Glued laminated timber, also called Glulam, is a type of structural timber

Timber

Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...

 product composed of several layers of dimensioned timber bonded together with durable, moisture-resistant adhesives. This material is called 'laminating stock' or lamstock for short.

By laminating several smaller pieces of timber

Timber

Timber may refer to:* Timber, a term common in the United Kingdom and Australia for wood materials * Timber, Oregon, an unincorporated community in the U.S...

, a single large, strong, structural member is manufactured from smaller pieces. These structural members are used as vertical column

Column

A column or pillar in architecture and structural engineering is a vertical structural element that transmits, through compression, the weight of the structure above to other structural elements below. For the purpose of wind or earthquake engineering, columns may be designed to resist lateral forces...

s or horizontal beam

Beam (structure)

A beam is a horizontal structural element that is capable of withstanding load primarily by resisting bending. The bending force induced into the material of the beam as a result of the external loads, own weight, span and external reactions to these loads is called a bending moment.- Overview...

s, as well as curved, arched shapes. In fact, glulam is the only engineered wood product that can be produced in curved shapes, offering unlimited design flexibility. It is available in a range of appearance characteristics to meet end-use requirements. Connections are usually made with bolts or plain steel dowels and steel plates

Tie (engineering)

A tie, structural tie, connector, or structural connector is a structural component designed to resist tension. It is the opposite of a strut, which is designed to resist compression. Ties are generally made of galvanized steel...

.

Glulam optimizes the structural values of a renewable resource - wood. Because of their composition, large glulam members can be manufactured from a variety of smaller trees harvested from second- and third-growth forests and plantations. Glulam provides the strength and versatility of large wood members without relying on the old growth-dependent solid-sawn timbers.
It reduces the overall amount of wood used when compared to solid sawn timbers by diminishing the negative impact of knots and other small defects in each component board.

Glulam has much lower embodied energy

Embodied energy

Embodied energy is defined as the sum of energy inputs that was used in the work to make any product, from the point of extraction and refining materials, bringing it to market, and disposal / re-purposing of it...

 than reinforced concrete and steel, although of course it does entail more embodied energy than solid timber. However the laminating process allows timber, to be used for much longer spans, heavier loads and complex shapes. Glulam is two-thirds the weight of steel and one sixth the weight of concrete – the embodied energy to produce it is six times less than the same suitable strength of steel. Glulam can be manufactured to a variety of straight and curved configurations so it offers architects artistic freedom without sacrificing structural requirements. Wood has a greater tensile strength relative to steel – two times on a strength-to-weight basis – and has a greater compressive resistance strength than concrete.
The high strength and stiffness of laminated timbers enable glulam beams and arches to span large distances without intermediate columns, allowing more design flexibility than with traditional timber construction. The size is limited only by transportation and handling constraints.

Glulam versus steel

A 2002 case study comparing energy use, greenhouse gas emissions and costs for roof beams found it takes two to three times more energy and six to twelve times more fossil fuels to manufacture steel beams than it does to manufacture glulam beams. It compared two options for a roof structure of a new airport in Oslo, Norway – steel beams and glulam spruce wood beams. The life cycle greenhouse gas emission is lower for the glulam beams. If they are burned at the end of their service life, more energy can be recovered than was used to manufacture them. If they are landfilled, the glulam beams result in greater greenhouse gas emissions than the steel beams. The cost of the glulam beams is slightly lower than the steel beams.

History

One of the earliest still-standing glulam roof structures is generally acknowledged to be the assembly room of King Edward College, a school in Southampton

Southampton

Southampton is the largest city in the county of Hampshire on the south coast of England, and is situated south-west of London and north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest...

, England, dating from 1870. Two churches near Liverpool

Liverpool

Liverpool is a city and metropolitan borough of Merseyside, England, along the eastern side of the Mersey Estuary. It was founded as a borough in 1207 and was granted city status in 1880...

, England are now thought to have the earliest extant uses: St Luke, Formby

Formby

Formby is a town and civil parish in the Metropolitan Borough of Sefton in Merseyside, England. It has a population of approximately 25,000....

 dates from 1855, and Holy Trinity, Parr Mount, St Helens

St Helens, Merseyside

St Helens is a large town in Merseyside, England. It is the largest settlement and administrative centre of the Metropolitan Borough of St Helens with a population of just over 100,000, part of an urban area with a total population of 176,843 at the time of the 2001 Census...

 from 1857. Other examples of 19th-century British glulam have also been identified. The first industrial patented use was in Weimar, Germany. Here in 1872 Otto Hetzer set up a steam sawmill and carpentry business in Kohlstrasse. Beginning in 1892, he took out a series of patents. DRP No. 63018 was for a ventilated timber floor deck that could be tightened laterally after installation, to compensate for shrinkage. Hetzer continued to patent various ingenious systems, but the first of these that could be compared with subsequently standardised horizontal glulam was DRP No. 197773, dated 1906. This entailed vertical columns which transitioned into curved glued laminated eaves zones, and then became sloped rafters, all in a single laminated unit. Each component, bonded under pressure, comprised three or more horizontally arranged laminations. In other words, the glulam portal frame was born. In 1895, Hetzer moved his company to Ettersburger Strasse, still in Weimar. At the height of production, in around 1917, he employed about 300 workers, and Müller includes a fine engraving of the railway sidings and works in 1921.
In 1909, the Swiss engineering consultants Terner & Chopard purchased permission to use Hetzer's patent, and employed glulam in a number of projects. These included the former Hygiene Institute, Zurich, 1911, now the main building of the university, where the bell-shaped roof dome is still to be seen.

