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The renewable resource of wood has recently been attracting a great deal of public attention as an ecological and environmentally friendly material for the earth. Wood has superior characteristics in the strength per unit weight of the mass, fire resistance, heat insulation and retaining, humidity conditioning, etc. The glulam is an epoch-making building material in which these superior characteristics of wood are scientifically and integrally packed for even better qualities as a non-structural as well as structural material.

The glulam products are used mainly as load-bearing structural members such as posts, beams, girders, arches, etc. In recent years, the glulam has become an indispensable engineered wood for building residential houses, gymnasiums, assembly halls, exhibition halls, bridges, etc. which require the use of structural materials with high performances in strength, fire resistance, durability, etc. The structural glulam products have strength classifications in accordance with the Notification of the Ministry of Land, Infrastructure, Transport and Tourism of the Government of Japan.

Glulam products in large dimensions which are “scientifically created” wood products, while retaining the merits of natural wood, have made it possible to construct new types of timber framed structures.

Compared with the other types of conventional structures, heavy timber structures of glulam can create totally new interior environments and designs, which are often talked about by many people impressed with the structures.

About 1.5 times stronger than solid wood
Because of the fact that glulam products are made from the laminae of natural wood without problematic defects, their qualities are stable and even. In addition, the laminae are glued together with such a superior glue as resorcinol resin glue, the strengths of glulam products are about 1.5 times greater than those of solid wood products.

Stronger than steel and concrete
Compared with other materials, the strengths per unit of the mass of such solid softwood as a Japanese cedar are much greater than others: in tensile strength, about 4 times of that of steel, and in compressive strength, about 5 times of that of concrete. Glulam products have even greater strengths. This means that the weights of timber framed structures can be much lighter than those of steel or RC structures.

Resistant to fire
During fire, steel frames soften when they are heated to 500…800 ℃ and eventually they will start to droop and melt down. On the other hand, although wood frames can burn, if the sectional dimensions are large, only surface layers burn and leave charred layers, preventing the supply of oxygen into internal layers of wood. Even when the wood is heated to 1,000 ℃, the speed of charring of wood layers is slow, hence the required strength of wood frames is sustained. In 1993, heavy timber structures of glulam in large dimensions were approved as quasi-fire-resistant structures by the Ministry of Construction of the Government of Japan.

Warm in winter and cool in summer
The distinguished character of wood is that it does not transfer heat easily. The coefficient of heat transfer of wood is only 1/200 of that of steel and 1/4 of that of concrete. As wood is a good heat insulation material, in wood houses, the temperatures of wood elements do not change suddenly even when outside air temperatures change suddenly and radically, making it possible to provide the ideal living conditions with cool rooms in summer, and warm rooms in winter.

Strong against attacks from salt, acid and alkaline contents
Wood is strong against salt damages. Wood houses and buildings are suitable for use for constructing fish market shelters, seaside clubhouses, fishery port facilities and coastal facilities, etc. In addition, wood is strong against acid and alkaline contents, and exhaust gases, and wood is used to construct chemical plants, farm facilities, bridges, footbridges, etc.

Gentle to human eyes and ears
Wood can absorb unpleasant sounds in the very high and low tones. Buildings requiring acoustic performances such as concert halls, multi-purpose halls, churches, can best be constructed with heavy timber frames of glulam. In addition, wood can absorb ultraviolet rays, preventing eyestrain.

Natural humidity conditioning
Wood can breathe. During the summer and rainy seasons, when humidity is high, wood absorbs water contents from air, and during the winter season, wood emits water contents into air. Wood is suitable for use as non-structural and structural elements of indoor swimming pools and indoor sports facilities.

Highly flexible in profiling & dimensioning
Glulam products can be made in various profiles, thicknesses, widths and lengths. Also, it is possible to make them in complicated shapes such as arches. Designers have wider possibilities in planning and designing structures, and new architecture can be created.

Highly durable - semi permanent material
The high durability of wood is evident when we see ancient wood structures of Japan. The modern technology of gluing has advanced in recent years, and the durability of glue of at least 50 years can be guaranteed now.

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