Bar Joist Specs

Builders use bar joists, lightweight long-span systems, as support for roofs and flooring.

Standard Bar Joists

Builds use barjoints to support roofs.Builds use barjoints to support roofs.
This component sits in the same position as beams. Bar joists need a bearing surface and extend from girder to girder. Manufacturers produce bar joists for a variety of series. Each type of series has a particular length and loading purpose.

Standard size joists for general application are members of the K series joists, usually open web joists. K series joists have a length ranging from 8 to 60 feet and a depth ranging from 8 to 30 inches. Additionally, this particular series of top and bottom chord section numbers span from 1 to 12. The largest K series bar joist, 30K12, extends from 30 to 60 feet, while the smallest bar joist of this series, 8K1, goes to 16 feet. Examples of K series bar joists include 10K35 and 12K55.

Constant Shear Series

Contractors opt for constant shear series or CS bar joists for concentrated or nonuniformed loads. CS series bar joists run 10 to 30 inches deep, and chord numbers range from 1 to 5. Examples of CS series bar joists are 20CS5 and 30CS1.

Longspan Series

Longspan (LS( series bar joists are similar to K series bar joists. However, LS series bar joists extend from 25 to 96 feet long and range from 18 to 48 inches deep. The top and bottom chord section numbers range from 2 to 17. A few examples of LS series bar joists include 32LH15, 24LH4 and 25 LH2.

Deep Longspan Series

Manufactures denote deep longspan series bar joists as DLH series. This type of bar joist extends from 89 to 144 feet long and has a depth range of 52 to 72 inches. Additionally, the upper and lower chord section numbers span from 10 to 19. Some DLH series bar joists may appear as 55DLH70 and 52DLH12.

Super Longspan Series

The bar joists that fall under the super longspan series are deeper and longer than those in the DLH series. Manufacturers denote this type of bar joist as SLH series. Its length range spans from 111 to 240 feet, and its depth range runs from 80 to 120 inches. In addition, the chord section number runs from 15 to 25. Examples of the SLH series bar joists include 95SLH2 and 105SLH 15.

Bar Joist Code Explanation

When you are reading design plans, you will notice that a three-part code denotes bar joists. For example, the term 12CS2 denotes that the joists is 12 inches deep, it is a part of the CS series bar joists and the chord section number 2 identifies the upper and lower chords.