The technology arrived in North America in 1934 when Max Hanisch, Sr., who had worked with Hetzer at the turn of the century, formed a firm in Peshtigo, Wisconsin to manufacture structural glued laminated timber. One of the first glulam structures erected in the United States was a research laboratory at the USDA Forest Products Laboratory in Madison, Wisconsin. The structure was erected in 1934 and is still in service today. A significant development in the glulam industry was the introduction of fully water-resistant phenol-resorcinol adhesive in 1942. This allowed glulam to be used in exposed exterior environments without concern of gluline degradation. The first U.S. manufacturing standard for glulam was Commercial Standard CS253-63, which was published by the Department of Commerce in 1963. The most recent standard is ANSI/AITC Standard A190.1-02, which took effect in 2002.

The roof of the Richmond Olympic Oval, built for speed skating events at the 2010 Winter Olympic Games in Vancouver, British Columbia, features is one of the world's largest clearspan wooden structures. The roof includes 2,400 cubic metres of Douglas-fir lamstock lumber in glulam beams. A total of 34 yellow-cedar glulam posts support the overhangs where the roof extends beyond the walls.

The roof of the Centre Pompidou-Metz museum is composed of sixteen kilometers of glued laminated timber. It represents a 90-metre wide hexagon with a surface area of 8,000 m². The glued laminated timber motif forms hexagonal wooden units resembling the cane-work pattern of a Chinese hat.

Glulam bridges

Pressure-treated glulam timbers or timbers manufactured from naturally durable wood species are well suited for creating bridges and waterfront structures. Wood’s ability to absorb impact forces created by traffic and its natural resistance to chemicals, such as those used for de-icing roadways, make it ideal for these installations. Glulam has been successfully used for pedestrian, forest, highway, and railway bridges. An example in North America of a glulam bridge is at Keystone Wye, South Dakota, constructed in 1966 - 7.

The Kingsway Pedestrian Bridge in Burnaby, British Columbia, Canada, is constructed of cast-in-place concrete for the support piers, structural steel and glulam for the arch, a post tensioned pre-cast concrete walking deck, and stainless steel support rods connecting the arch to the walking deck.

See also

• Engineered wood
  Engineered wood
  Engineered wood, also called composite wood, man-made wood, or manufactured board; includes a range of derivative wood products which are manufactured by binding the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials...
  
  
• Fiberboard
  Fiberboard
  Fiberboard is known as low density fiberboard is a type of engineered wood product that is made out of wood fibers. Types of fiberboard include particle board, medium-density fiberboard, and hardboard. Fiberboard is sometimes used as a synonym for particle board, but particle board usually refers...
  
  
• Hardboard
  Hardboard
  Hardboard, also called high-density fiberboard , not to be confused with 'hardwood', is a type of fiberboard, which is an engineered wood product....
  
  
• Masonite
  Masonite
  Masonite is a type of hardboard invented by William H. Mason.-History:Masonite was invented in 1924 in Laurel, Mississippi, by William H. Mason. Mass production started in 1929. In the 1930s and 1940s Masonite was used for many applications including doors, roofing, walls, desktops, and canoes...
  
  
• Medium-density fiberboard
• Oriented strand board
  Oriented strand board
  Oriented strand board, also known as OSB and SmartPly , is an engineered wood product formed by layering strands of wood in specific orientations. In appearance, it may have a rough and variegated surface with the individual strips Oriented strand board, also known as OSB (UK) and SmartPly (UK &...
  
  
• Particle board
  Particle board
  Particle board, or particleboard , is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extruded...
  
  
• Plywood
  Plywood
  Plywood is a type of manufactured timber made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, re-usable, and can usually be locally manufactured...
  
  
• Pressed wood
  Pressed wood
  Pressed wood is any engineered wood building and furniture construction material made from wood veneers, particles, or wood fibers bonded together with an adhesive under heat and pressure.-See also:*Engineered wood*Fiberboard*Glued laminated timber...
  
  
• Laminated veneer lumber
  Laminated veneer lumber
  Laminated veneer lumber is an engineered wood product that uses multiple layers of thin wood assembled with adhesives. It offers several advantages over typical milled lumber: it is stronger, straighter, and more uniform. It is much less likely than conventional lumber to warp, twist, bow, or...
  
  

External links

• American Institute of Timber Construction
• APA – The Engineered Wood Association
• Glued Laminated Timber Association (UK)
• Glulam 'the naturally engineered solution' from BKTS (UK)
• Glulam Beam Repair/Reinforcement - An article (Printed in STRUCTURE magazine, Sep. 2006) by Gary W. Gray P.E. and Paul C. Gilham P.E.
• Timber Engineering Europe Glulam
• Canadian Wood Council Glulam
• Naturally:wood Engineered Wood
• Rosboro Glulam