A roof truss is a very strong and stable frame that is made of wood and is held together with the help of metal connector plates. It is a relatively new design that has also been used to provide support and shape to bridges. It is also commonly described as an open web type of design.
Roof truss designs have been considered as a wooden engineering marvel that is highly cost-effective and is well acclaimed in the market as a means to provide low-cost roofing with a high quality that can be used in all commercial and industrial buildings where fire resistance is not a part of the requirement set.
The most common designs are made using ordinary softwood of sizes 2x4" or 2x6", which are held together with the help of joints and a number of wooden and metal fasteners. It is a very delicate piece of structure when it is not in its upright position and can be easily damaged if handled clumsily.
The important points to take care of during the construction of the truss roof include its peak, clear span, pitch, the overall length, and the overhang. Ensure that the lumber is not too moist, is adequately flame-retardant, and the metal connectors used are rust-free.
The design of the roof truss is very complex. The critical nature of the joints makes it difficult to be assembled at the site. Rather, these joints are assembled at a manufacturing plant and are trucked to the final destination. Despite the complex structure and the fact that these structures appear very fragile, these structures are extraordinarily strong once they are erected, mainly due to the amount of sophistication that is put into its engineering.
Roof truss designs are a product of the computer age. Over a hundred years ago, engineers would calculate the amount of stress and build these roofs intuitively, but at that point of time, these designs were an expensive affair that was not feasible for residential or commercial constructions to be built on the budget. The computer has brought a revolution. It's like, you can walk into any of the local lumberyards with a design of the building on your palm and watch the technician key in the specifications and a few seconds later, the printer prints out the design with every piece of lumber identified complete with the joint design and an estimated cost.
The wooden trusses are not just cheap but also offer great strength. This is because they have been engineered in a manner that every piece of wood in the roof structure offers support and strength. To further strengthen the structure, special punched metal plate fasteners were devised. These are used to join pieces of wood together using a hydraulic press.
Because of the complexities involved in building the roof structures with multipronged fasteners with the help of hydraulic equipment, these structures cannot be built at the site of the building. Hence, these roofs are designed at a plant and have to be transported to a location of the building. Transportation itself raises a major drawback. Once the trusses are assembled, they can get a little too big. Sometimes they are too big for a truck. In such cases, specially designed truss trailers have to be used to haul the structures around.
The conventional truss design leaves a large volume of attic space unused as these structures create a web of wood framing that leaves no possible space of using it as a utility. Further, because of the entangled wooden framework, the aesthetic appearance of the roof is very low. No doubt, it can be covered up with wooden trim, but it is an additional cost.
Lastly, these wooden roofs are susceptible to fire. However, an alternative is available these days―the lumber can be replaced with light gauge steel frames, which will not only be more resistant, but more robust when compared to wooden roof trusses.
We hope that this article has provided sufficient information and has shown both the sides of the coin with regards to roof truss designs. However, before you make a final decision, it is imperative that you talk to your contractor or builder to analyze the feasibility and the cost-effectiveness of using a truss roof for your building. Happy building!