LVL Header Span Table: A Step-by-Step Guide For Beginners

The construction industry increasingly relies on engineered lumber, and understanding the effective use of lvl header span tables is crucial for structural integrity. These tables, often consulted by engineers at organizations like the American Wood Council (AWC), provide critical data for selecting appropriate lumber sizes based on span distances and load requirements. Applying the information found within a lvl header span table, alongside design software simulations, ensures buildings meet safety standards. A key concept in this context is bending moment; the lvl header span table helps determine if a selected lumber can withstand the calculated bending moment for a specific application.

Understanding LVL Header Span Tables: A Beginner's Guide

Laminated Veneer Lumber (LVL) has become a cornerstone of modern construction, providing a level of strength and predictability often unmatched by traditional lumber. As an engineered wood product, LVL offers superior performance in critical structural applications.

One such application is as headers, the horizontal structural members that support loads above openings like windows and doors.

Selecting the correct header size is absolutely critical to ensuring the structural integrity and safety of a building. Too small a header can lead to sagging, cracking, and even structural failure.

The Role of LVL Headers

Headers act as bridges, transferring the weight of the structure above the opening to the supporting walls on either side. They bear a significant load, making the selection of the correct material and size paramount.

Traditional lumber can be used for headers, but LVL's engineered consistency offers greater reliability and allows for longer spans with less material. This is where LVL header span tables come into play.

Introducing LVL Header Span Tables

An LVL header span table is an invaluable resource for builders, designers, and DIY enthusiasts. These tables provide a clear and concise guide for selecting the appropriate LVL size based on the span (the width of the opening) and the load (the weight the header needs to support).

These tables are the key to ensuring structural soundness while optimizing material usage and cost.

Article Objectives

This article aims to demystify the process of using an LVL header span table.

We will provide a beginner-friendly, step-by-step guide that will empower you to confidently select the correct LVL header size for your construction projects.

By the end of this guide, you'll understand how to read, interpret, and apply the information contained within these tables.

and Headers: The Foundational Concepts

Before diving into the specifics of LVL header span tables, it's crucial to establish a solid understanding of the fundamental concepts underpinning their use. This section will explore the nature of LVL, the function of headers within a structure, and the critical importance of accurate load calculations.

What is LVL (Laminated Veneer Lumber)?

LVL, or Laminated Veneer Lumber, is a high-strength engineered wood product used extensively in construction. Unlike traditional lumber sawn directly from a tree, LVL is manufactured through a carefully controlled process.

This process involves bonding thin wood veneers together under heat and pressure, using durable adhesives. These veneers are arranged with the grain running parallel, maximizing the material's strength along its length.

Advantages of LVL Over Traditional Lumber

LVL offers several significant advantages over traditional lumber. These include:

• Superior Strength: The layered construction and parallel grain alignment result in a higher strength-to-weight ratio than typical lumber.

• Consistency: The manufacturing process allows for strict quality control, resulting in consistent material properties and predictable performance. This consistency minimizes the risk of defects or weak spots found in natural lumber.

• Dimensional Stability: LVL is less prone to warping, twisting, and shrinking compared to solid lumber. This stability ensures that structural elements remain aligned and perform as intended over time.

Beyond Headers: Other Applications of LVL

While this article focuses on LVL headers, the material finds application in a variety of structural components, including:

• Beams: Supporting loads over long spans.

• Rim Boards: Providing edge support for floor systems.

• Columns: Providing vertical support in post-and-beam construction.

Defining Header and Span

Understanding the role of a header and the concept of span is essential for correctly utilizing LVL header span tables.

The Function of a Header

A header is a horizontal structural member used to support the load above an opening in a wall, such as a window or door. The header essentially acts as a bridge, transferring the weight of the structure above the opening to the supporting wall studs on either side. Without a properly sized header, the weight above the opening would cause the framing to sag or collapse.

Understanding Span

The span is the horizontal distance that the header needs to cover – the clear opening between the supporting walls or posts. The span directly impacts the load the header must bear. A longer span requires a stronger header to adequately support the weight above.

Visualizing the Relationship

Imagine a doorway in a wall. The header runs horizontally above the door frame. The span is the width of the doorway itself. The header’s job is to carry the weight of the wall and roof above the doorway, transferring it to the vertical studs on either side of the door opening.

(Include a diagram here showing a header spanning an opening, labeled with "Header," "Span," and "Supporting Studs.")

Importance of Load Calculations

Selecting the correct LVL header hinges on accurately determining the loads it must withstand. Underestimating the load can lead to structural failure, while overestimating it can result in unnecessary cost and material usage.

Types of Loads

Headers are subjected to two primary types of loads:

• Dead Load: This is the weight of the structure itself, including the wall framing, sheathing, roofing materials, and any permanent fixtures.

• Live Load: This encompasses variable loads such as occupancy (people, furniture), snow accumulation, and wind pressure. Live loads can fluctuate, so building codes typically specify minimum values to account for potential maximums.

The Role of Professionals

Accurate load calculations can be complex, particularly in situations involving unusual roof designs, heavy snow loads, or large open spaces.

In such cases, it is highly recommended to consult with a qualified structural engineer or architect. These professionals possess the expertise to analyze the specific conditions and determine the precise loads that the header must bear, ensuring the structural integrity and safety of the building.

