The maximum span that a king post truss with 6"x6" Douglas Fir posts can support is 32 feet, assuming a dead load of 20 psf and a snow load of 40 psf. If you increase the snow load to 50 psf, the maximum span decreases to 28 feet. If you want to support a span of 40 feet, you will need to use larger posts.
The king post truss with struts & queen posts is based on the popular king post truss design, but with the addition of two queen posts (pictured above). This timber truss is also very strong, and adaptable with regard to desired span and roof pitch.
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).
King Posts are isolated steel columns that are installed along the line of the proposed retaining wall typically at centres between 1 and 3m.
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.
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' (.
(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.
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 king post truss uses principal rafters, common rafters, purlins, battens, a tie beam, king post, and struts to support roofing materials like mangalore tiles and form a sloped roof at an angle of 1 in 2.
King Post Walls, also known as Soldier Piles, are some of the oldest forms of retaining systems used in deep excavations. They have successfully been used since the late 18th Century in metropolitan cities like New York, Berlin, and London.
The King Post is one of the simplest trusses – it consists of two diagonal members called struts, one horizontal beam that ties the bottom end of the two rafters together, and the vertical king post, which connects the peak to the horizontal beam below.
In king post truss, purlins are supported by the principal rafter. The purlins support the closely spaced common rafters. The slope of common rafters is same as that of the principal rafter. The common rafters support the roof covering.
The number of trusses required for a roof depends completely on the design. However, typical roof truss spacing means that they are usually 400mm (16 inches) or 600mm (24 inches) from centre – this means from the centre of one truss to the centre or the next truss.
King Post trusses are often used in barns and churches, as well as other large buildings. Modern-day designs, however, have started to bring king trusses into smaller structures like sheds, garages and pergolas to create a unique appearance.
The triangle is the strongest to as it holds it shape and has a base which is very strong a also has a strong support. The triangle is common in all sorts of building supports and trusses.
An even more affordable roof truss is the king-post truss. It uses one less lumber compared to the fink truss. It's less sturdy than the fink truss, but it can still hold weight well. A king-post truss has one main post in the center—the king post—and two webbing chords stemming from the bottom.
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.
Characterised by its central vertical post, known as the king post, this truss type effectively supports the weight of the structure's roof or bridge span. Constructed with wood or metal, the king post truss serves as an efficient solution that distributes loads to support wide spans with fewer materials.
What is the optimum angle for a truss bridge? Design engineers normally try to keep it at 45° as it is the best compromise. There are advantages in having a steeper angle for the diagonal members and also disadvantages. Greater depths with lesser number of panels and steeper angles result in lesser chord forces.
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.
These must be followed in order to stay within the purview of the IRC. The limits that apply when snow loads control the design are: Building width not greater than 60 feet perpendicular to the truss span. Truss span not greater than 36 feet.
Queen post trusses are often used in residential and commercial buildings because they are strong and relatively easy to build. The Queen Post Truss is configurable in a range of sizes with typical spans between 16'-40' (4.9-12.2 m) and overall heights of 2'8”-20' (. 81-6.1 m).
Where a King post uses one central supporting post, the Queen post truss uses two. A Queen post truss carries all the load from its rafters and passes it to the vertical posts.
A queen post roof truss is considered the next step in the progression on from king post trusses, in that they are able to span to greater distances.