Glued laminated timber, also

called glulam, is a type of

structural timber product comprising a

number of layers ofdimensioned

timber bonded together with durable,

moisture-resistant structural adhesives. In

North America the material providing the

laminations is termed laminating

stock or lamstock.

By laminating a number of smaller pieces

of timber, a single large, strong, structural

member is manufactured from smaller

pieces. These structural members are

used as vertical columns or

horizontal beams, as well as curved,

arched shapes. Glulam is readily

produced in curved shapes and it is

available in a range of species and

appearance characteristics to meet varied

end-use requirements.[1] Connections are

usually made with bolts or plain steel

dowels and steel plates.

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. [2]:3 As with other engineered

wood products, 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 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.[3] Glulam can be manufactured to a

variety of straight and curved

configurations so it offers architects artistic

freedom without sacrificing structural

requirements.[4] 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.[5] 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.[6]

Contents  [hide] 

1 Glulam versus steel 2 History 3 Sports structures 4 Glulam bridges 5 European Standards Organisation (CEN)

standards 6 See also

7 References 8 External links

§Glulam versus steel[edit]

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.[7]

§History[edit]

Glulam dome roofing the tower of the University of Zurich, built using the Hetzer system in 1911.

Richmond Olympic Oval intern view

One of the earliest still-standing glulam

roof structures is generally

acknowledged[8] to be the assembly room

of King Edward VI College, a school in

Bugle Street, Southampton, England,

dating from 1866, designed by Josiah

George Poole. The building is now the

Marriage Room of Southampton Register

Office.[9]

Two churches in Northumberland are now

thought to have the earliest extant uses:

Holy Trinity, Cambo (1842), and Holy

Trinity, Horsley (1844), and four 1850s

Merseyside churches also feature

laminated timbers: St Mary, Grassendale,

St Luke,Formby, St Paul, Tranmere and

Holy Trinity, Parr Mount, St Helens[citation

needed].

The first industrial patented use was

in Weimar, Germany. Here in 1872[8] 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[8] 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.

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.[2]:4

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.

§Sports structures[edit]

Sports structures are a particularly

suitable application for wide-span glulam

roofs. This is supported by the light weight

of the material, combined with the ability to

furnish long lengths and large cross-

sections. Prefabrication is invariably

employed and the structural engineer

needs to develop clear method statements

for delivery and erection at an early stage

in the design. The PostFinance Arena is

an example of a wide-span sports stadium

roof using glulam arches reaching up to

85 metres. The structure was built

in Berne in 1967, and has subsequently

been refurbished and extended.

The roof of the Richmond Olympic Oval,

built for speed skating events at the 2010

Winter Olympic Games in Vancouver,

British Columbia, features 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.[10]

§Glulam bridges[edit]

Sneek, The Netherlands. Heavy-traffic Accoya Glulam Bridge

Glulam bridge crossingMontmorency River, Quebec.

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 1966–1967.

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.

§European Standards Organisation (CEN) standards[edit]

The following CEN standards are relevant

to the topic of glulam. They are used by all

of the countries that subscribe to the

European Committee for Standardisation:

EN 386  — Glued laminated timber —

Performance requirements and

minimum production requirements

EN 387  — Glued laminated timber —

Large finger joints — Performance

requirements and minimum production

requirements

EN 390  — Glued laminated timber.

Sizes. Permissible deviations

EN 391  — Glued laminated timber -

Delamination tests of glue lines

EN 392  — Glued laminated timber -

Shear test of glue lines

EN 408  — Structural timber and glued

laminated timber — Determination of

some physical and mechanical

properties

EN 1193  — Timber structures —

Structural timber and glued laminated

timber — Determination of shear

strength and mechanical properties

perpendicular to the grain

EN 1194  — Timber structures — Glued

laminated timber — Strength classes

and determination of characteristic

values

EN 14080  — Timber structures — Glued

laminated timber — Requirements

§See also[edit]

Fiberboard

Hardboard

I joist

Masonite

Medium-density fiberboard

Oriented strand board

Particle board

Plywood

Pressed wood

Laminated veneer lumber

Parallam

Timber framing

§References[edit]

1.Jump up^ A Guide To Engineered Wood Products, Form C800 (PDF). APA – The Engineered Wood Association. 2010. p. 7.

2.^ Jump up to:a b Product Guide, Form No. EWS X440 (PDF). APA – The Engineered Wood Association. 2008.

3.Jump up^ Timber Engineering Europe Ltd. Glulam beams

4.Jump up^ Canadian Wood Council Glulam5.Jump up^ Appendix: Mechanics of

Materials, Si Metric EditionFerdinand P.

Beer and E. Russell Johnston Jr.Appendix B Typical Properties of Selected Materials Used in Engineering

6.Jump up^ "About Glulam". American Institute of Timber Construction. Retrieved 3 February 2015.

7.Jump up^ FPInnovations A Synthesis of Research on Wood Products and Greenhouse Gas Impacts page 61

8.^ Jump up to:a b c Müller, Christian (2000). Laminated Timber Construction. Birkhäuser. ISBN 978-3764362676.

9.Jump up^ Leonard, A.G.K. (Spring 2008). "Josiah George Poole (1818–1897): Architect and Surveyor serving Southampton". Journal of the Southampton Local History Forum. Southampton City Council. pp. 19–21. Retrieved 2 June 2012.

10. Jump up^ Naturally:wood Richmond Olympic Oval

§External links[edit]

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

Glulam Romanian

Rosboro Glulam

http://www.wiehag.com/

[hide V T E

Wood products

Lumber/timber

Batten Beam Bressummer Cruck Flitch beam Flooring Joist Lath Molding Panelling Plank Plate Post Purlin Rafter Railroad ties Reclaimed Shingle Siding Sill Stud Timber truss

Treenail Truss Utility pole

Engineeredwood

Glued laminated timber veneer LVL parallel strand I-joist Fiberboard  hardboard Masonite MDF Oriented strand board Particle board Plywood Structural insulated panel Wood-plastic composite  lumber

Fuelwood

Charcoal  biochar Firelog Firewood Pellet fuel Wood fuel

Fibers Cardboard Corrugated fiberboard Paper

Paperboard Pulp Pulpwood Rayon

Derivatives

Birch-tar Cellulose  nano Hemicellulose Cellulosic ethanol Dyes Lignin Lye Methanol Pine tar Pitch Sandalwood oil Tannin Wood gas

By-products

Barkdust Black liquor Ramial chipped wood Sawdust Tall oil Wood flour Wood wool Woodchips

Historical Axe ties

Clapboard Dugout canoe Potash Sawdust brandy Split-rail fence Tanbark Timber framing Wooden masts

See also

Biomass Certified wood Destructive distillation Dry distillation Engineered bamboo Forestry List of woods Mulch Non-timber forest products Papermaking Wood drying Wood preservation Wood processing Woodworking