An attic truss is a support feature found in many home or building attics. This structure will basically hold up the roof of the home or building and help the roof resist lateral stresses from wind, snow loads, and debris. A home is likely to have a series of attic truss supports running the length of the building — rather than just one — to ensure the load of the roof is adequately spread out and supported. Trusses are usually made from straight wood members, though steel and aluminum trusses are certainly possible as well.
The specific shape and structure of an attic truss can vary. The two most common types are king trusses and queen trusses. These two designs can be used independently or in conjunction with each other. The queen attic truss system is often used to transform an attic space from a simple storage unit into a usable living space by freeing up space in the center of the attic. The general profile of the system will create a large square in the center of the space, and the sides and top of the peaked roof will be supported by straight wooden posts oriented in triangular shapes. This provides strength for the roof while opening up usable living space in the attic.
King trusses are generally used for smaller roofs, or they are used on top of a queen truss. The king attic truss features a central vertical beam around which other support beams will be attached, creating a series of triangles. This design will not generally free up space in the attic, since the center beam will run right into the center of the room. When this is used independently, the attic space is usually used for storage. When it is used in conjunction with a queen truss, the king truss will only run from the peak of the roof to the top horizontal beam of the queen attic truss.
While most truss structures are designed to work in conjunction with peaked roofs, it is also possible to build an attic truss in a gambrel style home or structure. Gambrel roofs are peaked, but the roof will feature two angles of peaking: the lower part of the roof will be peaked at a steeper angle than the upper part of the roof. The truss itself is usually built to coincide with the joint between the two peaks.