What size beam do I need for a 25 foot span? determining the size of a beam for a 25-foot span depends on various factors, including the load it needs to support and the type of wood or material used.

Typically, for a rough estimate, you could consider using a 12″×15″ RCC beam, 12-14″ GLULAM or LVL (laminated veneer lumber), W14 steel beam, a triple 2×16 wood beam, or ismb-350 for 2-3 storey residential building applications.

Beam is generally made of concrete providing with reinforcement Steel. It is load bearing structure and flexural member of concrete that vertical transfer all the incoming dead load,live load and self load of rcc slab to the column via column beam joint through development length of structure element.

Size of beam generally depending on span between two support and all the load acting on it. Beam is structural member subjected to flexural stresses and shear forces . The size of the beam (width and depth of beam) are governed by the different type of shear forces and stresses.

When the beam is subjected to loading the bending moment is developed and the moment carrying capacity of the beam depends mainly on the depth of the beam.

How the size of beam could be decided? In case of RCC beams an appropriate width of the beam is assumed on the basis of experience , the magnitude of maximum bending moment and in some cases on the basis of the width of the wall present below the beam. This width of the should be sufficient to provide rebars with sufficient side cover and spacing between the bars. After assuming the width the effective depth of the beam is calculated based on the bending moment and then the overall depth of the beam is determined by adding effective cover to the effective depth calculated.

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**What size beam do I need for a 25 foot span?**

Beam is provided with the top bar which experience compression and bottom bar which experiences tension. Mainly tension bar encounter the bending moment and stirrup of which are provided to incounter the shear forces.

Typically for a 25 foot span, as a rough estimate, you could consider using a 12″×15″ RCC beam, 12-14″ GLULAM or LVL (laminated veneer lumber), W14 steel beam, a triple 2×16 wood beam, or ismb-350 for 2-3 storey residential building applications.

There is various method to deciding beam size its width and depth of beam. 1) IS 456:2000, 2) Thumb rule method

1) According to IS 456:2000 for designing of minimum size of RCC column for 2- 3 storey building its recommendation is:- a) for cantilever beam span to effective depth ratio is 7 (span/effective depth=7), for simply supported beam span to effective depth ratio is 20 (span/effective depth=20) and for continuous beam span to effective depth ratio is 26 ((span/effective depth=26).

**Simply supported beam size for 25 foot span**

For simply supported beam span to effective depth ratio is 20 (span/effective depth=20), given span 25 foot, effective depth =25 ×12″/20=15″, dia of bar=16mm, clear cover of 1″, so overall depth= effective depth+clear cover +1/2dia of bar = 15″+1″+0.3″=16.3″, taking round figure beam depth=18″. Width of beam = D/1.5=18″/1.5=12″, in general it is taken as 12″ inch.

What size beam do i need for a 25 foot span? For 25 foot span, size of simply supported beam for 2-3 storey residential building, using thumb rule, is about 15″×18″ in which beam width is 12″ and beam depth is 15″, if width will be kept 12″, depth should increased, then beam size 12″×24″ can be used, providing with 4nos of 16mm bar at top, 4nos of 20mm bar at bottom and 2nos of 16mm crank bar of Fe500 with stirrup T8@6″C/C and M20 grade of concrete ratio (1:1.5:3) with clear cover 25mm.

**Continuous beam size for 25 foot span**

For continuous beam span to effective depth ratio is 26 (span/effective depth=26), given span 25 foot, effective depth =25 ×12″/26=11.53″, dia of bar=16mm, clear cover of 1″, so overall depth= effective depth+clear cover +1/2dia of bar = 11.53″+1″+0.3″=12.53″, taking round figure beam depth=15″. Width of beam = D/1.5=15″/1.5=10″, in general width of beam is taking as 12 inch.

For 25 foot span, size of continuous beam for 2-3 storey residential building, using thumb rule, is about 12″×15″ in which beam width is 12″ and beam depth is 15″ providing with 2nos of 16mm bar at top, 2nos of 20mm bar at bottom and 2nos of 16mm crank bar of Fe500 with stirrup T8@6″C/C and M20 grade of concrete ratio (1:1.5:3) with clear cover 25mm.

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**What size beam do I need for a 24 foot span?**

2) Thumb rule method:

You can also calculate the size and depth of the beam according to thumb rule method mention below

1 foot (span of the beam) = 1Inch (depth of beam)

If the span of the beam is 25 feet, then the depth of the beam will be 25 inches, beam depth taken as 24″ and beam width 24/1.5=16, taking as 18″.

**What size rcc beam do I need for a 25 foot span?**

Typically for a 25 foot span, the size of rcc beam for 2-3 storey residential building, using thumb rule, is about 12″×15″ in which beam width is 12″ and beam depth is 15″ providing with 4nos of 12mm bar at top, 4nos of 16mm bar at bottom and 2nos of 16mm crank bar of Fe500 with stirrup T8@6″C/C and M20 grade of concrete ratio (1:1.5:3) with clear cover 25mm.

**Steel beam size for a 25 foot span**

Typically for a 25 foot span, the size of steel beam (or universal beam or w beam or I beam or UB’s or hot rolled section) should be ISMB 350 or UB 350×140 (12″×6″) or W14 used for residential building or projects or construction in which depth of section of beam is 350mm (14″) and width of flange or width of beam is 140mm.

**Wood beam size for a 25 foot span**

Typically for a 25 foot span, the size of wood beam need to be triple 2×16 (or 6×16) lumber used for residential building or projects or construction in which depth of section of beam is 400mm (16″) and width of beam is 6″. So, a 3-2×16 size of wood beam is needed to span 25 feet.

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**LVL beam size for a 25 foot span**

Typically for a 25 foot span, you would need atleast 3-1/2″×14″ (or 12 to 14″) size of LVL or Glulam beam for residential application. A 3-1/2″×14″ LVL beam is 14″ in depth and normally 4″ in width. So, a 3-1/2″×14″ size of LVL beam is needed to span 25 feet.

**Conclusions:-**

Typically for a 25 foot span, you would need at least either 12″×15″ RCC beam or 12 to 14″ GLULAM or LVL beam, 3-2×16 wood beam, ISMB 350 or UB 350×140 RSJ, or W14 steel beam.