A view to renew
Timber is a truly renewable window framing material that offers sustainability benefits. Gary Smith reports.
The first and most basic step in designing and building a house is to place it strategically on the site.
Site placement relates closely to aesthetics and marketability. More importantly, it allows the designer to use passive solar energy – frequently beaming through windows – as efficiently as possible.
This article is the second in a series on the materials used in manufacturing windows and doors, and the focus is on timber.
Easy to fabricate into virtually any shape and size, timber is nature’s insulator and a truly renewable building material.
Internationally, forests are being managed to ensure that there’s always a supply of timber. Trees are renewable but forests are not. So it is important for timber to be sourced responsibly.
The Forest Stewardship Council (FSC) management Standards allow businesses and individuals to support responsible management of forests by choosing FSC certified timber.
It takes less energy to create timber windows and doors than it takes for aluminium, steel or uPVC versions.
Trees are either softwoods (gymnosperms, or conifers with needles) or hardwoods (angiosperms, or flowering plants with leaves).
Softwoods are not always softer than hardwoods. The Australian cypress pine is a softwood of greater density and hardness than many hardwoods, and balsa is classified as a hardwood.
Timber’s most visible asset lies in its beauty, warmth and style, providing a dramatic and exciting touch throughout a dwelling. Architects and designers often choose timber for floors, walls, doors and windows. The reasons for this go beyond ‘the look’.
In addition to the general appeal of timber’s look and feel, the structure of wood is not thermally conductive, providing greater dimensional stability. The microscopic structure resembles a bundle of straws glued together – each ‘straw’ representing a cell with a cellulose wall and hollow centre (lumen), and lots of fine perforations through the walls.
The cell walls are impregnated with lignin, a natural polymer that glues the cells together and gives wood its strength.
Host of advantages
Whether timber windows and doors are stained to bring out the warm tones or painted to suit a particular decor, they will match or complement most architectural styles.
Timber provides natural insulation, whereas metals are natural heat conductors.
A well-constructed timber window or door coupled with good weather stripping provides the best possible barrier to heat or cold. Today’s modern timber windows, with high-performance glazing, contribute substantially to energy efficiency in dwellings.
Timber windows and doors don’t rust or corrode, no matter how harsh the environment. They can be cleaned easily by simply washing and, if need be, can be completely refinished. Furthermore, modern preservative treatments ensure longer life than ever before.
There have been important performance improvements in timber windows over the past 15 years. Most manufacturers now take advantage of the new high-technology seals that compensate for timber’s natural expansion and contraction.
Because of timber’s ability to reduce noise, increase energy efficiency and eliminate water penetration (previously the Achilles heel), it has performance characteristics equal to any other window material.
This development, coinciding with designers’ preference for thicker and bulkier looking windows, has helped timber to maintain a 25% market share nationally. The share is particularly strong on the east coast off Australia.
Western red cedar is a popular species used by the larger window manufacturers. However, this varies between states. Queensland uses substantial quantities of New Guinea Rosewood, and Victoria still favours the hardwoods meranti and Victorian ash.
Tighter OH&S regulations and the gradual loss of skilled tradespeople have brought many manufacturers to a crucial turning point. The innovative companies have invested in automation that allows them to maintain high quality and stay competitive.
Sustainability is of increasing importance to everyone. However, its definition is still the subject of wide debate, particularly in the building industry.
Timber is one of the most environmental friendly building materials, and this attribute contributes much to building sustainability.
Wood has been recognised globally as one response to climate change, as it stores carbon and reduces emissions into the atmosphere.
Once installed, timber windows and exterior doors should be coated to retain their appearance and ensure durability.
Interior and exterior surfaces are easily coated with a wide range of protective products such as acrylic or solvent-based paints, stains and oils.
For interior surfaces, protection is generally a straightforward process, particularly as the timber is usually seasoned and free of surface impurities that may hamper the coating process.
Exterior surfaces are exposed to heat, cold, ultra-violet radiation, water and airborne contaminants before and during coating. The coating protects against the elements and provides an appealing finish.
Selecting the correct coating product is crucial. Each timber species has characteristics that could affect the application of certain products. It is important to know a bit about the timber being coated, and the literature from coating product manufacturers will contain recommendations.
*This article first appeared in the summer 2018 edition of Building Connection. Click here to subscribe.