types of WOOD – Wood has traditionally been classified into two primary categories: Hardwood (any leaf-bearing tree) and softwood (any cone-bearing tree). As with most other general classifications, this can get somewhat confusing due to the fact that there are some leaf-bearing trees that can have relatively soft wood, while some coniferous trees that can have rather hard wood.
- Generally speaking, however, hardwoods are by and large considered to be heavier and more dense than softwoods.
- Hardwoods are commonly used in the construction of walls, ceilings and floors, while softwoods are often used to make doors, furniture and window frames.
- Some examples of the most popular hardwoods include oak, maple, mahogany, cherry, walnut, and teak,
Commonly used softwoods include pine, hickory, beach, ash, birch, and cedar.
- 0.1 How wood is used in structure?
- 0.2 Why is wood still used in construction?
- 0.3 What are three ways that wood is used?
- 0.4 Why is wood better than concrete?
- 1 When was wood First used in construction?
- 2 What is the most common material used in construction?
What is the most common wood used in construction?
Oak wood – Oak wood is one of the most commonly used types of hardwood. It has a distinct grain finish and is used in a variety of applications. Oak wood has the following properties:
Heavy Strong Moisture resistant Fungus resistant Commonly used for household furniture such as bookshelves and cabinets
How wood is used in structure?
A structure must be designed to resist all the loads expected to act on the structure during its service life. Under the effects of the expected applied loads, the structure must remain intact and perform satisfactorily. In addition, a structure must not require an inordinate amount of resources to construct.
- Thus, the design of a structure is a balance of necessary reliability and reasonable economy.
- Wood products are frequently used to provide the principal means of structural support for buildings.
- Economy and soundness of construction can be achieved by using wood products as members for structural applications such as joists, wall studs, rafters, beams, girders, and trusses.
In addition, wood sheathing and decking products perform both a structural role by transferring wind, snow, occupant and content loads to the main structural members, as well as the function of building enclosure. Wood can be used in many structural forms such as light-frame housing and small buildings that utilize repetitive small dimension members or within larger and heavier structural framing systems, such as mass timber construction, which is often utilized for commercial, institutional or industrial projects.
- The engineered design of wood structural components and systems is based on the CSA O86 standard.
- During the 1980s, the design of wood structures in Canada, as directed by the National Building Code of Canada (NBC) and CSA O86, changed from working stress design (WSD) to limit states design (LSD), making the structural design approach for wood similar to those of other major building materials.
All structural design approaches require the following for both strength and serviceability: Member resistance = Effects of design loads Using the LSD method, the structure and its individual components are characterized by their resistance to the effects of the applied loads.
The NBC applies factors of safety to both the resistance side and the load side of the design equation: Factored resistance = Factored load effect The factored resistance is the product of a resistance factor (f) and the nominal resistance (specified strength), both of which are provided in CSA O86 for wood materials and connections.
The resistance factor takes into account the variability of dimensions and material properties, workmanship, type of failure, and uncertainty in the prediction of resistance. The factored load effect is calculated in accordance with the NBC by multiplying the actual loads on the structure (specified loads) by load factors that account for the variability of the load.
No two samples of wood or any other material are exactly the same strength. In any manufacturing process, it is necessary to recognize that each manufactured piece will be unique. Loads, such as snow and wind, are also variable. Therefore, structural design must recognize that loads and resistances are really groups of data rather than single values.
Like any group of data, there are statistical attributes such as mean, standard deviation, and coefficient of variation. The goal of design is to find a reasonable balance between reliability and factors such as economy and practicality. The reliability of a structure depends on a variety of factors that can be categorized as follows:
external influences such as loads and temperature change; modelling and analysis of the structure, code interpretations, design assumptions and other judgements which make up the design process; strength and consistency of materials used in construction; and quality of the construction process.
The LSD approach is to provide adequate resistance to certain limit states, namely strength and serviceability. Strength limit states refer to the maximum load-carrying capacity of the structure. Serviceability limit states are those that restrict the normal use and occupancy of the structure such as excessive deflection or vibration.
