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Some of the most important building materials are: timber, brick, stone, concrete, metal, plastics and glass.

Timberis provided by different kinds of trees. Timbers used for building purposes are divided into two groups called softwoods and hardwoods. Timber is at present not so much used in building con­struction, as in railway engineering, in mining and in the chemical industry where it provides a number of valuable materials.

However, timber is still employed as a building material in the form of boards. For the interior of buildings plywood and veneer serve a number of purposes.

A brickis best described as a "building unit". It may be made of clay by moulding and baking in kilns, of concrete, of mortar or of a composition of sawdust and other materials. In shape it is a rectan­gular solid and its weight is from 6 1/2 to 9 Ib.

There exists variety of bricks for different purposes: ordinary, hollow or porous, lightweight, multicolor bricks for decorative pur­poses, etc. Bricks are usually laid in place with the help of mortar.

The shape and convenient size of brick enables a man to grip it with an easy confidence and, because of this, brick building has been popular for many hundreds of years.

Sometimes natural stones such as marble, granite, basalt, lime­stone and sandstone are used for the construction of dams and foun­dations. Marble, granite and sandstone are widely used for decora­tive purposes as well, especially with the public buildings.

Metals: Aluminium, principally in the form of various alloys, is highly valued for its durability and especially for its light weight, while brass is frequently used for decorative purposes in facing.

Steelfinrods its use in corrugated sheets for roofing, for girders, frames, etc. Various shapes are employed in construction.

Plastics are artificial materials used in construction work for a vast number of purposes. Nowadays plastics, which are artificial materials, can be applied to almost every branch of building, from the laying of foundation to the final coat of paint. Synthetic resins are the main raw material for plastics. Plastics have some good ad­vantages as they are lighter than metals, not subject to corrosion, and they can be easier machined. Besides, they are inflammable, they can take any color and pattern, and they are good electrical insulators. More over, they possess a high resistance to chemical action.

A lot of decorative plastics, now available, have brought about a revolution in interior and exterior design. But plastics are used now not only for decoration. These materials are sufficiently rigid to stand on their own without any support. They can be worked with ordinary builders' tools.

Laminateis a strong material manufactured from many layers of paper or textile impregnated with thermosetting resins. This sand­wich is then pressed and subjected to heat. Laminate has been developed for both inside and outside use. It resists severe weather condi­tions for more than ten years without serious deformation. As a struc­tural material it is recommended for exterior work. Being used for surfacing, laminate gives the tough surface.

Foamed glassis a high-porosity heat insulating material, avail­able in block made of fine-ground glass and a frothing agent.

Foamed glass is widely used in prefabricated house building, to ensure heat insulation of exterior wall panels, and in industrial con­struction.

Foamed glass has a high mechanical strength, is distinguished by moisture, vapor and gas impermeability. It is non-inflammable, offers resistance to frost, possesses a high sound adsorption, and it is easily sawn and nailed.

Structural foamed glass blocks were designed to fill ceilings, and for making interior partitions in buildings and rooms, to ensure heat and sound insulation.

For insulation mineral wool or cinder wool is often resorted to.

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