Steel trusses are commonly used in commercial construction. They are pre-manufactured to order and are made in an open web design.
The advantage of using steel trusses for building is that they are stronger than wood, and greater open space inside a building is possible. They are ideal for barns, large storage buildings and commercial construction.
A truss is a structure composed of one or more triangles connected at joints called nodes. The triangle is used because it is the most simple geometric shape which will not distort when the length of the sides are fixed. The joints rare referred to as nodes. Trusses are used in roof structures in order to distribute the weight of the roof evenly on the load bearing walls of the building. The most common use of steel roof trusses is in commercial buildings; more than 20 percent of commercial structures utilize steel roof trusses.
Steel Trusses in Construction
Trusses are used to build more than buildings. Some bridges use a truss design which is clearly visible since the trusses in bridges are usually left uncovered. Steel bridges made with a design that forms triangles are called truss bridges and work on the same principles as roof trusses. These trusses are used to span large spaces or to create tall free standing structures. The Eiffel Tower in Paris is an example of truss construction which demonstrates the strength and durability of the design.
During the past few years, residential builders are starting to use steel roof trusses in the construction of homes.
Advantages of Steel Roof Trusses
The use of steel roof trusses by homebuilders results from the unique characteristics of steel as compared to wood. Steel is lighter than wood thus putting less load and stress on the walls supporting the roof. Steel roof trusses are resistant to both fire and termites, thus there is less maintenance for the homeowner. Steel tends to expand and contract significantly less than wood, meaning there are fewer issues with the structure settling. There is a high level of flexibility in the design utilizing steel roof trusses allowing seamless integration into the existing roof structure in remodeling projects. Prefabricated steel roof trusses are quickly and easily installed, meaning less labor cost for the contractor and homeowner. These advantages contribute to the popularity of steel roof trusses with commercial builders.
Building a Roof with Steel Trusses
As a rule, A steel truss is used in steel frame buildings and are not compatible with wood framing. They are available in a wide variety of roof styles including gable, gambrel, pent and even dome. In general, the specifications for the trusses are sent to the manufacturer and software design programs for steel trusses are available to perform the necessary calculations. It is also possible to design steel trusses using computer assisted truss design software (CAD).
DIY Steel Construction
In most cases the average person does not have the expertise to design steel frame buildings, but a variety of prefabricated small steel building kits are available for sheds, barns and garages. These kits include steel framing and trusses with detailed directions for assembly. Larger structures require that trusses be installed by experienced workers with expertise in steel construction since incorrect installation will impact the structure’s integrity.
Repair and Maintenance of Steel Trusses
As a rule, steel trusses do not require repair or maintenance, but they are subject to rust if exposed to water or moisture. With this in mind, periodic checks for roof leaks and prompt roof repairs should be all that is required for maintenance. Most manufacturers offer a 15 to 20 year warranty on the steel trusses they provide to builders.
Special Equipment for Installation
Like all roof trusses, steel trusses usually require special equipment for handling. Although they are usually lighter in weight than wood trusses, a crane is required to move them into place in large or tall structures. Proper installation of trusses is critical if the trusses are to maintain their strength and bear the forces of tension and compression they are designed to carry. With the exception of small prefabricated buildings, installation of steel trusses requires experts.
Specifications Needed When Ordering a Steel Roof Truss
Contractors and builders order steel roof trusses from manufacturers. The most basic information required is the roof span, and whether or not there is roof or attic mounted heating and air conditioning apparatus. The presence of HVAC equipment affects the stresses put on the roof structure so the design of the truss must consider this factor. The truss manufacturer needs to know whether the attic area will be used as living or storage space and the architectural details planned for the roof. The steel roof truss manufacturer needs to know the location of the structure in order to ensure compliance with local building codes. Additionally, the contractor needs to communicate the number of windows and doors as a proportion to the total wall area. The other information required by the manufacturer of the steel roof trusses includes the wind exposure category, the building category, the span of the roof, the desired pitch of the roof and the building plans.
Environmental Advantages of Steel roof trusses
The use of steel as opposed to wood can be an element of green building practices. Building roof trusses with pre-manufactured steel roof trusses result in significantly less waste as compared to sites built using lumber. The innate resistance of steel to fire and insect damage means the homeowners uses less chemicals such as fire retardants and insecticides, thus there is less toxicity in the air of the home and a decreased chance of these toxins seeping into the water table. The only drawback to steel roof trusses in eco-friendly construction is the amount of energy required to produce the steel.
Steel trusses provide greater strength than wood trusses and allow greater flexibility in building design. They are not commonly used in the construction of single family dwellings, but are used in the construction of multi-family residential structures and commercial buildings. Steel trusses are manufactured to order and are widely used through the construction industry.