About the LVL Span Calculator
Laminated veneer lumber, or LVL, is made by gluing thin sheets of wood veneer together with the grain running the same way. The result is straighter, stronger and more consistent than sawn lumber, so LVL is widely used for beams, headers over wide openings and girders that carry floor joists. It is sold in a standard thickness of 1¾ inches, in depths from about 7¼ to 18 inches or more, and several plies are nailed or bolted together to make a wider beam.
This LVL span calculator gives a first estimate of how far an LVL beam can span. Choose the depth and number of plies, enter the width of floor the beam carries and the loads, and it works out the longest span that passes four checks: bending strength, shear strength, live-load deflection and total-load deflection. It also tells you which check controls and whether your planned span works.
How to Use the LVL Span Calculator
Choose the LVL depth and enter the number of 1¾ in plies.
Enter the tributary width, the width of floor or deck the beam supports.
Enter the live load and dead load in pounds per square foot, and your span.
The Formulas
Step-by-Step Example
load 8 × (40 + 10) = 400 lb/ft, of which 320 is live
section b = 3.5 in, S = 82.3 in³, I = 488.4 in⁴
bending allows about 18 ft 10 in
live sag L/360 allows about 16 ft 6 in
total sag L/240 allows about 17 ft 6 in
shear allows about 39 ft
max span 16 ft 6 in, controlled by live-load deflectionA 14 ft span uses about 85% of that, so it works. A 9¼ in beam of the same width reaches only about 12 ft 10 in, while a 3-ply 14 in beam stretches to about 22 ft 3 in.
Why Deflection Usually Wins
Wood beams are often limited by how much they bend rather than by how much load they can hold before breaking. A floor beam that sags too far cracks plaster and tile, makes doors stick and feels bouncy when people walk across it. Building codes therefore limit live-load deflection on floors to the span divided by 360, and total deflection to the span divided by 240. Because LVL is very strong in bending, these stiffness limits usually control for typical residential spans, and strength controls only on short, heavily loaded beams.
Depth Versus Plies
Understanding Tributary Width
The tributary width is the strip of floor that sends its load to the beam. For a beam under the middle of a house with joists landing on it from both sides, it is half the joist span on one side plus half on the other. For a header over a door in an outside wall, it is half the span of the floor or roof framing that bears on the wall above. Getting this number right matters more than anything else in the calculation, because the load rises in step with it.
What This Calculator Does Not Cover
The calculation assumes a simply supported beam with a uniform load along its length. It does not include point loads, such as a post from the floor above, a girder truss or a bearing wall landing partway along the beam, and these can easily double the bending in part of a beam. It does not check bearing length at the supports, lateral bracing, fire ratings or how the plies are fastened together. Snow and roof loads also need code-specific combinations. Treat the result as a preliminary size for planning and quoting, then confirm the beam with the manufacturer's span tables or sizing software, or with an engineer.
Design Values
LVL makers publish their own allowable values. This calculator uses typical 2.0E grade figures: 2,600 psi bending stress with a size factor for depths other than 12 inches, 285 psi shear and a modulus of elasticity of 2,000,000 psi. Some products are rated higher, and some lower, so small differences from published tables are normal.
Understanding Your Result
The headline is the maximum span in feet and inches.
The beam and load line describes the beam, the load per foot and which check controls.
The your span line says whether your planned span works and how much of the allowance it uses.
The each check line lists the span allowed by each of the four checks.
When Should You Use This Calculator?
Use it when planning to remove a wall and replace it with a beam.
Use it to compare beam options before asking a supplier or engineer to size one.
Use it to understand why a quoted beam is the size it is.
Common Mistakes
Using the whole joist span as the tributary width. Each beam usually carries half.
Ignoring point loads. Posts and walls above need separate analysis.
Mixing brands' tables. Values differ between manufacturers.
Skipping the permit. Removing a bearing wall usually needs approved beam sizing.