Roof trusses are the main form of support in any building with a pitched roof. Oak is uniquely suited to this, as oak trusses have exceptional strength and load bearing capabilities as a natural material. If properly installed, they will last hundreds of years and require virtually no maintenance.
Oak roof materials are surprisingly economical compared to man-made materials and their production has a far lower environmental impact.
In essence, the basic truss design is that of a long based triangle with a tie beam at the base which sits on top of the opposing walls to support the weight of the roof.
What Types of Trusses Are There?
Traditionally, there are three main designs of trusses used: the King, Queen and Collar Truss. Each performs the role of support equally well, but use different styles of weight distribution.
The King Truss is the most traditional design.
It consists of a triangular design but with the addition of a vertical post from the apex to the middle of the tie beam. This is known as the King Post. The tie beam at the base is joined to the base of the rafters to prevent them from spreading apart under the weight of the roof they support. The King Post then transfers the load to the tie beam itself, allowing the beam to bear some of the weight and reducing strain.
Overall strength and support attract many people to the traditional design.
If chosen as a feature truss, additional diagonal braces can be added to either side of the King Post for decorative appearance. Also, the extra braces further increase the strength of the truss itself.
Queen Trusses take the basic triangular design and add two symmetrical posts from the tie beam to the rafters of the truss apex.
These are often joined to the rafters below the point where they support the purlins to transfer the load to the tie beam. This has a similar effect in weight distribution as the King Post but leaves a gap in the middle of the tie beam.
Due to its gap, this Truss creates a ‘tunnel’ effect and can be useful in attic storage. It’s also fantastic for letting natural light flow through the room.
For further strength a collar can also be added to a Queen Truss. This is a smaller horizontal beam that connects the opposing rafters above the joint with the posts.
Collar Trusses, also known as Raised Tie Trusses, as the tie beam is not situated at the base of the rafters but further up.
The main function of the tie beam is to prevent the rafters from spreading. So this design places additional stress on the mortis shoulders where the collar connects to the rafters.
However, if this is taken into consideration and the joints are strengthened accordingly, it should pose no problem. This A – frame truss design is particularly useful for attics or rooms where head space is limited as the collar is further up the rafters.
Half or Mono Trusses
Half, or Mono, Trusses have a similar design to the above types but are one sided. As if the Truss had been halved vertically.
They are mainly used for structures with a lean-to design or extensions with sloped roofs. The half-sized design requires additional braces to reinforce the structure of the roof.
Type of Decorative Trusses
In addition to the truss designs above, there are several more decorative truss styles used for feature trusses.
An Arched Truss shares many design elements with the King and Queen styles. However, the tie beam at the base is a curved or arched rather than straight.
Also known as a Gambrel Truss. This style is used in traditional American barn design. It consists of a wide tie beam, but the rafters have a join two thirds of the way up for an angled roof shape.
A collar then connects the rafters at the join and two King Posts connect the collar ends to the tie beam. A small King Post connects the apex to the collar and several braces reinforce the space between the tie beam and lower rafters. These types of Trusses are a complex design but are rarely seen in British structures.
A Cruck Truss replaces the traditional straight primary rafters with curved ones.
These are connected about two thirds of the way up by a tie beam. Then braced underneath by a short, curved beam and internal brace at either side. However, there are many variations on this type of design. This dramatic design has a gothic, clerical appearance that would be a perfect choice of roof Truss for vaulted ceilings. It can also be fitted below a traditionally angled roof as the curved arch has the strength to support it.
Types of Trusses from Hardwoods Group
Hardwoods Group designs and manufactures any size or style of Oak Trusses.
Contact us today to send us your drawings and we’ll get to work. Quotes can be drawn up in as little as 1 hour and they can be delivered anywhere in the UK in 3 weeks time.