Ultimate limit states (ULS) are concerned with life safety and correspond to the maximum load-carrying capacity and include such failures as loss of equilibrium, loss of load-carrying capacity, instability and fracture; and Serviceability limit states (SLS) concern restrictions on the normal use of a structure.
Examples of SLS include deflection, vibration and localized damage. Due to the unique natural properties of wood such as the presence of knots, wane or slope of grain, the design approach for wood requires the use of modification factors specific to the structural behaviour.
These modification factors are used to adjust the specified strengths provided in CSA O86 in order to account for material characteristics specific to wood. Common modification factors used in structural wood design include duration of load effects, system effects related to repetitive members acting together, wet or dry service condition factors, effects of member size on strength, and influence of chemicals and pressure treatment Wood building systems have high strength-to-weight ratios and light-frame wood construction contains many small connectors, most commonly nails, which provide significant ductility and capacity when resisting lateral loads, such as earthquake and wind.
Light-frame shearwalls and diaphragms are a very common and practical lateral bracing solution for wood buildings. Typically, the wood sheathing, most commonly plywood or oriented strand board (OSB), that is specified to resist the gravity loading can also act as the lateral force resisting system.
This means that the sheathing serves a number of purposes including distributing loads to the floor or roof joists, bracing beams and studs from buckling out of plane, and providing the lateral resistance to wind and earthquake loads. Other lateral load resisting systems that are used in wood buildings include rigid frames or portal frames, knee bracing and cross-bracing.
A table of typical spans is presented below to aid the designer in selecting an appropriate wood structural system.
Why is wood still used in construction?
Environmental benefits of wood construction – Wood construction has multiple benefits in environmental terms. Among them, we will dress some of the most relevant:
- It is the only renewable and recyclable construction material, If the forest is managed sustainably, the trees can be a renewable resource. In addition, wood also requires less energy to be processed.
- It can absorb carbon, Wood accumulates large amounts of CO2 and its industrialization generates lower greenhouse gas emissions than other materials. For example, producing a ton of wood generates 33 kilos of net emissions, compared to 264 kilos for cement and 694 kilos for steel.
- Produce less waste, The use of wood generates less waste and speeds up construction times
- Greater energy efficiency, Wood contributes to energy efficiency due to its ability to conduct heat, which makes it a better insulator than other materials. In fact, it is 400 times better than steel and 15 times better than concrete.
In short, processed wood construction not only adds value by serving as an active absorbent of CO2, but also significantly reduces emissions linked to the industrial construction process. In addition, in this process costs and possible emissions are reduced because it is more efficient in terms of energy consumption.
Why is wood better for construction?
Tree-conomics. – Wood is a sustainable, high-value building material. Building with wood is efficient, often completed faster than other systems, and can be done year-round in almost any climate. Wood can often be locally sourced from North American forests and is frequently less expensive than alternative building materials.
What are three ways that wood is used?
A Story of Wood Wood has played an important role in the history of civilization. Humans have used it for fuel, building materials, furniture, paper, tools, weapons, and more. And demand for wood continues to increase annually, spurring conflicts between neighboring states over control of shared resources. Credit: Photo by, CC. Advertisement The DIY movement has firmly established itself, particularly when it comes to home improvement. On cable television, HGTV and the DIY Network feature non-stop programming on renovations that cover a range of projects and budgets.
A common element in many of the renovations is wood. People want it in their homes whether in the form of hardwood floors, high end kitchen cabinets, or a durable table. In my own home, we have a coffee table that we’ve had for 15 years. The wood bears the marks of the lives that have been lived around it—including a few watermarks since I am terrible about using coasters—and occasionally we talk about replacing it, but we never do.
