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What Is a Bar Joist?

B. Turner
B. Turner

A bar joist is a structural component used to frame floors or roofs. The bar joist consists of a pair of parallel chords connected by a series of intersecting supports known as "webs." Bar joists feature a similar design to trusses, including the same triangular web pattern, but are generally smaller and more lightweight than most trusses. The design of these joists helps distribute the weight of a floor or roof structure to the walls or foundations at either end of the joist. A bar joist may be made from wood, steel, or composite materials depending on application and loads.

Each bar joist must be carefully selected based on the loads it will support. This includes the weight of building materials, as well as people and furnishings. A structural engineer or architect can help installers select these joists using information such as required span, building design, and local building code requirements.

A bar joist is a structural component used to frame floors or roofs.
A bar joist is a structural component used to frame floors or roofs.

Many manufacturers and industry personnel use an alpha-numeric identification system, such as 12K8, to categorize different types of bar joist. The joist often contains a stamp or label containing this code, which can help buyers and installers identify the joist. The code starts with a number, which represents the depth of the joist in inches. Each depth measurement is followed by a group of letters, which represents the joist design. A "K" indicates a standard joist, while "CS" is used to identify joists designed to support concentrated loads. Other specialty designations are used to identify joists that are very long, deep, or oversized.

At the end of each code is a second number of set of numbers. This figure identifies the type of chords used in each joist. Each particular chord size and thickness corresponds to a matching number, which is constant across different joist materials.

Bar joists offer several advantages over traditional beam or girder construction. Most joist systems are pre-manufactured in factories, and arrive on job sites ready for erection. This helps to speed up the building process and reduce labor costs. A pre-manufactured bar joist is also more precisely constructed than most structures that are framed in the field. This improves building safety and results in a more durable and stable structure. Joist construction also reduces overall waste, which helps reduce disposal and transportation costs.

One of the primary drawbacks to bar joist construction is the high cost of the joist compared to stick framing. While this cost is often offset by labor and disposal savings, stick framing is still cheaper in terms of upfront costs. Because joists must be pre-manufactured to specific design criteria, there is also the risk of time lost to design and engineering.

How Much Do Bar Joists Cost?

Depending on the size and scope of your project, the cost for bar joists may vary. Many manufacturers charge based on the square footage used, so keep this in mind if you consider bar joists. Most bar joists are steel. These usually cost anywhere from $300 to $500 per square foot.

If you have a smaller construction project, like a shed or small building, the prices may be less costly. You may be able to get bar joists for $100 per square foot.

You will also need to think about any shipping fees or fees for customization. It can be $20 or more per square foot or more, so be aware.

Keep in mind that the weight of the materials may be a pricing factor as well. It is especially true when it comes to large projects. If you need heavy-duty supplies, that may increase the price. If you are on a budget or need a different pricing structure, research what manufacturers suit your needs.

Bar Joist VS Truss

While it may seem so, bar joists and trusses are not the same things. However, they are used together in construction, and you need both to build a structure. A bar joist supports the weight of floors and ceilings. A truss is a series of triangles used to support roofs and distribute the weight evenly. Depending on your project, there are different types of trusses available:

  • Floor trusses: This option may be a bit more expensive, but it can impact the quality of your floor. If you have hardwood floors, floor trusses can help ease the strain on the wood and keep it looking great. They can also help with the normal wear and tear of people walking on the floor and causing vibrations. If you are considering hardwood floors or other expensive flooring options, you may want to consider this type of truss.
  • Roof trusses: This option is a structural framework designed to support a roof. You can also use the trusses to bridge the space above a room. Roof trusses are prefabricated and are made in a web of triangles to give the best support.

Both are viable options, but you may want to use one over the other depending on the size of your project. They give excellent strength and span, and the fact that they are prefabricated means their accuracy is better.

On the other hand, bar joists, also known as steel bar joists, come in various sizes and are valuable for different construction projects ranging from small to large.

  • K bar joists: These are useful in projects that have lighter loads. You can use them for roofs as well. If you need a shorter span, this is generally the type you will use.
  • KCS bar joists: If extra loads are going to be present, you will need posts that can withstand constant shear and movement. This type has greater flexibility that allows for this.
  • LH bar joists: These are valuable if you have a heavy load that needs support. Their design is for long-span requirements and heavy loads in unique or complex conditions.
  • DLH bar joists: This type is similar to LH bar joists, but they have various options that allow you to customize them to your needs.

As mentioned, some are better than others. It depends on the weight and size of your roof and structure, so plan accordingly. Bar joists and trusses are not the same things. However, they help support the design you are building in different ways.

Bar Joist Manufacturers

There are many bar joist manufacturers available for your needs. Research to see what companies are nearest to you and have the supplies you need. Many companies have a website so you can see what they offer. A few manufacturers are listed below:

  • New Millennium Building Systems: Established in 1999. Locations in Arkansas, Florida, Indiana, Nevada, Tennessee, and Virginia.
  • Eastern Steel Corp: Established in 1934. Located in Brooklyn, NY.
  • Macuch Steel Products, Inc.: Established in 1948. Located in Augusta, GA.
  • SteelTech Industries, LLC: Established in 2004. Located in Gainesville, GA.
  • Fabricated Steel Products, Inc: Established in 1986. Located in Baton Rouge, LA.
  • Mound Technologies, Inc.: Established in 1964 and located in Springboro, OH.

These are just a few construction material manufacturers in the United States that offer bar joists. They can advise you on which type of joist is best for your project, give you pricing and an estimated cost for your project, and more. If you have questions about choosing construction materials, they may be able to help.

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    • A bar joist is a structural component used to frame floors or roofs.
      By: Greg Pickens
      A bar joist is a structural component used to frame floors or roofs.