The most advanced building material is wood Building Material is Wood according to Clay Risen in the March 2014 issue of Popular Science magazine. Source: The Calaveras Enterprise
Mr Risen said that engineered wood is superior in almost all respects to steel and concrete.
The essay praises cross-laminated timber, or CLT.
Wood is very strong in the direction of the grain but is much weaker cross-grain. A CLT beam begins with a board of the desired length and height to which a layer of shorter pieces is added at a 90-degree angle.
This process stiffens and strengthens the beam. Opposing grain layers of wood are added and glued together until a timber of the desired width is obtained.
Conventional wood-frame construction is likely to continue as the preferred method of erecting residences, as it is economical and satisfactory.
The problem is that fire readily spreads to other buildings. Most towns in the Mother Lode suffered one or more disastrous conflagrations, which is the primary reason brick and stone construction became dominant in business districts.
Naturally, the fire danger was not confined to small towns. Chicago and San Francisco are just two of many examples of infernos that resulted in widespread devastation and loss of life.
Another major problem with conventional wood-frame construction is it lacks strength and stability when used in buildings more than a few stories high. Thus, for tall buildings, steel beams combined with reinforced concrete became favored for the strength and fire resistance.
For multistory buildings, CLT construction solves the problems associated with conventional wood-frame construction.
Individual CLT panels of single-story height are assembled in a factory, providing computerized accuracy. Window and door openings are precut.
Other units can be stacked and fastened on top of the first, allowing multiple stories to be lifted into position with a crane.
A 10- story apartment building has been completed in Australia, and Sweden has approved a 34-story tower for construction in Stockholm.
CLT beams allegedly have strength comparable to steel. As for fire hazard, the interior panels are usually covered with a layer of fire-resistant gypsum.
Materials resistant to flame may also cover the exterior wood surfaces. Cross-laminated timbers are reportedly safer in a fire than steel.
Thick wood beams char on the outside, providing resistance to deeper burning, while extreme heat causes steel to bend and collapse.
The World Trade Center is one example. Steel and concrete require far more energy to produce than wood and the production generates massive quantities of carbon dioxide – aka, greenhouse gas.
While some carbon dioxide is created during logging and lumbering operations, a tree’s growth depends on and “absorbs” carbon dioxide from the air during its growth cycle.
CLT construction results in a lighter building and thus, requires less concrete for a foundation. Other cost savings have added up to an average price reduction of about 15 percent.
In addition to wood construction being environmentally friendlier than steel and concrete, it has far better insulating qualities than the other two, resulting in lower heating and cooling costs.
CLT was developed in Austria in the 1990s as a result of the country having overcrowded forests, resulting in unhealthy trees due to insufficient water and nutrients.
According to an article in The New York Times on June 4, 2012, Austria was producing around 80% of the world’s CLT panels. So the Austrian government and timber industry, working together, alleviated a problem and created a superior building material.
The article stated that CLT construction was popular in Europe but just gaining a foothold in North America.
There is a company in Montana producing CLT panels. Others will surely follow.
The country has an excess of timber, as confirmed by Steve Marshall, the assistant director of cooperative forestry for the US Forest Service when he said: “A lot of forests in the US are vastly overstocked with fuel.”
And while Marshall’s observation was included in an article making an environmental case for the latest clean-burning wood heaters, it should be clear our forests are overcrowded.
Some environmental groups realize timber harvesting can produce healthier forests. If politicians were courageous enough to ignore the loud minority of radical preservationists who continue to throw roadblocks in the path of responsible forest management, we could have cleaner air quality, more efficient buildings and jobs for many thousands of unemployed or underpaid ex-loggers.
As a bonus, we would also have forests not so overgrown with brush and trees that a person cannot walk through them.
