What is Glulam in Construction?

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Glulam is glued laminated timber formed by stacking a number of timber boards or wood lams and bonding them together using a durable and moisture-resistant adhesive. It is a type of structural engineered wood product that is light in weight with a comparable load-bearing capacity to steel. 

A properly prefabricated glulam possesses excellent resistance to fire and earthquake.

This article discusses the features and benefits of glulam in construction.

Manufacturing of Glulam

The glulam manufacturing process involves producing large structural members from a large number of smaller sawn pieces. The production of glulam is standardized by EN14080 Timber Structures.  

It is composed of wood laminates layered and glued together such that the grain of the laminations runs parallel with the longitudinal axis of the member. Horizontal laminations are most commonly used than vertical laminations as the latter is not suited for curved members.

Laminates are planned before gluing together. The gluing process must be carried out within 48 hours of planning. 

Siberian larch, Douglas fir, spruce, and oak are the tree species that are particularly suited for the laminates used for manufacturing glulam. The thickness of the lamination is determined by the depth of the member to be manufactured. In the case of curved members, the thickness of the laminates is determined by the radius to which the laminate needs to be bent, the species, and the quality of timber.

The manufacturing of glulam is performed within an optimum degree of humidity to minimize contraction and swelling behavior to guarantee dimensional stability of the final material.

Benefits of Glulam

The benefits of glulam are:

1. The manufacturing process of glulam consumes less energy. Hence, it is a material with low embodied energy compared to reinforced concrete and steel.
2. Glulam can be manufactured into various shapes without compromising the structural requirements.
3. They provide high strength and stiffness, enabling them to be used for longer spans, heavier loads, and complex shapes.
4. Glulam possesses a good strength-to-weight ratio compared to steel and concrete, which improves its buildability rate.
5. Glulam provides more design flexibility compared to traditional timber construction. 
6. Glulam designs are preferred over steel or concrete due to their natural appearance.
7. Glulam is a large section of timber element, which chars under fire at a known rate. Hence, it has good fire resistance.

Applications of Glulam in Construction

1. Construction of wide-span glulam roofs for sports structures.
2. Creating bridges and waterfront structures from pressure-treated glulam timbers.
3. Construction of multi-use facilities like churches, libraries, school buildings, etc.
4. For the construction of hurricane-resistant log houses

The world’s tallest glulam structure is Mjøstårnet, which is an 18-story mixed-use building in Norway.

Before using glulam for designing structures, it is necessary to review the local regulations and conditions required by the project. The US standard for glulam construction is given in AITC 115-2009-Standard for Fabricated Structural Glued Laminated Timber Components and Assemblies.

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