A 20-foot opening does not tell you what size LVL beam you need. The beam may be carrying a roof, a floor system, a wall above, or some combination of loads, and those conditions can change the required member long before span becomes the deciding factor. An LVL span chart can narrow the choices, but only when you know what the beam is carrying, how that load reaches it, and which manufacturer’s product data applies.
Why There Is No Universal LVL Span Chart
An LVL span chart is a sizing reference that matches specific laminated veneer lumber products and beam configurations to defined spans and loading conditions. Problems start when a chart gets treated as though the span number applies to every LVL with roughly the same dimensions.
It doesn’t.
There is no single maximum span for an LVL beam because allowable span changes with the exact product, member size, loading, support conditions, and deflection limits. Manufacturers publish tables around their own products, design values, applications, and assumptions.
Boise Cascade, for example, publishes separate VERSA-LAM span and size information for its eastern and western U.S. products and also provides BC Calc. Instead of relying on a simple span lookup, the software evaluates the conditions entered for the job against Boise Cascade’s engineered-wood products. You enter the framing geometry and loads, along with details such as holes when they apply, and the program checks the member against Boise Cascade’s product data.
That is very different from starting with, “I have a 20-foot opening,” and picking a beam depth from the first internet chart you find.
The same product-specific approach matters when comparing engineered wood beams such as LVL and glulam. Both can solve structural problems, but the final member still has to be selected from the published information for the product and the actual framing condition.
What You Need Before Opening A Span Table
A clear span is the distance the beam has to bridge between supports. That is where most people start, but it is only one part of the sizing problem.
Before an LVL span chart can give you useful information, you need to know:
- Clear span: The actual distance between bearing points.
- Structural application: Floor beam, header, roof beam, ridge beam, or another condition.
- Tributary width: How much floor or roof area sends load to the beam.
- Live load: People, furniture, stored materials, and other loads associated with the use and occupancy of the building.
- Dead load: The permanent weight of framing, finishes, roofing, flooring, and other fixed materials.
- Roof or snow loads: The applicable roof live load, snow load, or other environmental load used for the project.
- Point loads: Concentrated loads from posts, beams, trusses, or other structural members.
- Beam configuration: The depth, width, and number of plies being considered.
- Bearing conditions: What supports the beam and where those loads go next.
- Exact product: The manufacturer, grade, and LVL product covered by the table.
Leave out one of the major variables and the number in the table may answer a different question from the one your project is asking.
What A Span Table Can And Cannot Tell You
| A Span Table Can Help Determine | A Span Table Cannot Determine By Itself |
| Member options under stated load conditions | Beam size from span alone |
| Allowable spans for the listed product | Whether your project matches the table assumptions |
| Beam depths and ply combinations covered by the table | Whether an unlisted point load is acceptable |
| Limits based on stated deflection criteria | Whether the support below can carry the reaction |
| Requirements included in the manufacturer’s published data | Whether another manufacturer’s product can be substituted |
A table works when the job matches the conditions the table was built around.
Why Two Beams With The Same Span Can Need Different Sizes
Suppose two remodels each call for a beam across a 16-foot opening.
In the first house, the beam supports roof framing over a relatively narrow tributary area. In the second, the same 16-foot beam supports floor joists and a bearing wall above.
The span has not changed. The load has.
Tributary width is one reason that difference can become substantial. It describes the width of floor or roof area feeding load into the beam. As that supported area increases, the beam has to carry more load even though the distance between its supports stays exactly the same.
That gets us to one of the most common questions in this search:
What size LVL do I need for a 20-foot span?
A 20-foot span by itself does not tell you what size LVL you need. You still need the loads, tributary width, beam configuration, bearing conditions, and product-specific sizing data.
One 20-foot opening may be carrying roof framing. Another may be carrying a floor system, another beam, or a bearing wall above. Treating those conditions as interchangeable because the tape measure reads 20 feet is where the trouble starts.
How Beam Depth And Plies Change The Decision
Once the loads are established, beam geometry enters the decision.
Adding another properly connected LVL ply generally increases the built-up beam’s capacity because it increases the member width. That does not mean another ply automatically makes the beam suitable for a longer span or a different loading condition.
Increasing beam depth changes the member differently and can have a substantial effect on how it resists bending and how stiff it is under load. A third ply and a deeper beam are therefore not interchangeable shortcuts.
Multi-ply beams also have to function as an assembly. The plies must be connected so the members transfer loads as the design intends, which is why manufacturers publish fastening and connection requirements for built-up beams.
The same discipline applies to other types of structural composite lumber, including PSL and LSL. Similar-looking engineered members may occupy the same part of a framing plan, but their published design values and allowable applications are not interchangeable.
Changing the member changes what it can carry, but carrying the load is only one performance check.
Strength And Deflection Are Separate Checks
A beam can have enough strength to carry the calculated load and still move too much under that load.
That movement is deflection.