It has character. And it’s a solid wooden table—we’d be crazy to give it up. Anyone who has ever tried to light a fire knows that there are two types of wood: softwoods and hardwoods. For fires, hardwoods will burn hotter and longer—important factors when you’re trying to ward off the chill—while softwoods will ignite more easily so it makes excellent kindling.
Softwoods are the source of about 80% of the world’s lumber so when we talk about wood, more often than not, we’re talking about softwoods. These woods include cedars, Douglas firs, cypresses, firs, junipers, kauris, larches, pines, hemlocks, redwoods, spruces, and yews. The wood from these trees tends to be more malleable.
However, the softwood/hardwood division is not concrete: some softwoods are harder than some hardwoods. The Douglas fir and the yew listed above, for example, are actually mechanically harder than several hardwoods. In general, softwoods tend to be far less expensive in comparison to hardwoods and are used more frequently in construction.
- Wood has played an important role in the history of civilization.
- Humans have used it for fuel, building materials, furniture, paper, tools, weapons, and more.
- And demand for wood continues to increase annually, spurring conflicts between neighboring states over control of shared resources.
- Our relationship to this resource has remained relatively unchanged over time, and our methods of developing and managing woodlands continue to rely on tried and true techniques established by early civilizations.
So perhaps this is why we take it for granted: wood has long been a part of our lives, and we probably can’t really imagine it not being there. The United States and the world’s timber supply Strong states and nations have typically had access to a generous timber supply that they draw upon liberally to further their own development.
These fortunate states have followed a similar pattern in the treatment of their lumber resources. First, they use their own virgin forests. Then they begin to barter with neighbors, and trade relations may be established for that purpose. Finally, they manage to cultivate timber for consumption, but may continue to import materials to supplement their stores from countries still possessing a lumber surplus.
This is the story in the lumber trade that echoes over centuries, from India to the Americas. It perpetuates a cycle of diminished resources that often leaves behind a trail of disenchantment and bitterness between industry and the citizens of the state or nation.
- The United States is still able to harvest timber from its own supply, but these resources are quickly being exhausted.
- To initial settlers in the seventeenth century, America seemed to be an endless forest—820 million acres to be exact.
- The export of timber products began in the early days of the Atlantic colonies, for several generations the forest was a barrier to settlement and migration rather than an economic resource.
A timber shortage seemed impossible. Lumber was chiefly transported by water: Logs moved down the Atlantic Coast from Maine to Boston, from the upper Hudson to New York, and from the shores of the Great Lakes into Buffalo and Chicago. With Maine, New York, and Pennsylvania leading lumber production and waterways being used to transport materials, lumber was cheap in the major markets of the country.
Softwoods were used for picket fences, boardwalks, paving blocks, windmills, pails, tubs, farm implements, and furniture. However, once these stores were depleted, and lumber manufacturing moved first to the Lake States and then to the South and then to the Pacific Coast, railways and trucks were increasingly required which increased the costs for the manufacturers and the consumers.
The rise of overland transport also increased competition for the foresters and lumber processors because it opened the markets to each other—eastern lumber markets were made available to western producers, and vice versa. The lumber market appeared to be expanding.
- Following World War II, the Assistant Chief of the U.S.
- Forest Service E.I.
- Otok suggested that America would be viewed as a source of timber for those European and Asian countries damaged by the war.
- He cautioned against accepting this responsibility and drew attention that American consumption of softwoods had been dampened by the war efforts and would quickly rebound as the nation looked toward development once more.
During the war, lumber had been designated a “critical” war material, and was consigned to cantonments, crating, dunnage, pallets, and general wartime construction. He estimated that Europe may need as much as six to ten billion board feet per year, and stressed that in the United States, millions of houses and farm buildings needed to be built and/or renovated.
But the needs of the war-worn nations bore consideration. Who did the North American forests belong to? Were they the sole possession of North America? Or were they a world resource that was meant to be shared with those countries in need? Kotok stressed the need to manage the forest resources so that all could benefit.
