is ideally suited to exterior and interior use and can be used for a range of applications. Over time it ages to a stunning silvery grey but also takes wood stain exceptionally well, making it easy to achieve your desired look.
Siberian Larch: Another naturally durable softwood most commonly used for cladding purposes due to its excellent durability, high density and lifespan not to mention its aesthetic appeal.
If using a tropical hardwood it’s worth considering a lesser-known species too. High commercial demand for certain wood species has put pressure on available stocks. In some cases to preserve biodiversity, countries around the world have banned the trade of certain species, while other species are difficult to source or prohibitively expensive. There are hundreds of species in the world that offer similar aesthetic appeal and performance to traditionally harvested species. The cost of these species is relatively low because they are under used and abundant.
Mandioqueira is a perfect example of a lesser known timber species that is ideal for exterior applications. This naturally decay resistant tropical hardwood species offers excellent performance being dimensionally stable and highly durable. It’s very attractive too with unique colours coming through, including pinkish brown to red brown, sometimes olive brown tones. Lesser-known tropical species offer three distinct advantages:
• They can often substitute better-known species in terms of performance and aesthetics whilst being more cost effective.
• The many different species of wood available with rich, truly exotic colours and textures provide new design opportunities for your project.
• The use of lesser-known timbers can alleviate pressure on well-known timber species and increase the economic viability of sustainable forest management.
How do I make sure my timber is sustainably sourced?
Using lesser-known species is also a great way to support the environment, by utilising a range of timbers we can ensure that species are not exhausted and put under threat of extinction. The CITES list (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a great resource and offers a way to check if a species is endangered before you complete your purchase.
There are several things to look out for when purchasing timber. Awareness of FSC (Forest Stewardship Council) and PEFC (Programme for the Endorsement of Forest Certification) has risen over the last decade and most timber suppliers will be able to offer certified timber.
How do I protect the timber?
Protecting timber with a suitable finish is an important but often overlooked step.
Traditional exterior finishes form a film over the wood to seal out moisture; however this type of finish is prone to failure if the film fails or becomes damaged and allows water to penetrate. Once water gets behind the film it can cause the finish to crack, peel and flake and the only remedy is to strip off the failed finish and start again – an extremely time consuming and costly process.
Many traditional solvent-based finishes also contain VOC’s (Volatile Organic Compounds), which continually emit chemicals that can have long-term health effects for years after application. To reduce the VOC levels in their products some manufacturers have switched to water based finishes.
You can have the best of oil based and water based finishes with a water-bourne alkyd based finish; which contains no VOC’s and is environmentally friendly. It works by using water to carry modified natural oils and resins deep into the wood’s cell structure. The water then evaporates allowing the finish to bond directly with the wood substrate enabling the wood to breath whilst forming a tough, durable barrier that won’t crack, peel or blister. If the timber is well maintained it will grow old gracefully and will not discolour.
When deciding on a stain it’s important to understand the characteristics of the timber species it is being applied to. The effect of the stain will vary depending on texture, grain, colour and porosity so always check the colour on samples of the timber being used. There are various staining options; natural and translucent tones, which let the beauty of the wood shine through or saturated and ultra saturated tones that provide a more solid colour appearance to the timber.
The key to an excellent finish is preparation; always ensure that the timber is clean and dry and begin by sanding the surface with an orbital sander using 60 grit sandpaper. Sanding the timber thoroughly removes mill glaze and creates an even surface and a slight texture that allows the stain/finish to penetrate the wood, providing an even, consistent and long-lasting finish. Studies have proven that sanding can extend the life of a finish by up to 3 times compared to an unsanded surface.