Piggyback trusses are what provided by roofing manufacturer when the roof trusses are too tall for delivery, so they have to be capped. Typically, it involves breaking up the trusses into two parts so they can be hauled safely on the road, as the restrictions of local hauling are usually between 12 to 14 inches.
However, before discussing about what are piggyback trusses, it’s best to cover about what a roof truss is in general. A roof trust is a pre-manufactured structure that supports a building’s roof. There are two primary types available, flat and pitched trusses, in which each type can be sorted into more specific types to fit with all kinds of construction projects.
In general, roof trusses in a triangular shape, and it is not without a reason. Triangles are very efficient in allowing limited load control, that’s why they are often found in construction. The roof trusses must support the whole roof weight, so they need to be stable, solid, and strong—characteristics that can be provided by a triangle shape. The strength depends fully on the design.
Most trusses are easy and quick to install without advanced skills required. It is the reason why a large majority of modern houses use trusses. In addition, trusses are able to and also often be used to establish the floor structure too.
Now, let’s move into the piggyback trusses. This specific type of trusses is the small ones that are positioned above the larger trusses in order to make the roof composition attain a certain span or height.
Generally, a piggyback system is extremely time consuming and costly to put together. They can cost anywhere between $800 and $1,500 per building property based on the composition and the amount of removable waste. Trusses, to begin with, are already costly to purchase and install compared to regular lumber. The additional cost it requires is due to the design engineers, delivery, crane, and other resources services needed to build it.
Aside from the expensive cost, another catch of trusses is they can’t be modified on-site. They wholly depend on their design, so any modification attempt including trimming will result in reduced ability to support the roof weight and get through building inspections. Even cutting only half an inch of material will impact its supporting capability. Consequently, it can be concluded that any roof truss, including piggyback trusses, are most beneficial when it can be used without modification and delivered.