Healthy forest economies could provide more than timber products—for example, if foreign nations needed agricultural products, the United States could provide these commodities as well. Kotok could see little that the United States would not be able to provide to the redeveloping world that could not be aided by the management of the North American lumber supply.
- This strategy contributed to the position of the United States as a powerful leader following World War II.
- In emphasizing end-use forest products, manufacturers increased their offerings beyond lumber—both at home and abroad—to include beams, arches, prefinished paneling, insulation board, pre-primed siding, and precut pieces for furniture and toys.
Kotok’s caution seems well advised in light of the experience of developing nations like Haiti and much of Southeastern Asia. These areas have harvested their forests to meet the demands of external countries to the detriment of the forest industry and development within the nation, reaping devastating ecological change in the process.
The impact of deforestation Even as developing nations cut the softwoods under their control to participate in the global trade of this resource, it should be noted that the areas where these trees grow would be cleared in the course of development. In an ideal relationship, lumber trade should feed capital back into the nation to assist in sustained-yield practices.
However, demand usually outstrips production—both internally and externally. For example, growing populations need expanded areas for food activities, so forests are cleared for crops and ranching. Annual burnings often prevent forest regrowth, as does grazing by sheep, goats, and cattle.
- Wood fuels still remain widely used for domestic cooking and heating, brewing, baking, and brick making.
- And as oil prices rise, more people may be inclined to look to wood for fuel.
- Logging itself depletes forest stocks before they can be replenished.
- Regulated timber harvesting should not permanently damage the forest, but in many smaller nations, timber extraction is not monitored.
And as mentioned previously, without proper support any state management program is bound to fail—sustained-yield practices require support from local groups to be effective. Deforestation is therefore associated with rising population and the expansion of agriculture, and in the long-term harvesting of wood for fuel and export.
- It is a common phenomenon in developing countries, and one that places them in economic peril as they deplete their source of capital.
- Developing countries have increasingly developed programs in response to international pressure to preserve their resources and establish national priorities.
- However, these efforts have had mixed degrees of success: Forest reserves still suffer from illegal cutting and grazing, and local groups lack an understanding about soil conditions and rainfall requirements.
Though forests are widely distributed, they are not equitably distributed, and this has caused some dispute over the management, availability, and trade concerning forest resources. As evidenced by the case of the Indian forests under colonial rule, conflicts concerning these resources have long been a part of the history of lumber trade.
- The most recent and influential concerns the trade dispute between the United States and Canada.
- As the North American timber supplies diminish, the nation has turned increasingly to British Columbia for wood.
- North American foresters have argued that the Canadian lumber industry is unfairly subsidized by the federal and provincial governments.
This allows the price charged to harvest timber to be set by legislation rather than competitively, and in 1982 the U.S. claimed these practices undermined the market prices which tipped the scales commercially to Canada. This trade dispute has lingered for 24 years.
In 1996, the United States and Canada reached a five year trade agreement called the Softwood Lumber Agreement (SLA). The SLA limited Canadian exports to 14.7 billion board feet per year. The agreement expired on April 2, 2001 and neither party was able to reach an agreement for renewal. In fact, the United States renewed its request for tariffs, maintaining the United States lumber industry was under threat from the subsidized Canadian industry.
The dispute continued anew until February 2009 when the London Court of International Arbitration ruled that Canada was in breach of the SLA because quotas had not been calculated properly during January-June 2007. The London Court of International Arbitration ordered sawmills in the provinces of Ontario, Quebec, Manitoba, and Saskatchewan to pay an additional 10 per cent export charge.
- Given the dwindling reserves of softwoods, it is imperative the alternatives be found to meet our needs and further development.
- One potential answer to an alternative has been found by working with more abundant materials previously regarded as unusable, or as “weed” species to create structural particle board (SPB).
SPB is a reconstituted wood panel that is suitable for structural and exterior construction, which means it can be substituted for construction-grade plywood. It can be made from soft or low density hardwoods instead of the greatly diminished softwood supplies.
