Joist vs. Beam — What's the Difference?
By Tayyaba Rehman — Updated on October 7, 2023
Joist is a horizontal member supporting floors or ceilings; Beam is a large horizontal support, often carrying loads of walls, roofs, or floors.
Difference Between Joist and Beam
Table of Contents
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Key Differences
A Joist is a horizontal structural component that provides support for floors or ceilings. It's commonly used in construction to distribute loads across a surface, and you'll typically find joists spaced evenly across the understructure of a floor or ceiling.
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Oct 07, 2023
A Beam, on the other hand, is a more significant horizontal support element in construction. Its primary role is to bear and transfer loads, often from walls, roofs, or even multiple floors, to the structure's columns or foundations.
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While both Joist and Beam play crucial roles in supporting a building, they serve different functions. The Joist is more about distributing weight over an area, ensuring stability for floorboards or ceiling materials. The Beam is about carrying significant loads over longer spans, distributing the weight down to the foundation or other structural elements.
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Comparison Chart
Primary Use
Support for floors or ceilings.
Main horizontal support for structures.
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Size
Typically smaller, even spacing.
Generally larger, spanning long distances.
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Load Bearing
Distributes weight across a surface.
Carries significant loads to columns/foundation.
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Material
Often wood, but can be steel.
Can be wood, steel, reinforced concrete, etc.
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Placement
Found beneath floors and above ceilings.
Found in walls, over doorways, and other spans.
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Definitions
Joist
Structural member distributing floor/ceiling loads.
The sagging was due to a weakened joist.
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Beam
Carries and transfers significant loads.
The beam distributes the roof's weight to the side columns.
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Joist
Can be made of wood, steel, or concrete.
In modern buildings, it's common to see steel joists.
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Beam
Used in roofs, walls, bridges, and more.
The bridge's main beam was constructed of reinforced concrete.
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Joist
Often found evenly spaced.
The joists were spaced two feet apart for optimal support.
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Beam
Spans gaps and can be made of various materials.
The house featured a decorative steel beam in the living room.
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Joist
A horizontal support for floors.
The contractor placed wooden joists across the room's breadth.
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Beam
A long, sturdy piece of squared timber or metal used to support the roof or floor of a building
There are very fine oak beams in the oldest part of the house
The cottage boasts a wealth of exposed beams
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Joist
Connects to beams or bearing walls.
Each joist was anchored securely to the main beam.
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Beam
A ray or shaft of light
A beam of light flashed in front of her
The torch beam dimmed perceptibly
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Joist
A joist is a horizontal structural member used in framing to span an open space, often between beams that subsequently transfer loads to vertical members. When incorporated into a floor framing system, joists serve to provide stiffness to the subfloor sheathing, allowing it to function as a horizontal diaphragm.
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Joist
Any of the wood, steel, or concrete beams set parallel from wall to wall or across or abutting girders to support a floor or ceiling.
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Beam
Transmit (a radio signal or broadcast) in a specified direction
The satellite beamed back radio signals to scientists on Earth
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Joist
A piece of timber or steel laid horizontally, or nearly so, to which the planks of the floor, or the laths or furring strips of a ceiling, are nailed.
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Beam
A squared-off log or a large, oblong piece of timber, metal, or stone used especially as a horizontal support in construction.
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Beam
A transverse structural member of a ship's frame, used to support a deck and to brace the sides against stress.
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Beam
An oscillating lever connected to an engine piston rod and used to transmit power to the crankshaft.
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Beam
The main horizontal bar on a plow to which the share, coulter, and handles are attached.
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Beam
A concentrated stream of particles or a similar propagation of waves
A beam of protons.
A beam of light.
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Beam
To express by means of a radiant smile
He beamed his approval of the new idea.
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Beam
Any large piece of timber or iron long in proportion to its thickness, and prepared for use.
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Beam
One of the principal horizontal structural members, usually of steel, timber, or concrete, of a building; one of the transverse members of a ship's frame on which the decks are laid — supported at the sides by knees in wooden ships and by stringers in steel ones.
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Beam
(nautical) The maximum width of a vessel (note that a vessel with a beam of 15 foot can also be said to be 15 foot abeam).
This ship has more beam than that one.
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Beam
(nautical) The direction across a vessel, perpendicular to fore-and-aft.
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Beam
The crossbar of a mechanical balance, from the ends of which the scales are suspended.
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Beam
(textiles) A cylinder of wood, making part of a loom, on which weavers wind the warp before weaving and the cylinder on which the cloth is rolled, as it is woven.