For a floor beam, excessive deflection can contribute to floor movement, noticeable bounce, cracked finishes, and other serviceability problems even though the member has not approached structural failure. Roof and header applications also have limits on how much movement is acceptable.
That is why published tables often account for both strength and deflection rather than asking only whether the beam can carry the load.
Roseburg’s published RigidLam floor-span information, for example, ties its span values to stated live loads, dead loads, member sizes, spacing, and deflection criteria. Change the assumptions and you have changed the problem the table is answering.
So when a member appears to work based on one load value, keep reading. Stiffness or another listed criterion may control the final selection.
How To Read An LVL Span Chart
The safest way to use the table is to start with what the beam carries and follow that load down to the supports.
Identify The Exact Product
Start with the manufacturer and LVL product.
Do not take a span number from one company’s table and assume a different LVL with the same outside dimensions will perform identically. The table is based on the published properties of the product named in it.
Match The Structural Application
A floor beam and a header over a wide opening may have the same clear span while carrying loads in completely different ways.
Start with the table that matches what the member is doing in the building rather than forcing the project into the first chart that contains the span you need.
Confirm The Load Assumptions
Before looking at any span number, read the conditions at the top of the table.
Roseburg’s RigidLam floor-joist span table is a good example of why the heading matters as much as the span number. It is not a beam-sizing table, but it shows how much information sits behind any published span value.
Before using a number from the table, you would first verify that the listed product and loading fit the job. Then check the span condition, spacing, and deflection limit, along with the bearing assumptions used to develop the table.
In this particular example, Roseburg uses 40 psf live load and 12 psf dead load. If those assumptions or the framing conditions differ from the project, the span value is answering a different question.
Find The Span And Member Options
Once the job matches the table assumptions, locate the required span and identify the member sizes or configurations listed for those conditions.
This is where an LVL beam span table starts doing the job most people expected when they began the search. The difference is that you verified the conditions before jumping to a beam size.
Check Deflection And Bearing
Do not stop because one member appears to carry the required load.
Published tables may include separate checks for live load, total load, deflection, and bearing. A member that satisfies one limit can still be controlled by another.
Confirm The Project Still Fits The Table
Now look at the framing again.
A point load from another beam, a cantilever, an unusual support, or a condition outside the stated assumptions can take the job beyond what the quick-reference table was intended to answer.
At that point, stop trying to make the chart fit the job.
Bearing Still Has To Work
Finding a beam that works in the table still does not finish the load path.
There is no single bearing dimension that applies to every LVL installation. Required bearing depends on the beam reaction, the support material, and the published requirements for the product being used.
The loads carried by the beam are transferred into its supports as reaction loads. On a simple-span beam, those reactions occur at the two end supports; multiple-span conditions can also create reactions at intermediate supports.
Those loads then have to move through whatever supports the beam—a post, stud pack, column, wall, or another structural component—and continue down through the building.
That becomes particularly important in remodeling. Removing a bearing wall can produce the open room the homeowner wants while concentrating loads at two relatively small locations at the ends of the new beam.
The beam may be perfectly capable of spanning the opening. That does not automatically mean the existing framing or foundation below those beam ends can carry the concentrated load.
What is underneath the beam matters too.
When A Span Table Or Calculator Is Not Enough
Span tables and sizing programs work well when the framing condition fits the information they were designed to evaluate. Problems start when an unusual condition gets treated like a common one.
Additional analysis may be necessary when a project includes:
- concentrated point loads;
- cantilevers;
- unusual support geometry;
- loads from other beams or columns;
- field holes or notches outside published allowances;
- complex multi-ply connections;
- loads outside the table’s stated range;
- structural substitutions;
- framing that does not match the published application.
There is also an important difference between a generic LVL beam span calculator and a manufacturer’s sizing program.
Some generic calculators use assumed material properties or default design values to estimate a beam. A manufacturer sizing tool evaluates that company’s products using the data assigned to those products. Both still depend on accurate information about the job.
A calculator cannot fix a bad input.
If the framing condition falls outside the published table or the manufacturer’s software cannot model it adequately, the job may require project-specific structural analysis. That could come from the building plans, the engineer of record, manufacturer engineering support, or another qualified design source depending on the project and local requirements.
Use The Manufacturer’s Data For The Beam You Are Buying
Start with the company whose LVL is actually being supplied. Boise Cascade, Weyerhaeuser, Roseburg, and West Fraser all publish product-specific technical information, but they present it in different ways.
Depending on the manufacturer and application, you may be working from span tables, application calculators, sizing software, specifier guides, or user manuals.
The format matters less than making sure the information belongs to the beam you intend to install. Do not collect several manufacturers’ tables and choose the one that gives you the most convenient answer.
Those resources answer the sizing question better than a universal LVL span chart ever could because they connect the span to an actual engineered product, known loads, and stated design assumptions.
The practical sequence is straightforward: determine what the beam carries, establish the span and support conditions, use the correct product data, and verify that the job matches the table. If the condition falls outside it, get the additional analysis before the beam gets ordered.
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