1. LVL AS A CONSTRUCTION MATERIAL Figure 1.2. LVL roof rafters. 1.1 INTRODUCTION Laminated veneer lumber (LVL) is an engineered wood product used in a diverse range of building and bridge construction applications. LVL beams, columns and panels have become established as essential components in modern timber construction due to their numerous advantages, versatility and proven structural performance. This handbook describes the state of the art of LVL from properties and applications to production and design methods. LVL is made of 3 mm thick veneers bonded together with weather-resistant phenolic adhesive. This means that the dimensions of the final LVL product are not limited by the dimensions of the raw material, and even small-diameter logs can be used to produce large LVL beams and panels. When veneer logs are peeled to produce veneer, any natural defects in the wood, such as knots, are dispersed as small fragments across the veneer. This, together with the lamination effect, eliminates the impact of defects and results in exceptionally homogeneous material properties. Although the production costs of LVL, like all engineered wood products, are higher compared to sawn timber, with LVL the same constructions can be designed with smaller dimensions and LVL can also be used for applications where suitable sawn timber sizes are not available. The low deviation of LVL’s high strength and stiffness means that these properties can be fully utilized as characteristic values in structural design. In addition, due to the lack of sizeable defects, the strength to weight ratio of LVL is extremely high – LVL is twice as strong as steel in proportion to weight. Due to its laminated structure, LVL is also dimensionally stable and free of warps, splinters and splits. LVL also comes dry from the factory, eliminating the risk of shrinkage on site or in the ready building, as long as the LVL members are protected against weather exposure. LVL is manufactured to exact dimensions, minimizing cross cutting and sawing waste. The resulting low material waste and uniform quality of LVL improve overall material and time efficiency, especially in industrial applications and off-site production of construction elements. LVL is easy to drill, cut, fasten and fit – only standard wood working tools are needed. LVL components are also highly portable due to their light weight. LVL can also be easily combined with other wood products and construction materials. LVL is produced entirely from traceable, renewable, recyclable wood. It is a natural material from certified sources. LVL also serves as a carbon store in buildings: 1 m3 of LVL contains stored carbon equivalent to 789 kg of CO2, making it an environmentally friendly choice 1, 2, 3. Features and Benefits • Twice as strong as steel in proportion to weight. • Dimensionally stable, no twists, splinters or splits due to laminated structure. • Homogeneous material properties. • Uniform quality and dimensions of the end product; key advantage in industrial applications. • Easy to drill, cut, fasten and fit, only standard wood working tools needed. • Precision-engineered and easily tailored. • Can be produced to exact dimensions, minimizing cross cutting and sawing waste. • Wide range of sizes: product dimensions not limited by raw material size. • Light and highly portable. • Dry from factory, moisture content 8-10% ensured minimal shrinkage in situ. • Easily combined with other construction products. • Off-site production reduces construction time. • Entirely traceable, renewable, recyclable wood from certified sources. • Environmentally friendly carbon store: 1 m3 LVL contains stored carbon equivalent to 789 kg CO2. • Production cost is higher than sawn timber, but less material is needed to meet design specifications when building with LVL 1, 2. Metsä Wood LVL Handbook Europe 9
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