Lvl Beam Calculator – Cost Calculator | Online Quote & Profit Estimator

Module Reviewed by: David Chen, PE, Structural Engineer.

Ensuring accuracy in structural capacity and dimensioning based on current building codes and wood engineering principles.

Welcome to the **lvl beam calculator**. This tool helps designers and builders quickly determine the required size (depth or span) for an LVL beam under a uniform load, checking both bending moment and deflection constraints.

LVL Beam Design Calculator

Uniform Load ($w$, PLF):

Beam Width ($b$, inches):

Allowable Bending Stress ($F_b$, PSI):

Modulus of Elasticity ($E$, PSI):

Span Length ($L$, feet) – Leave blank to solve for Max Span:

Beam Depth ($h$, inches) – Leave blank to solve for Required Depth:

Detailed Calculation Steps

LVL Beam Design Formulas

Maximum Bending Moment: $M_{max} = \frac{w L^2}{8}$ (lb-in, $w$ in lb/in, $L$ in inches)

Required Section Modulus: $S_{req} = \frac{M_{max}}{F_b}$ (in³)

Required Moment of Inertia (Deflection Limit $\Delta=L/360$): $I_{req} = \frac{5 w L^3 \times 360}{384 E}$ (in⁴)

Formula Source 1: Engineering Toolbox Formula Source 2: APA – The Engineered Wood Association

Variables Explained

Uniform Load ($w$): The total vertical load applied along the beam’s length, measured in Pounds per Linear Foot (PLF). This includes dead and live loads.
Beam Width ($b$): The thickness of the LVL beam, typically in inches (e.g., 1.75″, 3.5″).
Allowable Bending Stress ($F_b$): The maximum stress the LVL material can withstand in bending, measured in Pounds per Square Inch (PSI). This is a published material property.
Modulus of Elasticity ($E$): The material’s stiffness, indicating its resistance to deflection, measured in PSI. Also a key published material property.
Span Length ($L$): The distance between the beam’s supports, measured in feet.
Beam Depth ($h$): The vertical dimension of the beam, measured in inches (e.g., 9.5″, 11.875″).

What is an LVL Beam?

Laminated Veneer Lumber (LVL) is an engineered wood product created by bonding layers of wood veneers with adhesives under heat and pressure. It is stronger, straighter, and more uniform than equivalent dimensional lumber, making it ideal for headers, beams, and edge-forming material.

Using an LVL beam calculator is essential because LVL strength properties ($F_b$ and $E$) are highly specific and often exceed those of solid-sawn lumber. This allows for smaller beam dimensions for the same load, optimizing material use. The calculator accounts for two primary structural constraints: the stress caused by the bending moment (critical for failure) and the overall stiffness (critical for serviceability and preventing excessive deflection).

How to Calculate LVL Beam Capacity (Example)

Determine Load and Span: Establish the total uniform load ($w$) and the span ($L$). Let’s use $w=400$ PLF and $L=12$ ft.
Select Beam Properties: Choose the material properties, such as $F_b=2600$ PSI and $E=1,800,000$ PSI, and a trial size, say $b=1.75$ in and $h=9.5$ in.
Check Bending Constraint: Calculate the Maximum Moment ($M_{max}$) and the Allowable Moment ($M_{allow} = F_b \cdot S$, where $S = b h^2 / 6$). If $M_{max} > M_{allow}$, the beam fails in bending, and a deeper or wider beam is required.
Check Deflection Constraint: Calculate the Maximum Deflection ($\Delta_{max}$) and compare it to the allowable limit (usually $L/360$ or $L/240$). If $\Delta_{max} > \Delta_{limit}$, the beam is too flexible, and a beam with a higher Moment of Inertia ($I = b h^3 / 12$) or a higher $E$ is needed.
Adjust and Re-calculate: The final design must satisfy both bending and deflection requirements simultaneously.

Frequently Asked Questions (FAQ)

What is the difference between $F_b$ and $E$ in LVL design?: $F_b$ (Bending Stress) governs the strength and potential failure of the beam, ensuring it doesn’t break. $E$ (Modulus of Elasticity) governs the stiffness and deflection, ensuring the beam doesn’t sag excessively under load (serviceability).
Why is LVL generally preferred over standard lumber?: LVL is manufactured to precise, consistent dimensions, eliminating defects found in natural wood. This consistency results in higher strength values ($F_b$ and $E$) and less variance in performance, often leading to smaller, more efficient structural members.
What are typical deflection limits?: Common deflection limits are Span/360 (for interior floor beams, to prevent drywall cracking) and Span/240 (for roof beams). The calculator defaults to the stricter $L/360$ for generic design.
Why do I need to enter the width and depth if I’m solving for one of them?: You must enter the known dimension (e.g., the standard width provided by the manufacturer) to solve for the missing dimension (e.g., the required depth). The cross-section properties ($S$ and $I$) depend on both width ($b$) and depth ($h$).