Laminated timber

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Contents 1 Material analysis 1.1 Traditional uses 1.2 Emerging uses / trends 1.3 Finish and aesthetic qualities 1.3.1 Finish 1.3.2 Aesthetic Qualities 1.4 Surface forms / shapes 1.5 Cost analysis 2 Material properties 2.1 Primary structural use 2.2 Dimensional and opening restriction 2.2.1 Dimensional Restrictions 2.2.2 Openning Restrictions 2.2.3 Manufacturing process and assembly 3 Environmental impact 3.1 LEED 4 Life Safety & Rating Standards 4.1 Flammability rating 5 References 5.1 Notes 5.2 Student contributions 6 See also 6.1 Similar materials 6.2 Building references 7 External links 7.1 Leading manufacturers

Material analysis

MasterFormat Number: 061800

Traditional uses

• Is used in complete structural systems of large, open spaces
• Stair treads and stringers
• Exterior and Interior Walls, Ceilings, Floors, and Exposed Structures

Emerging uses / trends

• main constitutional element of goods such as furniture, pianos and doors

Finish and aesthetic qualities

Finish

• Timbers can have textured surfaces (such as rough sawn) or they can be stained or painted to match or meet traditional or historic appearance requirements

Aesthetic Qualities

• Surface appearance is divided into four gradations (industrial, framing, architectural, and premium) relative to the aesthetic appearance of the laminated timber.

Surface forms / shapes

• Laminated timber is manufactured in softwoods and hardwoods
• The most popular softwood species are Douglas Fir, Southern Pine and Alaskan Yellow Cedar.

Cost analysis

• Price per Linear Foot: $3 (minimum)

Material properties

Primary structural use

• Compression

Dimensional and opening restriction

Dimensional Restrictions

• Width:
  • Western Species & Hardwoods: 2 ½” to 14 ¼”;
  • Southern Pine: 2 ½” to 10 ½”
• Depth:
  • Western Species & Hardwoods: All depths based on multiples of 1 ½” thick laminations;
  • Southern Pine: All depths based on multiples of 1 3/8” thick laminations;
  • Practical depths are to 72 inches.
• Length:
  • Typically, any length up to 60 feet
  • Custom lengths of up to 175 feet are possible depending on manufacturer

Openning Restrictions

• Horizontal holes:
  • Generally, shall not be greater than 1”; For larger diameters, obtain the advice of a structural engineer or contact the beam manufacturer.
  • Holes should be restricted to the middle third of the span only.
• Vertical holes:
  • Suitability will depend on the size and location of the hole. Seek advice from a structural engineer or the beam manufacturer

Manufacturing process and assembly

Uniform thicknesses of wood spread with waterproof glue are sandwiched together under high pressure in a form matching the desired shape for the member.

Environmental impact

Laminated timber can use fast-growing trees that are responsibly grown and harvested in its manufacture allowing for high efficiency use of timber. The binders used in the lamination process can offgas formaldehyde based on their composition. Some manufacturers are now beginning to use formaldehyde-free binders along with certified wood.

LEED

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Life Safety & Rating Standards

Flammability rating

• Large laminated timbers burn slowly when exposed to a severe fire and do not twist or spall.

References

Notes

• Weyerhaeuser
• Georgia-Pacific Corp

Student contributions

• Seth Novick, Fall 2005
• Neha Sethi, Spring 2008

See also

Similar materials

• Laminate finishes

Building references

• Back Bay T station

External links

Leading manufacturers

• Weyerhaeuser, 200 E. Mallard Drive, P.O. Box 60, Boise, ID 83707, (888) 650-6332

• Georgia-Pacific Corp., 133 Peachtree Street N.E., Atlanta, GA 30303, (800) 225-6119

• Boise Engineered Wood Products, 1111 West Jefferson Street, P.O. Box 50, Boise, ID 83728, (800) 237-4013