It’s possible that the growth of SPB may help reinvigorate lumber industries in places that have had to extensively rely on imports to sustain their lumber needs. In fact, though the early development and distribution of SPB has largely been controlled by the United States and Canada, SPB production has spread to other countries in Europe and Asia.
SPB has a low density and is resistant to damage, which may help nations that can acquire a surplus achieve an influential trade status. At the same time, the focus on SPB may allow depleted woodlands to make a recovery if they are managed properly. Allen, Julia C., and Douglas E.
Barnes. “The Causes of Deforestation in Developing Countries.” Annals of the Association of American Geographers 75(2) (June 1985): 163-184. Bengston, David N., Hans M. Gregersen, and John Haygreen. “Seesawing Across the Forty-Ninth Parallel: The International Diffusion of a Wood-Based Technology.” Journal of Forest History 32(2) (April 1988): 82-88.
Greeley, W.B. ” The Relation of Geography to Timber Supply.” Economic Geography 1(1) (March 1925): 1-14. Guha, Ramachandra. “The Prehistory of Community Forestry in India.” Environmental History 6(2) (April 2001): 213-238. Kohlmeyer, Fred W. “Lumber Distribution and Marketing in the United States.” Journal of Forest History 27(2) (April 1983): 86-91.
Otok, E.I. “America’s Role in Meeting World Timber Needs.” Proceedings of the American Philosophical Society 89(2) (July 1945): 418-422. Streyffert, Thorsten. “Softwood Resources of Europe.” Economic Geography 10(1) (January 1934): 1-13. The views expressed are those of the author(s) and are not necessarily those of Scientific American.
Discover world-changing science. Explore our digital archive back to 1845, including articles by more than 150 Nobel Prize winners. : A Story of Wood
What is the most important use of wood?
Read a brief summary of this topic – wood, the principal strengthening and nutrient-conducting tissue of trees and other plants and one of the most abundant and versatile natural materials. Produced by many botanical species, including both gymnosperms and angiosperms, wood is available in various colours and grain patterns.
- It is strong in relation to its weight, is insulating to heat and electricity, and has desirable acoustic properties.
- Furthermore, it imparts a feeling of “warmth” not possessed by competing materials such as metals or stone, and it is relatively easily worked.
- As a material, wood has been in service since humans appeared on Earth.
Today, in spite of technological advancement and competition from metals, plastics, cement, and other materials, wood maintains a place in most of its traditional roles, and its serviceability is expanding through new uses. In addition to well-known products such as lumber, furniture, and plywood, wood is the raw material for wood-based panels, pulp and paper, and many chemical products.
Why is wood better than concrete?
Sustainability and the Environment – When we think of wood, we often imagine a natural, sustainable, and environmentally friendly building material. And in many ways, it is. Wood stores carbon dioxide, which results in a reduction of carbon dioxide emissions by 2,432 metric tonnes (equal to taking 500 cars off the road for a year).
- In contrast, concrete is often criticized for being unsustainable as it takes a lot of resources to produce.
- Cement, which we learned is a main component of concrete, is one of the world’s biggest contributors to greenhouse gas emissions.
- Many people assume that because cement production is bad for the environment, so is concrete production.
However, the truth is far more complicated than that. Let’s take a closer look
- Concrete is durable —its lifespan is actually two or three times longer than other common building materials.
- Concrete is great at absorbing and retaining heat, which means it will increase the energy efficiency of a building and reduce HVAC expenses.
- Its reflective properties will decrease air-conditioning costs in the hot summer months.
- Concrete produces little waste as it can be produced in batches specific to project needs.
What are two importance of wood?
#3. Wood is an important building material – Wood is a reliable construction material with long service life. With many valuable properties like small bulk density, aesthetic working properties, and high strength, wood is the most famous construction material.
Where is wood mostly used?
