Joist Vs Beam Vs Girder Whats The Difference

Despite having unique meanings, the terms joist, beam, and girder are usually used interchangeably. Information the adaptation and performance of these key parts is crucial for any engineer, builder, or production worker.

The leading variations between joists, beams, and girders are size, design, and functionality. Joists are usually small but countless and frequently supported by beams. When compared with joists, beams are bigger and fewer. Girders are the largest of the 3 and provide the first horizontal aid to beams.

In this read, we’ll discuss the main differences among joists, beams, and girders. Anyway studying the most changes of the 3 structures, the object will also assess the features and value of every structure.

What Is a Joist in Construction?

Joists are frequently produced from timber, reinforced concrete, or metal and are generally laid in parallel below a roof or floor. In almost all creation projects, joists are laid together in huge numbers to provide enough secondary support.

And to increase their ability to distribute weight around the surface, joists have tiny areas that change depending on the kind of construction. Generally, however, the spacing among joists is generally smaller when compared with spaces in beams.

What Is a Beam in Construction?

A beam is an necessary member that incorporates the main weight of a roof or floor in a building. As the main weight-carriers, beams are extra strong and tremendous compared to joists. A correct beam ought to transfer the burden to the vertical elements, which explains why so much beams in constructions are made out of steel,combined dimensional lumber, or engineered wood.

Below are a few of the leading varieties of beams:

  • Steel beams: Steel beams are more suitable and dearer than wood beams. You’ll find metal beams in large constructions and tall structures. Wood beams are typical in small initiatives along with domestic construction.
  • Combined Dimensional Lumber:Combined beams are more suitable compared to preferred wood beams. This is because combined beams are made while various portions of dimensional lumber are joined to form a stronger, longer beam.
  • Flitch Beams:Flitch beamsare a unique style of beam in that they utilize a metal sheet that’s sandwiched between two units of dimensional lumber. The metallic reinforces the beams, making the structure enhanced and extra able to withstanding weight pressure. The dimensional lumbers that sandwich the steel help to avoid flexing, accordingly keeping the beam in good shape to operate lengthy term.
  • Engineered Beams:Engineered beamsare modified to supply deeper and more suitable load transfer. They are in most cases conventional for his or her I-shaped cross-sections. Engineered beams usually utilize plywood, which allows for personalisation to just about any wanted depth.

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Joists Vs. Beams: What Are the Differences?


Compared to joists, beams are larger in length to enable right load move to the columns and foundation. Beams run horizontally across the ceiling or flooring and play a big position within the structural integrity of a building.

Joists are smaller than beams. The small cross-section location in joists allows for correct weight (and pressure) distribution. When small in size, joists are extremely important in production as a result of their ability to transfer the burden to the beam.


When analyzing ceilings and floors, you’ll observe that joists are usually more in number than other components. Generally, the bigger the construction work, the more the joists necessary for stability. Therefore, in a structure, joists will be more due to their small sizes. Considering that joists have small cross-sections, they’re usually aligned in huge numbers around the load to soak up and transfer the weight to the beam.

Due to their often-large sizes, beams aren’t required in huge portions during construction. This explains why you’ll discover one large beam helping numerous joists in both ceilings or floors. A powerful beam is sufficient to help thousands of joists offered the foundation and columns are in fact constructed.

Point of support

Joists place confidence in beams as their crucial assist in both easy and big creation projects. It’s because joists can both be placed on or beside beams to allow for the appropriate and efficient load transfer.

To help joists and accommodate the load, beams are generally supported by columns. The force of columns and the muse play a big function in identifying the effectiveness of beams in moving loads. By receiving aid from vertical members, beams may be able to accommodate the weight transferred with the aid of joists and distribute it to the columns, where the load is then transferred to the foundation.

What Is a Girder in Construction?

A girder is the main beam that supports different smaller beams, appearing as the primary horizontal aid of a giant structure. Girders have greater load-bearing capability than beams and might for this reason aid extra centred loads.

Due to the ought to provide intense structural assist and cargo transfer, girders are made out of various tough construction substances like stainless steel, concrete, or perhaps a combination of both.

It’s important to notice that each one girders are beams, but no longer all beams could be categorized as girders.

Differences Among Girders and Beams


Beams are imperative parts of a framing procedure in construction projects. Those vital participants are designed to withstand plenty and transfer them to a girder, columns, or foundation.

On any other hand, girders are styles of beams that offer aid to smaller beams, accordingly appearing as a structure’s primary horizontal support. Girders aid the vertical quite a few the beams, ensuring the complete structure is steady and strong enough.


You’ll discover that almost all creation workers refer to large beams as girders. This is because girders are often bigger and more capable of transferring lots when compared with beams. While there is no identical length, width, or weight that determines whilst a beam will become a girder, the largest beam that transfers the weight to the underlying components is generally the girder.

Girders are in most cases utilized in large creation initiatives to supply effective load transfer, that is necessary in retaining the structural integrity of a building or an engineering project.

Contrastingly, beams are mostly used in home creation and other mild creation tasks when you consider that their sizes are sufficiently big to supply the required support.

