Timber – Design Tips

The pros and cons of timber

Timber is a traditional and well-loved material which is aesthetically pleasing too. Indeed, whether it is used in exposed or concealed applications, timber has many advantages. It has low-embodied energy, great thermal insulation unlike steel or masonry, is non-toxic unlike plastic, does not disturb natural electro-magnetic fields like metal, stores carbon and is truly renewable, recyclable and bio-degradable unlike most other materials. So timber is a great choice, which doesn’t mean that it should be used without discernment however.

Precisely because it is natural and biodegradable, timber is prone to degradation over time and may need some protection against termites, borers, mould and rot – something we tend to address with chemicals, compromising the non-toxic nature of the material and driving the need for more chemical production. The other significant parameter of course is that of conservation: timbers haven’t been harvested sustainably enough in the past, leaving us with dwindling reserves and disappearing natural habitats.

The case of the disappearing hardwoods

I once attended a lecture by a Yale University alumni who was talking about long-term financial planning. As an analogy, he related the story of how the governing body of Yale, when erecting a particularly large hall on campus two centuries ago, acquired a piece of land to establish an oak plantation that could be used when the great roof beams would need replacing, maybe a century or more down the track. A truly inspiring story that talks of foresight and great wisdom. Short term thinking and greed are certainly the enemies of sustainable forestry. Where it takes twenty years to grow a softwood forest to maturity, it takes fourty to fifty years for our native hardwoods. Few investors have been interested in planting hardwoods where the supply in Australia was thought plentiful and the financial returns would probably not come in the investors’ own lifetime. There are commercial hardwood plantations nowadays, but most of them only have young trees and produce small quantities resulting from thinnings. The bulk of the hardwood supply come from managed native forests, with the sustainability of their management usually a function of the person you talk to. It is to be noted that the majority of hardwood forest logging in Australia still caters to the paper industry – truly not the best use of our very strong and durable native timber. 

The case of plantation softwoods

Plantation softwoods such are Radiata Pine are used extensively in construction nowadays, which somewhat relieves the pressure from native hardwood forests. Whereas older homes in the Australian suburbs typically feature hardwood framing for floor and roof, hardwood floorboards, windows, architraves and skirting boards, and, unless they are solid brick, hardwood wall frames as well, this extensive use of hardwood is a thing of the past. Many homes now have a concrete floor, plantation pine wall frames and roof trusses, particle board joinery and MDF skirting boards and architraves. The main issue with softwood plantations is that they are monocultures and therefore do not promote biodiversity. This aside, they are a quick-growing source of timber for all applications that are protected from the elements. These include concealed structural applications such as wall frames and roof trusses as well as interior applications such as shelving, architraves and skirting boards. Pine, either in long boards or finger jointed, makes for a durable and non-toxic alternative to melamine particleboard and MDF in the latter cases.

Chemically-treated softwoods

The situation is a bit trickier for outdoor timber applications because softwoods, unlike many hardwoods, only have a lifespan of two or three years when exposed to constant moisture and/or rain. As naturally durable hardwoods are much pricier, our modern response is to chemically treat softwoods – read: introduce some sort of poison onto or into them to deter any form of life from decaying them. Commercially available pine fascias, sleepers, deck posts, rafters or joists will be either surface-coated or pressure-treated with chemicals to extend their lifespan rather indefinitely. The alternative is to use either sustainable hardwoods or other materials altogether – more on these alternatives later. Although used externally as well, plantation pine weatherboards and windows are considered less exposed and are generally not chemically treated. They will need painting however but will provide decades of good service provided adequate maintenance of the paint layer is performed. Another chemical treatment available on the market these days aims at protecting pine wall and roof frames against termite infestation. Rather than intensify the chemical load in the home, I find it preferable to use mechanical barriers – mesh or graded stone –at the base of the building, thereby preventing termite entry and maintaining the sound nature of timber as a healthy building product.   

Sustainable sources of hardwood  

Although it is easier these days to not use any new hardwood at all in home construction, it is still commonly used for  windows, floor framing (if a concrete slab is not in order), floorboards, deck framing and decking. If you are using new hardwood for these or new timber generally, specify as a priority the ones carrying the Forest Stewardship Council (FSC) or Australian Forestry Standard (AFS) certification – both have a website you can browse. Although some groups lobbying for forest conservation have reservations about them, they are the only forestry standards we have in Australia and products carrying their certification label are therefore deemed to have better environmental credentials than those that don’t. Information about the sustainability of hardwoods and hardwood products can also be obtained from Greenpeace Australia Pacific which has an interactive online Good Wood Guide, a more optimistic version of  the one published by Friends of the Earth a decade ago – also available online as pdf. As a rule, they both agree to generally avoid timbers from Africa, South America and South-East Asia (well-known species of these are Meranti, Merbau or Kwila), as most of them are logged from rainforests – it is indeed difficult enough to control what is happening on our soil, let alone monitor the logging practices of countries less wealthy than ours…

Alternatives to new hardwood

It is possible nowadays to use no new hardwood at all in a new build or renovation. Check out the following alternatives:

• Recycled hardwoods have plenty of character and are especially strong and dry. They are put to great use to make all manners of floorboards, benchtops, shelving, cladding, decking boards, posts and sleepers. Bearer and joist sections for floor and deck framing are available too. Look in the Yellow Pages under Building Materials-Secondhand or on website such as Ecospecifier.  
• Salvaged timber come from felled urban and rural trees and is made available commercially by a few merchants. Much like recycled timber, this timber is best sourced on a project to project basis.
• Bamboo grows to maturity in three to six years and makes for very hard-wearing floors and furniture.  
• A number of brands now sell composite decking boards made of wood fibre and recycled plastic. They are a good maintenance-free replacement to solid hardwood. 
• Wood veneers, mostly used for panelling and furniture, can be made of printed poplar design to imitate expensive feature timbers.
• Plantation pine boards can be used where a durable and non-toxic alternative to MDF and particleboard is sought for shelving, architraves and skirting boards – finger jointed pine is best specified in this case as it makes good use of timber off cuts.
• Engineers when instructed to do so can specify composite floor trusses, laminated timber and plantation pine instead of structural hardwood. These are usually more economical to use too.

Last but not least, why not offset your hardwood use like your can your car or air travel? Check the tree-planting organizations online, they will be more than happy to receive your support in establishing and maintaining their native hardwood plantations.