Distinction – In the narrow sense of the terms, wood, forest, forestry and timber/lumber industry appear to point to different sectors, in the industrialized, internationalized world, there is a tendency toward huge integrated businesses that cover the complete spectrum from silviculture and forestry in private primary or secondary forests or plantations via the logging process up to wood processing and trading and transport (e.g.
- Timber rafting, forest railways, logging roads ).
- Processing and products differs especially with regard to the distinction between softwood and hardwood,
- While softwood primarily goes into the production of wood fuel and pulp and paper, hardwood is used mainly for furniture, floors, etc.
- Both types can be of use for building and (residential) construction purposes (e.g.
log houses, log cabins, timber framing ).
When was wood First used in construction?
Wood is one of the longest standing building materials in existence, with evidence showing homes built over 10,000 years ago used timber as a primary source for construction materials. Europe’s Neolithic long house-a long, narrow timber dwelling built in 6000 BC- is an excellent example.
- As one of the largest buildings during that period, the Neolithic long house was solid and massive, with a capacity of housing around 30 people.
- Since then, the discovery of different elements such as bronze and steel have changed and improved the way wood is applied to building construction.
- Wood continues to be used to create both modest buildings such as the log cabin, and impressive structures such as Chinese temples.
Boasting its environmentally friendly, renewable and extremely durable features, wood remains an extremely popular choice for both buildings and furnishings. Take a look at the Living with Wood: From the Beginning of Time infographic below to learn more about the history of wood and homes. Infographic courtesy of logcabinhub.com
What is wood used for short answer?
Wood is used in: making table, chair, door, bed,etc. as a source of fuel.
How much wood is used in construction?
Hardwood floors, cabinets, siding, roofing, paneling etc. could more than double the number of trees needed to complete the home. In total, building a home today will consume forty-four mature trees for every 2600 square feet. Be sure to include the garage when adding up your square footage.
What are 3 common hardwoods?
Common Hardwood Trees – Treehugger / Hilary Allison Unlike softwood varieties, hardwood trees have evolved into a broad array of common species. The most common species in North America are oaks, maple, hickory, birch, beech, and cherry. Forests in which a majority of the trees drop their leaves at the end of the typical growing season are called deciduous forests.
Ash ( Fraxinus ) Beech ( Fagus ) Basswood ( Tilia ) Birch ( Betula ) Black cherry ( Prunus ) Black walnut/butternut ( Juglans ) Cottonwood ( Populus ) Elm ( Ulmus ) Hackberry ( Celtis ) Hickory ( Carya ) Holly ( IIex ) Locust ( Robinia and Gleditsia ) Magnolia ( Magnolia ) Maple ( Acer ) Oak ( Quercus ) Poplar ( Populus ) Red alder ( Alnus ) Royal paulownia ( Paulownia ) Sassafras ( Sassafras ) Sweetgum ( Liquidambar ) Sycamore ( Platanus ) Tupelo ( Nyssa ) Willow ( Salix ) Yellow-poplar ( Liriodendron)
What is the most common material used in construction?
1. Concrete – Concrete is the most widely used building material in the world, making it a good starting material to get to know. However it also has significant environmental impacts, including a carbon footprint of up to 5% of worldwide emissions. To get to know all about designing with concrete, the Concrete Center has a collection of useful reports, many of which are free with registration. Translucent wood developed by KTH Royal Institute of Technology in Stockholm. Image © Peter Larsson / KTH
What is the most common hard wood?
Red Oak – As by far the most abundant domestic hardwood, it is no wonder that Oak in general is also the most popular choice for flooring in this country, and Red Oak in particular. Besides being abundant, and consequently more affordable, Red Oak is one of the most stain-friendly woods around.
This means that you can create whatever look you want without breaking the bank, and can change the look later with a simple sand a refinish. Red Oak typically displays moderate to heavy graining with modest color variations. Its natural color tends to range from light creamy reddish pinks (hence “Red” Oak) to shades of brown.
And, with a Janka rating of about 1290, Red Oak tends to hold up well under wear but be flexible enough to not crack and split under pressure.