Load-Bearing Abilities

Due to their strengths and talent to withstand heavy loads, girders are perfect for wearing rolling anddynamic loads, and is the reason why they’re general for bridge construction. And since dynamic plenty exert varying quantities of strain on structures, girders help to supply the essential balance and protection.

While more advantageous than joists, beams aren’t strong sufficient to handle the varying force exerted with the aid of dynamic loads. This explains why beams are perfect for static loads consisting of home ceilings and floors. Therefore, for giant construction projects, girders are wellknown as the first source of horizontal assist when you consider that they’re more suitable and more able to transferring heavy loads.


Basically, girders play the function of imperative beams. They move plenty to columns, which are then transferred to the foundation of the structure. With out a girder, then the danger of bending raises exponentially in huge projects.

Beams perform the function of girders in small projects. A traditional home production project won’t desire a girder when you consider that there won’t be many flooring or constructions exerting additional pressure. But beams operate in a similar manner to girders in that they give structural help with the aid of moving the burden to the columns. Beams are common in residential structures, usually found in walls, floors, ceilings, decks, and roofs.

In a large production project, beams play the role of secondary support. They move the weight to the girder, that’s then disbursed to the columns and afterward transferred to the foundation. Girders are commonly used to hold very heavy loads, which explains their utilization in flyovers and bridges.

Types of Beam Vs. Girder Types

Beams are generally categorised into one of a kind different types depending on the type of assist (fixed, continuous, trussed,cantilever), cross-section form (T-beam, C-beam, and I-beam), and geometry (straight, tapered, or curved).

Girders, more usually than not, refer to strong, metallic beams. I-beam girders are arguably the most typical girders in line with their usage in huge creation tasks consisting of bridges and flyovers.


Fabricating girders calls for the comparison and consideration of factors along with plate sizing, stability, deck placement sequence, flange sizing, welded connections, and erection.

Considering those explanations is vital to the strength and functionality of the girder, and is the reason why girder fabrication is often left to the experts.

Beam fabrication is much less complicated when compared with fabricating girders. The most considerations made when fabricating beams is their potential to move plenty and carry the constitution in place.

Custom metal beam fabrication is a great way to get the specified horizontal help on your construction project. Yet when compared with girders, beam fabrication is simpler and less costly.

FAQs Approximately Joists, Beams, and Girders

What Is a Girder Truss?

Girder trusses have a straight, lengthy design and are characterised with the aid of their vertical and diagonal webs that separate the lowest and correct chords. A girder truss’s primary function is to aid any other ingredients within the body like traditional trusses, purlins, or rafters.

What Structural Member Between a Joist and Beam Is Important?

Both joists and beams are vital to the structural integrity of structures. While beams operate as the primary load-bearing component to a roof or floor, joists are horizontal members that run throughout a structure. Generally, joists require beams to help and distribute the weight to other components along with girders and columns.

Are Beams and Girders Similar?

Beams and girders are similar in that they’re significant participants that provide extra help to different components of the frame. Beams are more normal in domestic production initiatives as a result of their capability to handle small to medium loads.

On the other hand, girders are perfect for commercial initiatives because of their improved load-bearing abilities. A girder is any beam that provides the main horizontal help to a structure. Factor to note, though, now not all beams are girders as some aren’t robust enough to move heavy plenty to other components.

Are Joists Load Bearing?

Not all walls are designed to bear loads. In such walls, you’ll discover that joists tend to run perpendicular to the wall. On load-bearing walls, the joists more often than no longer run parallel to walls, which helps in the transfer of the loads to different members.

What Are Other Normal Constructing Parts?

In addition to joists, beams, and girders, it’s normal to listen to about different important elements that hold up flooring and roofs. Different materials in general outlined in creation initiatives include rafters, trusses, and purlin, which are quickly discussed in the part below.

Rafters: Similar to joists,raftersare countless and are in most cases supported with the aid of beams. When it’s attainable to locate joists in roof and ground structures, rafters are solely found in roofs and never under floors. Rafters have a tendency to sit at an angle and supply additional help to structures.

Purlins:As main parts of ceiling and roof structures,purlinsplay an essential position in proposing additional help to the roofing system. Purlins are usually supported by using constructing walls, rafters, or steel beams before a roofing deck is laid over.

Trusses:Atrussis the name given to a whole assemblage of roof-supporting elements. Trusses may well be assembled on-site, or, for extra elaborate projects, they could be brought in pre-assembled before being set up by using experts on precise of a structure.

The web of joined triangles in trusses assist in weight distribution and allow the roofing manner to handle changing compression and anxiety without shearing or bending, for that reason enabling engineers to accomplish lengthy spans.

Joist Vs. Beam Vs. Girder: Final Takeaway

Although used interchangeably by using some people, joists, beams, and girders have totally one of a kind meanings (and functions) in production engineering.

Of the three imperative elements, joists are the smallest and participate in the function of shifting plenty to beams. And as discussed throughout the article, beams are usually smaller in quantity compared to joists and have a tendency to provide vital help to roofs and floors.

A girder is the strongest of the three members and is usually utilized in large advertisement projects which include bridges and flyovers. The two beams and girders participate in the position of load distribution to different members, but girders are more suitable and boast better load move capabilities.