Wood is among the oldest of building materials, and remains as one of the most popular used today. Wood beams serve to be some of the most important structural members included in wood framed structures, and are made in a wide variety of sizes and types.
Wood support beams are used and sometimes specifically engineered to serve as structural members. These structural members will most commonly carry loads of roofs or additional floors, but can also carry smaller support beams, thus serving as a girder. Depending on the type that is used, wood beams can and will often be used to fulfil an aesthetic quality as well.
The most commonly used wood beam is glued laminated timber (commonly called "Glulam"), and is engineered in several different sizes for a wide range of load capacities and applications. Dimensional lumber is a more natural looking beam, as it is simply cut to shape from a solid timber; these are commonly used when the beam is to be exposed and finished. Another common type of wood beam is the engineered joist (commonly called "TJI"). This beam type is constructed like a truss system in that it has a central ply-wood webbing capped with small dimensional lumber strips. The TJI is a strong option, and is most commonly used for supporting floor joists.
Structural wood beams are made and available in a seemingly endless range of sizes to fit the demand of just about any load requirement. Smaller beams are used for lighter loads like those over doors and windows and will often be around 4 by 8 inches; larger beams are used for heavier loads from carrying roof rafters to floor joists, and can be as large as 12 by 24 inches in some cases.
Wood has a natural tendency to wear over time, making structural wood beams susceptible to sagging. Depending on the load an location of the beam, this can cause structural problems to the building that can grow to costly repairs. Wood beams are also susceptible to rot and insect damage, so necessary precautions are widely advised.
In most cases, structural wood beams are carrying a substantial amount of weight and mass. When building with these beams, it is important to seek the consultation of a structural engineer and follow specified directives in order to avoid structural failure and the possibility of injury.