Pre-cut studs save a framer much time, because they are pre-cut by the manufacturer for use in 8-, 9-, and 10-foot ceiling applications, which means the manufacturer has removed a few inches or centimetres of the piece to allow for the sill plate and the double top plate with no additional sizing necessary.
Dimensional lumber is available in green, unfinished state, and for that kind of lumber, the nominal dimensions are the actual dimensions.
Individual pieces of lumber exhibit a wide range in quality and appearance with respect to knots, slope of grain, shakes and other natural characteristics. Therefore, they vary considerably in strength, utility, and value.
Hardwoods cut for furniture are cut in the fall and winter, after the sap has stopped running in the trees. If hardwoods are cut in the spring or summer the sap ruins the natural color of the timber and decreases the value of the timber for furniture.
Defects occurring in lumber are grouped into the following four divisions:
During the process of converting timber to commercial form the following defects may occur:
Wood with less than 25% moisture (dry weight basis) can remain free of decay for centuries. Similarly, wood submerged in water may not be attacked by fungi if the amount of oxygen is inadequate.
Under proper conditions, wood provides excellent, lasting performance. However, it also faces several potential threats to service life, including fungal activity and insect damage – which can be avoided in numerous ways. Section 2304.11 of the International Building Code addresses protection against decay and termites. This section provides requirements for non-residential construction applications, such as wood used above ground (e.g., for framing, decks, stairs, etc.), as well as other applications.
There are four recommended methods to protect wood-frame structures against durability hazards and thus provide maximum service life for the building. All require proper design and construction:
Wood is a hygroscopic material, which means it naturally absorbs and releases water to balance its internal moisture content with the surrounding environment. The moisture content of wood is measured by the weight of water as a percentage of the oven-dry weight of the wood fiber. The key to controlling decay is controlling moisture. Once decay fungi are established, the minimum moisture content for decay to propagate is 22 to 24 percent, so building experts recommend 19 percent as the maximum safe moisture content for untreated wood in service. Water by itself does not harm the wood, but rather, wood with consistently high moisture content enables fungal organisms to grow.
For buildings in termite zones, basic protection practices addressed in current building codes include (but are not limited to) the following:
There are two basic methods of treating: with and without pressure. Non-pressure methods are the application of preservatives by brushing, spraying, or dipping the piece to be treated. Deeper, more thorough penetration is achieved by driving the preservative into the wood cells with pressure. Various combinations of pressure and vacuum are used to force adequate levels of chemical into the wood. Pressure-treating preservatives consist of chemicals carried in a solvent. Chromated copper arsenate, once the most commonly used wood preservative in North America began being phased out of most residential applications in 2004. Replacing it are amine copper quat and copper azole.
Biomass is already an important source of energy for the North American forest products industry. It is common for companies to have cogeneration facilities, also known as combined heat and power, which convert some of the biomass that results from wood and paper manufacturing to electrical and thermal energy in the form of steam. The electricity is used to, among other things, dry lumber and supply heat to the dryers used in paper-making.
Lumber is a sustainable and environmentally friendly construction material that could replace traditional building materials (e.g. concrete and steel). Its structural performance, capacity to fixate CO2 and low energy demand during the manufacturing process make lumber an interesting material.
The circular economy can be considered as a model that aims to eliminate waste by targeting materials, and products at their maximum value of utility and time. In short, it is a whole new model of production and consumption that ensures sustainable development over time. It is related to the reuse of materials, components, and products over a longer life cycle.
Wood waste can be recycled at its EoL to make new products. Recycled chips can be used to make wood panels, which is beneficial for both the environment and industry. Such practice reduces the use of virgin raw materials, eliminating emissions that would have otherwise been emitted in its manufacturing.
The term secondary raw material denotes waste material that has been recycled and injected back into use as productive material. Lumber has a high potential to be used as a secondary raw material at various stages, as listed below:
Timber undergo multiple processing stages before lumber of desired shapes, size, and standards are achieved for commercial use. The process generates a lot of waste which in most cases is disregarded. But being an organic waste, the positive aspect of such waste is that it can be used as a fertiliser or to protect the soil in severe weather conditions.
Waste generated during the manufacturing of lumber products can be used to produce thermal energy. Lumber products after their end-of-life can be downcycled into chips and be used as . It is very beneficial for industries that need thermal energy.