What Can You Use King Post Roof Trusses for?

One Post

• A king post truss is named because it has in the center a single vertical brace, called a king post, between two sloping rafter top chords and a horizontal bottom chord. It is the simplest type of truss and uses only four pieces of lumber and four connectors, less than any other style. Like all modern prefabricated trusses, its joints, where two boards meet, are connected with steel gussets, plates which overlap the seam and make a stronger bond.

Long History

• The king post truss style, like many modern roof truss designs, was commonly used in bridge building, although the style originated in the 13th century and was widely used by the 15th century. It was used frequently in churches, barns and bridges and was very common in Britain. It is generally used now for simple roof lines and short bridge spans. A basic king post truss can support no more than 30 feet, depending on the height of the king post, although in houses the limit is usually 16 feet.

Multiple Trusses

• King post trusses can be installed end to end for longer spans; many bridges are made with two king post trusses across an opening. Some king post trusses are reinforced near the peak with horizontal braces called collar ties, and some have "wind braces," angled boards which connect the king post to a peak ridge board.

Barns, Sheds, Garages

• King post trusses were commonly used in ranch style houses built during the boom following World War II. They still are used in some smaller houses but most frequently are used in barns, sheds, garages and carports, and pavilions where a long span is not required. Buildings requiring larger spans often use a variation of the king post called a queen post, which has two diagonal braces, one on each side of the center post, to support the top chords.