The roof trusses and beams are a basic part of the skeleton of your home or building. They support the roofing material, create a slope for water and snow to shed, and provide space for insulation, ventilation, and other components like heating, cooling, and plumbing. The structural framing that supports these trusses and beams can be affected by many things including wood rot, mold, staining and damage from termites.
Most roof trusses are engineered and manufactured before they are delivered to the construction site. This saves time and money compared to cutting and assembling the same number of individual pieces on-site. It also results in less waste and requires fewer on-site laborers. However, there are some situations when a roof truss must be designed by hand (or by engineer). This is generally due to alterations to the original truss design on-site as well as repair of existing trusses for remodeling projects or other repairs.
Typical rafters are installed on 24-inch centers, and it is common to find a few rafters that don’t align as shown in this photo. This doesn’t necessarily indicate a problem, but it is an indication that the roof framing was not constructed with quality workmanship. Rafters that are not properly aligned may require a purlin system to correct the problem.
Roof trusses can be fabricated in a variety of shapes, sizes and configurations. This includes standard rafters, hipped rafters and angled trusses. Each truss type has its own advantages and disadvantages. For example, a hipped truss is more economical than a standard rafter. However, it may not be as strong as a standard rafter.
Trusses are often fastened roof truss and beam inspections together with plywood gusset plates. If these gusset plates have been cut, this is a sign of a non-professional truss design and should be evaluated by a structural engineer. Also, if a roof truss is showing signs of movement, it should be evaluated by a structural engineer. Truss movement is a result of excess roof loads that exceed the design load of the truss and can lead to failure.
If a roof truss is touching interior walls, this can transfer the load of the roof to walls that are not designed to carry a structural load. This is a serious problem that should be addressed by a qualified structural engineer.