King post trusses are advantageous because they are cost-effective, straightforward to construct, and versatile for different building types. However, their main disadvantage is that they are suitable for shorter spans compared to other truss types due to the limit in structural efficiency over larger distances.
The king post truss is used for simple roof trusses and short-span bridges. It is the simplest form of truss in that it is constructed of the fewest truss members (individual lengths of wood or metal).
Despite their simple structure, Kingpost prefabricated trusses can be used for a variety of purposes. Their suitability to span up to 4 metres makes Kingpost trusses a favourite for use in the construction of small house extensions, garages, garden sheds and dormer windows.
The king post truss is one of the strongest designs and can support very heavy loads. It consists of two vertical posts connected by a horizontal beam at the top. 2. The queen post truss is similar to the king post truss, but it has an additional beam running between the two vertical posts.
The King Post Truss is configurable in a range of sizes with typical spans between 16'-26' (4.9-7.9 m) and overall heights of 2'8”-13' (.
However, their main disadvantage is that they are suitable for shorter spans compared to other truss types due to the limit in structural efficiency over larger distances.
(iii) King Post Truss - Span length is in the range of 5 to 8 meters. (iv) Queen Post Truss - Span length is in between 8 to 12 meters. (v) Pratt Truss - Span length is in between 6 to 10 meters. (vi) Howe Truss - Span length is in between 6 to 30 meters.
Flat Truss: The most basic and affordable option, with spans of up to 6 meters/19 feet. King Post Truss: Simple and cost-effective, with spans of up to 10 meters/32 feet.
Experience has shown us that the weakest part of a wood truss is the connection or panel point. This is where web members and chords meet by, you guessed it, the connection via a metal plate connector.
A Pratt Truss has been used over the past two centuries as an effective truss method. The vertical members are in compression, whilst the diagonal members are in tension. This simplifies and produces a more efficient design since the steel in the diagonal members (in tension) can be reduced.
Quick installation
One of the key benefits of king post walls is their fast installation since they are pre-cast. Aside from being cost-effective, this retaining wall is very versatile. It is the best option for challenging grounds, and they are silent and vibrationless.
When properly constructed with tight-fitting, precisely cut joints, the through-tenon King Post Truss provides a sturdy roof structure. The forces follow a clear load path - down the rafters, into the king post, through the tenon, and into the tie beam.
A king post truss, or turkey track truss, is built with two principal rafters, a tie beam, a central vertical post, and two struts. The central vertical post is what gives the king post truss its triangle shape. For added support, one strut is placed at a 45° angle on each side.
A King Post truss embodies the essence of traditional timber trusses. This type of truss has been used for hundreds of years to support roofs. Featuring a triangular structure formed by a base tie beam and two sloping rafters, the central post adds support from the apex to the tie beam's centre.
The primary difference between the two is that a king post truss has a single supporting post and a queen post truss has two. Applications of each depend on the size of the roof span, with king post trusses spanning 5 to 8 meters. Due to the double posts, queen post trusses have a wider span, measuring 8 to 12 meters.
The vertical king post is used to prevent the sagging of tie beam at the centre of a span. The Struts are connected to the tie beams and the principal rafters in the inclined direction. The Struts are used to prevent the sagging of principal rafters.
Pratt trusses are commonly used in long span buildings ranging from 20 to 100 m in span. In a conventional Pratt truss, diagonal members are in tension for gravity loads. This type of truss is used where gravity loads are predominant (see below left).
Most truss failures are often attributed to one of the following: Improper or lack of temporary/permanent bracing. Incorrect loading or overloading during construction. High winds during erection.
A good thumb rule for the truss spacing is 1/5 to 1/3 of their span. The depth of a truss determines its strength, stiffness, its first cost and the cost of transportation to the site and subsequent erection.
The distance a 2×6 can span is determined by the species, grade, location, use, load, and spacing. Based on building codes, a 2×6 can span anywhere from 2'-1” to 20'-8” depending on the affecting factors. Ceiling joists don't normally have the same load restrictions, and so can span greater distances.”
As one of the biggest and most expensive roof trusses, gable trusses offer a great degree of stability. Comprising multiple vertical trusses, the gable truss acts as an end cap for the roof.
The span across the truss from end to end is about 28', with no bearing wall or support at midspan.
King post truss: Disadvantages
While there are several advantages to using a king post truss, there are also some potential disadvantages that should be considered: Limited span: King post trusses have a relatively limited span, so they may not be suitable for larger buildings or spaces requiring longer spans.
For Example: Calculate the length of the maximum height of the king post in a roof truss to ensure that the slope of the roof is less than 10°. The width of the house will be 40 feet. 40ft tan 8 = opp adj X tan 10° 20 ft 20 ft • tan 10° = x x = 3.52 ft Therefore the king post should be no longer than 3ft 6in.
It is a combination of king-post and queen post trusses. The mansard truss is a two-story truss with the upper portion consisting of a king post truss and a lower portion consisting of a queen post truss.