When it comes to constructing the roof of a house people are often confronted with a multitude of choices. One of the most confusing questions to answer is whether you want rafters or trusses. Most people don’t know that there is a difference between the two.

Rafters have many benefits when used in the construction of a roof. Image credit: Wikipedia

Rafters have many benefits when used in the construction of a roof. Image credit: Wikipedia

Rafters are always triangular in shape and are normally made from wood or steel. Usually a rafter will have a singular support beam running the length of the roof span, with its chords (rafters) dispersing the weight of the roof into the structure.

The main difference between rafters and trusses is that rafters are normally installed on site and are normally a part of the structure, and often they are built into the walls. As a large generalisation, however, rafters are usually a heavy gauge of material, like a barn’s roof. According to the experts, rafters also take longer to install and require a specialist. These two requirements make installing rafters expensive, which, in our current economy is a huge factor.

Trusses are a newer technology to rafters, and are more cost-effective. Like rafters, trusses can also be triangular. However, there are more options with trusses, such as large flat expanses of roof (think of warehouse roofs). The major difference between the look of rafters and trusses is that a truss normally has webs providing additional support, whereas rafters do not. A web is a beam of wood between chords.

These webs provide additional support and strength to load bearing capacity. This means trusses are stronger than rafters.

Trusses are normally prefabricated in a factory, under controlled conditions, which means there is a smaller margin for error. The EndoTruss factory based in Elrode, Alberton in Johannesburg, utilises computerised cutting machines that ensure they are millimetre-perfect.

A major bonus is that pre-fabricating a truss makes it easy and quick to install. With a team of installation professionals at hand, it can be done within a day or two.

Normally, trusses are cheaper than rafters on labour costs, as you don’t need to be an artisanal woodworker.