About Glulam — Engineered Strength. Unsurpassed Versatility. Dependable Quality.
Glulam is manufactured in both softwood and hardwood species. Popular species include Douglas Fir-Larch, Southern Pine and Alaskan Yellow Cedar. Other species are available upon request. ANSI 117, Design Specifications for Structural Glued Laminated Timber of Softwood Species and AITC 119, Design Specifications for Structural Glued Laminated Timber of Hardwood Species, provides detailed manufacturing and design information.
Glulam: Splendid Arches. Custom Designs. Spectacular Structures.
The natural beauty of wood is unsurpassed. Exposed structural glued laminated timber provides structures with a warmth and beauty unrivaled by other building materials. Glulam members may be textured and finished to meet contemporary, traditional or historic buildings’ appearance requirements.
Long, clear spans and majestic soaring arches are no problem for this versatile structural material. The laminating process used to manufacture glulam enables the creation of any number of straight, tapered and curved shapes. Graceful curved arches and beams are favored for many ecclesiastical designs. The brochure, AITC Structural Glued Laminated Timber in Religious Structures showcases several outstanding religious buildings with laminated timber framing.
Glued laminated timber trusses, beams and arches are used to provide efficient enclosures for expansive areas such as gymnasiums, educational and recreational facilities, indoor pools, auditoriums and shopping centers.
Pressure-treated glulam timbers or timbers manufactured from naturally durable wood species are well suited for creating beautiful and functional 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.
Experience shows that wood is one of the most suitable materials for construction in and around water. Wood is resilient enough to resist battering by the ocean and docking ships, and it is naturally resistant to the destructiveness of salt water. It doesn’t rust or spall; it is not affected by corrosion.
Where wood is fully exposed to weather, or where protection from the elements is insufficient to ensure a moisture content of less than 20% in the glulam, pressure treatment with preservatives is required. Buildings housing wet processes, or where wood is in direct contact with the ground or water, also require preservative pressure treatment. AITC 109, Standard for Preservative Treatment of Structural Glued Laminated Timber provides specific recommendations.
The size of structural glued laminated timber members is limited only by transportation and handling constraints. Widths up to 10-3/4 inches are manufactured using single laminations across the width. Wider sizes are manufactured using two or more laminations across the width of the member. Typical depths range from 5-1/2 inches up to several feet. Standard sizes are described in AITC 113, Standard for Dimensions of Structural Glued Laminated Timber.
The high strength and stiffness of laminated timbers enable glulam beams and arches to span large distances without intermediate columns. This translates to larger rooms and more design flexibility than with traditional timber construction.
AITC’s quality control and inspection system is based on three elements:
- Licensing of manufacturers. AITC licenses qualified laminators whose personnel procedures and facilities have complied with the current edition of ANSI A190.1.
- Quality control. Each licensee agrees to accept responsibility for maintaining a quality control system that is in compliance with the current editions of ANSI A190.1, AITC Standards and AITC Quality Control Systems Manual.
- Periodic plant inspection. AITC’s Inspection Bureau, a nationwide team of qualified inspectors, conducts frequent, unannounced audits and verification of laminators’ in-plant quality control systems, procedures, and production.
For designers and users, AITC brings together all aspects of the engineered timber industry through standards development and technical support activities. AITC standards are recognized by all major building codes in the United States. Standards and technical notes developed by AITC provide guidance to building officials and industry professionals in the design and use of glued laminated timber.
Glulam: Readily Available. Cost Effective. Easily Installed.
Frequently used for spans over 100′ with no intermediate posts or columns, glulam construction is visually and structurally adaptable and generally reduces the overall cost of a project. Individual glulams are easily modified and installed on site – no special crews are required.
The laminating process and use of kiln-dried lumber to manufacture glued laminated timbers minimize wood’s natural propensity to check, twist, warp and shrink in-service. Installations remain dimensionally stable and beautiful over time, virtually eliminating the need for expensive repairs and call backs.
Standard connection details reduce mistakes and allow for rapid installation. AITC 104 Typical Construction Details provides additional guidance for detailing glulam timbers. The availability of long lengths eliminates the need for splices and reduces construction times. Off-site fabrication of custom laminated timbers further reduces installation time.
Renewable Resource, Sustainable Products
Only one primary building material comes from a renewable resource: wood. As it grows, it cleans the air and water and provides habitat, scenic beauty and opportunities for recreation. As a good environmental steward, the forest products industry practices sustainable forestry practices and efficiently uses harvested material. Every log that is harvested under county, state and/or federal forestland management regulations is nearly 100% utilized.
Of the structural building materials, it has the lowest energy requirements for its manufacture, significantly reducing the use of fossil fuels and pollution of our environment compared to other materials. As part of a structure, wood’s natural insulating properties (many times higher than steel or concrete) reduce the energy required to heat and cool the structure for its lifetime. Wood is reusable, easily recycled, and 100% biodegradable, and unlike the resources for other structural materials, the resource for wood volume has been increasing in U.S. net reserves since 1952, with growth exceeding harvest in the U.S. by more than 30%. Just like its parent material, glulam enjoys all of these natural benefits.
In addition to the great environmental benefits associated with wood, glulam timbers extend the available wood resource by using high grade material only where it is needed in the layup. Glulam technology also uses small dimension lumber to make large structural timbers, utilizing logs from second and third growth forests and timber plantations. As a “green” building material, structural glued laminated timber simply can’t be beat.
In contrast, wood retains a significantly higher percentage of its original strength for a longer period of time, losing strength only as material is lost through surface charring. Firefighting is safer due to elimination of concealed spaces and the inherent structural integrity of large glued laminated timbers. Additional information is contained in the brochure, AITC Superior Fire Resistance.
AITC Technical Note 7, Fire Resistance of Exposed Glued Laminated Timbers and AWC Technical Report 10 Calculating the Fire Resistance of Exposed Wood Members provide detailed design methods and layup modifications required for fire-rated glulam construction.