Building with Timber
Key Properties of Timber
Naturally Chemical-Free - pest- and rot-resistance achieved through careful detailing and timber choice
Fire Resistance - can be achieved through the use of large section timbers
Vapour-permeable/Breathable - for excellent indoor air quality and longevity of building fabric
Structure - natural timber is suitable for frames up to three storeys. The sky is the limit with engineered timber
Better-than-zero-carbon - a net sequestration of atmospheric carbon in hempcrete
Flexibility - suitable for domestic or commercial new build and retrofit projects
Renewable Resource - locally available and can be sustainably managed
Different Uses and Contexts
Timber can be used throughout the building, in some cases from foundation right up to roof covering, but it is most commonly used in the structural frame and internal finishes.
Frames can be joined together in many different ways e.g. traditional cut joints such as mortice and tenon, nuts and bolt connections, or the amazingly intricate joinery of the Japanese techniques.
As well as many different types of frames, timber is widely used for internal fittings and fixtures, and even in non-timber-framed buildings, wood can easily be added to create internal divisions, openings, finishes and fixtures. The nice warm look, feel and smell of wood softens interiors.
Wood can also now be used to insulate your property, in the form of recycled wood fibre board or blown cellulose insulation, showing the wide diversity of uses of this abundant natural material.
Materials and Process
There are two categories of timber, hardwood and softwood. Make sure you choose the most suitable timber to build with, whether the building is for public or commercial use, or your own house, as each species of timber has its own characteristics and durability. You can also choose from kiln dried or green; green timber being freshly sawn and having different working characteristics and cost.
A tree can be cut into planks to create square timbers or left “in the round” improving strength and creating less waste. Squared and round timber types are processed differently but can be used together.
Multiple planks can be glued together to create engineered beams, called glulam which can also be glued over a curved former to make a large curved beams. Multiple thinner planks or batons can be placed over each other and clamped where they cross over this method is called a Grid Shell, this method uses a minimal volume of timber to create a large indoor area.
Timber is widely understood in the construction industry although processes like round wood framing and green woodworking are specialist skills. Recycled wood fibres are used to create insulating products that are now well-established on the market.
Specifiers need to understand the special nature of timber, whether cut at site or supplied as a sawn, treated product. The time taken to assemble specialist frame types and the skilled labour force required should be considered, as should the drying time of green timber. For these techniques some expert advice is invaluable.
Timber absorbs a phenomenal quantity of CO2, sequestering vast amounts of this climate altering gas. It can work in harmony with all the other natural building materials, enhancing the beauty, complexity or simplicity of the finishes. As with most natural building technologies, a timber built house - once assembled - could be dismantled the day after completion and rebuilt in another location, leaving no waste.