Do Joists Go On Top Of Beams?

When it comes to any project that carries a lot of weight, a common question is how to best disperse that weight. The answer comes, more often than not, in the form of joists and beams. But in what order are they applied to bear the weight of the project?

Joists go on top of beams to create greater stability for the overall finished project. Joists act as the main support for a load of a house. As such, they themselves need a base to help carry that load. Joists help disperse the load to vertical columns that support the house.

Joists are an important building material that, if installed incorrectly can bring the danger of instability to your project. For ideas for installing joists, and to be more successful with the project that you have chosen, keep reading.

What Types of Projects Will Use Joists?

There are many different types of projects that are completed, with many different functions. But as this article is about joists, here is a list of some common projects that need joists, and in consequence, beams.

  • Floor installations: In any home or building a floor is needed. But underneath the floor, there must be a load-bearing structure. Joists create that support, along with beams to evenly distribute weight.
  • Ceiling/roofs: Joists help support the roof or ceiling of a building as well, and in some cases can be the ceiling and the floor of the next level of the building. These joists may not carry as much weight as floor joists, but they still need to be installed correctly.
  • Pergolas: Many pergolas use joists to help support their structure and create its functionality as shaded areas to sit. Pergolas are not nearly as load-bearing as a home or building but they still create high aesthetic appeal.
  • Porches: All porches have beams and joists for greater support. This allows the porch to both sit out from the house and create a stable walking area for those who wish to be on it.

Beams Vs. Joists

Many people can be confused with the difference between joists and beams. Their purpose may be similar but their placement to fulfill that purpose is different. By understanding what they are needed for, installing them, and using them will come with easier knowledge.

Supporting Columns

First things first, they are both supporting structures that stabilize any project, which is most likely a building. They act to disperse the weight of what they are holding down through the vertical columns.

In many projects, some columns get a project off the ground to meet guidelines either set by the state that you live in or to help keep damage from occurring over time. These columns lead to supporting connectors that can create a box.


But the box is not enough, it needs something more to hold it together. This is where beams come into play. They act as both a horizontal support to keep the columns from tilting sideways, as well as vertical support for whatever goes on top of the overall structure, such as a floor or roof.

The beam goes across and connects to the box structure. This will help disperse the load through the beam, and down the columns to create the stability that you will want.


Unfortunately, beams aren’t quite enough to disperse that load evenly. They need further support and that is where the joists come in. Joists go perpendicular to the beams that are set.

They typically are placed on top of the beam, but they can also go in between. It is more recommended to put them on top due to the greater stability that will come of it.

The weight which sits on the joists disperses down to the beam, which then distributes it into the columns and eventually into the ground in an even manner. This creates the greatest structure stability that is wanted.

Floor Joists Vs. Ceiling Joists

There aren’t too many differences between floor joists and ceiling joists, but there are a couple that could be worth noting.

The main one is the amount of weight that each would be carrying. As the floor joists are supporting the floor, there will always be more weight that they are holding up. This means that floor joists need to be more durable and must be better installed.

Floor joists not only carry the floor but the walls and ceiling as well. So, having the best material and adding more joists work well to help distribute the weight well.

When it comes to ceiling joists, likely, these joists will not be on top of the beam but in between. Also, it will likely be set at an angle for the roof as well.

This will create a different strain on the joists and different installation methods could be used to help with this. These methods could include angled cuts as well as additional boards, and joists upon joists.

Installing Joists

A good Video showing how to install floor joists

So how are joists installed for a project? What is the best way to put them in? Joists as a whole are not too difficult to figure out, they can be installed quite easily.

Depending on how big a project you are completing will help you know the dimension of the lumber board you should use. It is suggested that for smaller projects that are 12 feet or shorter in length you can you a 2×8. For 15 feet use a 2×10, and for longer use 2×12 lumber boards.

After you have your boards you need to measure an equal distance for the joists to sit evenly along the beam. This will give an even balance to the whole structure as a finished project. Make sure to place a mark telling you which side of the line to place the board. Typically they are placed about 16 inches apart.

The next thing to do is measure the length which you need to cut the boards. Simply creating a pencil mark on the joists and then cut them using a circular saw.

After the boards are cut to proper lengths and the measuring is done, then you can start to stand them up and nail them in using a nail gun. Place it at an angle so it goes through the joist and the supporting wood it rests on. This will keep it upright and give greater support to the house later on.

In some cases, the joists will need to be placed in between the beams and the rest of the house. In this case, you will need to use joist hangers.

Installing Joist Hangers

When using joist hangers it is best to cut the joist board to a nice tight fit so the boards can rest where they need. This means that the boards will be placed before the joist hangers are installed.

Joist hangers are supporting metal pieces that stabilize the joist to the beam. The reason you want to put the joist in first and then apply the hangers is to keep the joist from being damaged.

Sometimes if the hangers are added first then the joist needs to be pulled and torqued in weird ways to get it to fit. It can create stress on the board itself and create problems later on including damage and even breakage.

Once the hangers are set to the board you can begin to nail it to the retaining board, and then screw diagonally into the joist so that the screw hits the joist as well as the retaining board, or beam that it is resting against.

Materials For Hangers

Getting a good quality hanger is going to make your project last longer. If you are doing this project by yourself, it is good to seek out and receive recommendations for the best results.

Many professional contractors use the Simpson Strong joist hangers for their durability and functionality. These hangers will last much longer, and they also create the angle to properly screw through the joist itself and into the retaining board.

It is important to have these hangers as tight and flush as possible before screwing them into place. This will give the greatest chance of long use and won’t wear and tear on the board or the hanger.

Also, it is suggested to use 2 1/2 inch nails and screws for the hanger to function the best. This will more than satisfy the guidelines set by the state and will also ensure that your project is pieced together properly.


Joists are the supporting pieces that help take the weight and evenly place it for the base of the home to stay strong. They are placed on top of beams which further support the foundation of the home or other structure and create a necessary balance.

Depending on how you place the beams, there will need to be joist hangers that are added so that the joists are more stable and will hold up their weight better.

The point of the joist is to create a safe floor for people to walk on as well as to help hold a roof over an area without fear of the roof falling in. Joists are important wood supports in the overall project of house building.

Ricky Kesler

With all of the projects I've done over the years, you'd think that I work on my house full-time. But I actually enjoy other things like spending time outdoors and time with my family.

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