Wood framing components: the complete guide
Want to build a roof for your home? We recommend you start by having a timber frame built to hold everything up. Discover the different wood roof framing components you’ll need in this article, so you’re ready to nail the job from the get-go!
Our prefabricated wood structure experts discuss the different roof frame components to help you better understand how they are made!
What are the components of a timber roof frame?
A roof frame is an assembly of wood, metal or concrete components that forms the structure of a roof. It is used to support the roof of a building while sculpting it into your desired shape.
Although the purpose of wood frames has remained much the same over time, roof structures have evolved considerably since they were first used in construction. Some components have disappeared while others have been introduced, all with the goal of saving resources and increasing durability.
Rafter
The rafter is one of the components of a roof truss. It consists of a long piece of wood that is inclined and oriented in the direction of the roof slope. It often acts as both a rafter and a crossbeam, which means that it serves both as a support and as a point of attachment for the roof covering.
Roof truss
The roof truss is an assembly of wood parts (rafters, truss strut, scissor truss etc.) that forms a triangle structure. Roof trusses vary in type and size to create different roof shapes. The roof trusses form the structural frame of the roof.
Truss web
The truss web is a straight or rounded piece of wood that is part of the sloped frame (or scissor truss structure). It connects two other pieces of framing together and serves to support and strengthen the structure of the frame. It also stiffens corner connections and helps to hold the parts together.
Purlin Cleat
The purlin cleat is a small piece of wood, attached to the crossbeam. It sustains the perpendicular purlin beam that supports the rafters. Sometimes a cubic cleat is also added between the purlin beam and the purlin cleat.
Purlin
Purlins are pieces of wood that are often placed on the trusses or alternatively directly on the load-bearing wall. They are used to support the rafters and other beams. There are different types of purlin:
- The ridge purlin: found at the top of the frame
- The eaves purlin: found at the end of the sloped scissor trusses
- The middle purlin: found between the ridge purlin and the eaves purlin
Main structural components
The basic elements of a wood frame include the roof truss, the purlins, the purlin cleat, the truss web, and the rafter. However, depending on the structure and strength of the latter, the framework may have other strings to its bow.
Here is what the structural network of your roof’s frame is made up of.
Tie beam
The tie beam is a horizontal piece of wood that maintains the distance between the rafters by preventing the trusses from spreading apart. It is therefore fixed to the lower end of the trusses to generate tension. It is also known as the triangle base.
King post
The king post is a vertical piece of wood that connects the tie beam or straining beam to the top of the roof truss. Note that some types of trusses have only raking shores (see below) and no king post.
Top chord
The top chord is a piece of framing made from metal or wood. It forms the roof slopes. Within a traditional roof frame, the top chord supports the horizontal purlins which themselves support the rafters.
Secondary frame components
Having given you a slight overview of some of the essential elements of a wood roof frame, let’s now take a look at the secondary network components!
Strut
The strut is a piece of wood placed in an angled position between the king post and the rafter. Within a roof truss, its function is to transfer some of the weight supported by the rafter to the king post.
Truss strut
The truss strut is found in some types of roof trusses. It is an inclined piece of wood that provides additional support to the truss.
Anchor posts
These are anchoring interfaces used to secure buildings against falls from heights. They can be installed on metal and wooden frames.
The peak
A frame often has a peak, consisting of two components: the ridge beam and the under ridge.
Ridge beam
The ridge beam connects the trusses to each other under the roof ridge and is the true centrepiece of the roof structure. It is made of a piece of wood placed horizontally on which the rafters are supported.
Under ridge
As its name may suggest, the under ridge is located below the ridge. It is made of a horizontal piece of wood.
Additional timber frame elements
Battens or laths
These parts are usually placed on the rafters so that the roofing materials can be laid on top.
Connectors and fasteners
Although there are various techniques for joining structural components without connectors, most contractors will use some type of connector and fastener to join the various pieces of wood that make up the structure. Among these, metal plate connectors are frequently used in the construction of prefabricated roof trusses.-
Brace
The brace is an assembly of wood parts designed to provide stability to the structure mainly by preventing the trusses from spreading apart under the influence of horizontal forces. The ridge beam, under ridge and purlins are all part of the brace.
Straining beam
The straining beam is very similar to the tie beam described above but shorter in length. It is also placed horizontally between the rafters, but in the upper part of the trusses. A frame can have several straining beams to control downward thrust by resisting compression.
Raking shore
The raking shore is a piece of wood placed at an angle between the king post and the rafter. Its function in a roof truss is to transfer part of the weight supported by the rafter to the king post.
Wall plate
The wall plate is a piece of wood that is placed horizontally at the top of a wall, perpendicular to the trusses. It is used to support the thrust of the trusses.
UsiHome: your timber frame construction experts in Quebec
We hope that this list has helped you learn about the different roof frame components. It doesn’t include every single little detail, but all the essential information is there.
If you have a construction project in the pipelines, UsiHome can provide you with not only structural components such as prefabricated roof trusses, but also floor joists and prefabricated walls. We have everything you need to build a wood frame for your roof.
