What is Glulam? Applications and Advantages of Glulam
Glulam, or glue-laminated lumber, is a versatile and innovative construction material used on commercial and residential projects. Glulam is made of single wood layers bonded together with superior wood adhesives. This particular material is available in variable depths and lengths depending on the needs of your construction project and is kind of the perfect building material to be used on long span designs and it is also preferred in curved designs.
Glulam offers great strength and stiffness when compared with dimensional lumber and it is stronger than steel, compared on a pound by pound basis. Connections are usually made with bolts or plain steel dowels and steel plates.
Glulam Common Uses
Glulam members can be used as:
- Straight Beams - Glulam lintels, purling, ridge beams and floor beams
- Columns- Round, square and complex sections.
- Tied Rafters
- Glulam Trusses
- Tied Arches
- Curved Portals
- Domes and Arches
- Arched Bridges
- Curved Beams
Glulam Strength Classification System
Glulam members’ grades are classified using strength properties. Softwood glulam bending combinations have been arranged under a Stress Class System. The first part of the Stress Classification System is the reference bending design value or its flexural loading. For example, a 24F signifies that the member has 2,400 psi of flexural loading, while the second part of this grade classification is the corresponding modulus of elasticity value of the glulam member.
For example, a 24F-1.8E indicates a reference bending design value of 2400 psi and modulus of elasticity of 1.8 x 10^6 psi. Bending combinations glulam members should be used typically as beam and axial combinations should be loaded axially.
Glulam Standard Appearance Grades
Glulam material provides four type of appearance grades as listed in ANSI A190.1 (2002):
Framing appearance grade is the common choice for home building and other areas where glulam is specified combined with dimension lumber. This grade is recommended only in concealed areas.
Industrial grade appearance for glulam material is recommended for areas where the aesthetics are not a major concern. Under this appearance grade, the glulam is finished slightly better than the framing grade, but it is not an aesthetic product. It should be used in areas not visible to general public. This appearance grade will show some wood imperfection on its surfaces, such as knots and voids.
When glulam is going to be used as a facade material or exposed element, Architectural grade appearance is highly recommended. The Architectural appearance grade offers a high-quality finish product, where wooden voids and imperfections are filled or treated to provide a better surface and architectural product.
This grade glulam appearance is only available by special orders and usually used on special occasions, or pre-determined areas, where a high concentration of people is expected. Premium grade glulam offers smoother surfaces that will result in a high-quality finish product.
Why use Glulam?
The material can provide you with the following benefits:
- An all-around product that can be used as roof and floor beams, columns, bracing, decking, and other structural components.
- Green material with very low formaldehyde levels.
- Lightweight material, one-sixth lighter than the same dimension reinforced concrete beam.
- Glulam beams and arches can generate large unsupported span areas.
- Lower transportation and handling costs.
- Material that is easy to repair and install.
- Customizable material to fit your special needs.
- Standard sized available immediately.
- Produced in well-managed forests and certified to PEFC.
- Durable material.
- Great insulation properties.
- Aesthetic material producing eye-appealing finishes.
- It can be manufactured in large section sizes and longer lengths.
- Offers great fire resistant properties and will outlast steel beams under the same fire threatening conditions.
- Glulam members offer precise dimensions, as they are manufactured from seasoned timber.
- CAUTION: Swelling and shrinkage may lead to splitting or delamination of the beam.
Handling and Storage Tips
Glulam members should be handled carefully to avoid any damage or reduction in their structural capacity. It is recommended that:
- Fabric sling should be used when lifting to prevent scratches
- Avoid using chains to lift as this could damage the surface of the glulam.
- Preferably the material should be stored vertically.
- Protect it from the weather by covering with plastic sheeting.
- Keep the material protected until it is ready to be installed unless glulam is intended for exposed areas.