Major Types of Timber Truss

Posted on: 6 September 2018


Since the inception of housing, the building and construction industry has come a long way in ensuring the building of quality homes and structures. Although construction varies from grading, plumbing, use of concrete, siding, etc., roofing and framing are a major phase. You cannot build a house from scratch and leave it without a roofing system. It would be outrageous! The process of building a roof is versatile and requires precision of the highest order. Before even installing the roof, the foundation it is built on is made using timber trusses. There are two major techniques used in installing them.

Timber roof trusses

They are structural in nature as they are designed to adequately hold the roof and the ceiling. They are made of several parts that include the top chords (rafters), bottom chords (tie beams) and webs. These type of trusses are divided into two types: closed and open trusses. A closed truss is a truss that has a tie beam and a roof with a ceiling so that the framing system is not visible. The open truss system has a tie beam which is interrupted allowing an open view such that there is no ceiling to hide the view. So, basically, the closed system is made up of three parts. A king post truss with struts, principal rafters, a tie beam and the main king post. Secondly, there is the queen post truss which is made of two queen posts and two principal rafters. The third is a connection of trusses to the king and queen posts.

The open system, on the other hand, is made up of two main parts. First, the arch-based truss consisting of collar beam, arch braces and principal rafters. Secondly, the hammer beam truss which has the collar brace, rafters, beam and braces as the main parts.

Timber wall frames

The traditional way of constructing is by using heavy timber. The timber is carefully fitted with joints and secured by pegs after the joining process is accomplished. This style features foundation and walls where the timber is intersected. The most common designs are box frames, 'cruck' frames and aisled frames. Box frames are made of vertical and horizontal rafters where the load of the roof is carried by the external walls. The cruck frames are two timber frames which are crooked and curved to make a cross frame. Each timber is referred to as a blade. They are several types of cruck including base cruck, raised cruck, middle cruck among others.