Laminated Veneer Lumber (LVL) is a high-strength engineered wood product used primarily for structural applications. It is comparable in strength to solid timber, concrete and steel.
LVL was developed in the 1970s and is today used for permanent structural applications; these include beams, lintels, purlins, truss chords and formwork. This allows LVL to be used wherever sawn timber is used.
Manufacture of LVL
The manufacture of LVL structural timber is created by bonding together rotary peeled or sliced thin wood veneers under heat and pressure. Prior to lamination, the veneers are dried and the grains of each veneer are oriented in the same direction. This makes LVL stronger, straighter and more uniform than solid timber. It also overcomes some of timber’s natural limitations, such as strength-reducing knots which have orthotropic properties; these are different mechanical properties against different axes, in a similar way to the properties of sawn timber. The result is timber with isotropic properties (the same mechanical properties in each direction) in the plane of plywood.
LVL structural timber can support heavier loads and span longer distances than normal timber. LVL can be manufactured to almost any length, restricted only by transportation to site. In addition, the durability of being an engineered wood product means LVL is less prone to shrinking or warping.
Section sizes are cut from 1200 m wide sheets or “billets”. The ability to cut different shapes from the LVL sheets allows for structural innovation using angular and curved shapes.
Properties of LVL
LVL provides a cost-effective and sustainable building material, delivering high structural reliability and strength. Notes that some LVL members are fabricated using a few laminations laid up at right angles to enhance the shear strength of the member. These are known as Cross-Banded LVLs .
LVL is similar to glulam and CLT in that it has high strength, similar to that of hot rolled steel sections. A comparison with steel and concrete shows that structural timber has a strength for weight ratio in excess of 20 per cent higher than structural steel. Also, it is four to five times better than unreinforced concrete in compression.