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Beam
The central bar of a plow, to which the handles and colter are secured, and to the end of which are attached the oxen or horses that draw it.
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Beam
In steam engines, a heavy iron lever having an oscillating motion on a central axis, one end of which is connected with the piston rod from which it receives motion, and the other with the crank of the wheel shaft.
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Beam
A ray or collection of approximately parallel rays emitted from the sun or other luminous body.
A beam of light
A beam of energy
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Beam
(music) A horizontal bar which connects the stems of two or more notes to group them and to indicate metric value.
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Beam
(railway) An elevated rectangular dirt pile used to cheaply build an elevated portion of a railway.
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Beam
(ambitransitive) To emit beams of light; to shine; to radiate.
To beam forth light
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Beam
To transmit matter or information via a high-tech wireless mechanism.
Beam me up, Scotty; there's no intelligent life down here.
The injured crewmembers were immediately beamed to sickbay.
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Beam
To connect (musical notes) with a beam, or thick line, in music notation.
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Beam
Any large piece of timber or iron long in proportion to its thickness, and prepared for use.
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Beam
One of the principal horizontal timbers of a building or ship.
The beams of a vessel are strong pieces of timber stretching across from side to side to support the decks.
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Beam
The width of a vessel; as, one vessel is said to have more beam than another.
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Beam
The bar of a balance, from the ends of which the scales are suspended.
The doubtful beam long nods from side to side.
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Beam
The principal stem or horn of a stag or other deer, which bears the antlers, or branches.
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Beam
A cylinder of wood, making part of a loom, on which weavers wind the warp before weaving; also, the cylinder on which the cloth is rolled, as it is woven; one being called the fore beam, the other the back beam.
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Beam
The main part of a plow, to which the handles and colter are secured, and to the end of which are attached the oxen or horses that draw it.
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Beam
A heavy iron lever having an oscillating motion on a central axis, one end of which is connected with the piston rod from which it receives motion, and the other with the crank of the wheel shaft; - called also working beam or walking beam.
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Beam
A ray or collection of parallel rays emitted from the sun or other luminous body; as, a beam of light, or of heat.
How far that little candle throws his beams!
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Beam
One of the long feathers in the wing of a hawk; - called also beam feather.
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Beam
To send forth; to emit; - followed ordinarily by forth; as, to beam forth light.
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Beam
A signal transmitted along a narrow path; guides pilots in darkness or bad weather
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Beam
Long thick piece of wood or metal or concrete, etc., used in construction
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Beam
Emit light; be bright, as of the sun or a light;
The sun shone bright that day
The fire beamed on their faces
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Beam
Broadcast over the airwaves, as in radio or television;
We cannot air this X-rated song
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Beam
Especially of the complexion: show a strong bright color, such as red or pink;
Her face glowed when she came out of the sauna
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Beam
Experience a feeling of well-being or happiness, as from good health or an intense emotion;
She was beaming with joy
Her face radiated with happiness
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Beam
A primary horizontal support in construction.
The large wooden beam ran across the ceiling, adding character.
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Beam
Often rests on columns, piers, or walls.
The weight of the house rested on beams supported by concrete columns.
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FAQs
What's the ideal material for beams in large buildings?
While it depends on the design and purpose, steel or reinforced concrete beams are common in large structures for strength.
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What's the primary role of a joist in construction?
A joist provides support to floors or ceilings, distributing weight evenly across surfaces.
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How do beams distribute weight?
Beams carry significant loads from structures like walls or roofs and transfer them to columns, piers, or foundations.
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Which is larger, a joist or a beam?
Typically, a beam is larger and designed to carry more significant loads over longer spans compared to a joist.
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Can a joist support walls?
Joists primarily support floors or ceilings. If a wall's weight needs to be supported, beams or bearing walls are typically used.
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Can a beam be vertical?
Generally, beams are horizontal supports, while columns or posts are the vertical counterparts.
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Is every horizontal wood piece in a floor a joist?
Not necessarily. While joists are horizontal supports, there could be other horizontal elements like headers or blocking.
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Are beams always visible in structures?
No, beams can be hidden within walls, floors, or ceilings, but they can also be exposed for aesthetic or design reasons.
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Do joists run perpendicular to beams?
Often, joists run perpendicular to beams to distribute the floor or ceiling load to the beam effectively.
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Can beams be decorative?
Yes, beams can be both structural and decorative, adding character to a space.
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Author Spotlight
Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