Unlocking the LVL Header Span Table

LVL header span tables are essential tools for selecting the correct LVL size for a given application. These tables provide pre-calculated values that simplify the selection process, ensuring structural integrity and compliance with building codes. However, understanding how to find and interpret these tables is crucial for their effective use.

Locating the Table

The first step is to find a reliable LVL header span table. These tables are not generic; they are specific to the LVL product being used.

Common sources include:

• Manufacturer's Websites: Companies like Boise Cascade, Weyerhaeuser, and Roseburg offer downloadable tables for their LVL products. These are usually found in the "Technical Resources" or "Product Literature" sections of their websites.

• Engineering Handbooks: Structural engineering handbooks often contain LVL span tables, though these may be limited in scope.

• Online Resources: While online searches can yield results, exercise caution and verify the source of the table. Ensure it comes from a reputable manufacturer or engineering organization.

• Why Product-Specific Tables Matter: LVL products vary in their material properties (grade, species, adhesive type), directly influencing their load-carrying capacity. Using the wrong table can lead to significant errors in header selection, compromising structural safety.

Understanding the Columns and Rows

Once you've located the appropriate table, the next step is understanding its structure. LVL header span tables are organized in a matrix format, with columns representing key parameters and rows presenting different combinations of those parameters.

Column Definitions

Here's a breakdown of the common columns found in LVL header span tables:

• Span: This column indicates the maximum allowable span that the LVL header can cover, typically expressed in feet and inches. This is the horizontal distance between the header's support points.

• Load: This column specifies the maximum load the header can support over the given span. This is usually expressed in pounds per linear foot (PLF). It's critical to ensure that the calculated load on the header does not exceed the value listed in the table.

• LVL Size: This column provides the dimensions of the LVL header required. This will be expressed as width x depth (e.g., 3.5" x 9.5"). The width represents the header's thickness, while the depth indicates its height.

• Number of Plies: This column specifies the number of individual LVL pieces that must be combined to achieve the required strength. Headers can be constructed from a single LVL piece (single-ply) or multiple pieces fastened together (multi-ply).

Row Interpretation

Each row in the table represents a unique combination of span, load, LVL size, and number of plies. By finding the row that corresponds to your calculated span and load, you can identify the appropriate LVL header size for your application.

Interpreting Footnotes and Caveats

LVL header span tables are not simply a collection of numbers. They are accompanied by footnotes and caveats that provide critical information about the table's assumptions and limitations. Ignoring these notes can lead to serious errors.

Common Caveats

Some common caveats found in LVL header span tables include:

• Allowable Deflection Limits: This specifies the maximum amount the header is allowed to deflect under load. Deflection limits are often expressed as a fraction of the span (e.g., L/360), which restricts the amount of bending allowed.

• Specific Gravity Requirements: Some tables specify minimum specific gravity requirements for the framing lumber used to support the header.

• Connection Details: The table may reference specific connection details, such as the type and spacing of fasteners required to connect the LVL plies or to attach the header to the supporting structure.

• Load Duration Factors: Many tables use Load Duration Factors that account for the nature of the load. A permanent dead load requires a different factor than short duration snow or wind load.

Adherence to Building Codes

Perhaps the most crucial caveat is the requirement to comply with local building codes. LVL header span tables are based on engineering principles, but local codes may impose additional restrictions or requirements. Always consult with your local building department or a qualified professional to ensure that your header selection meets all applicable regulations.

Step-by-Step: Using the LVL Header Span Table

Now that we understand the anatomy of an LVL header span table – where to find them and how they are organized – let's put that knowledge into practice. The following section presents a detailed, step-by-step guide to effectively using these tables for selecting the appropriate LVL header.

Step 1: Determine the Span

The first, and arguably most crucial, step is accurately determining the span that your header needs to cover. This is the clear distance between the inside faces of the supporting walls or columns.

Measuring the Opening

Use a measuring tape to precisely measure the width of the opening where the header will be installed (e.g., door or window opening). This measurement is the starting point, but it’s not the final span value.

Accounting for Bearing Width

The header doesn't just sit on top of the opening; it needs adequate bearing – that is, it needs to extend a certain distance onto the supporting walls on either side. This bearing provides stability and transfers the load effectively.

Consult your local building codes or the LVL manufacturer's specifications for the required minimum bearing length. Common values range from 1.5 inches to 3 inches on each side, but always verify the specific requirements for your situation.

Add the bearing width from both sides to the opening measurement.

For example, if your opening is 6 feet (72 inches) wide and the required bearing is 2 inches on each side, the total span would be: 72 inches + 2 inches + 2 inches = 76 inches, or 6 feet 4 inches.

This final span measurement is what you'll use to consult the LVL header span table.

Step 2: Calculate the Load

Determining the load that the header will bear is a critical step that often requires a degree of expertise. The load is the total weight that the header must support, including the weight of the structure above it.

This section provides a general overview, but complex load calculations should always be performed or reviewed by a qualified structural engineer or architect.

Understanding Dead Load and Live Load

The total load is comprised of two primary components: dead load and live load.

• Dead Load: This refers to the weight of the permanent structural elements supported by the header. This includes the weight of the wall itself (framing, sheathing, siding), any flooring, roofing, or other permanent materials directly above the header. Estimating dead load involves calculating the weight of each material based on its density and volume.

• Live Load: This represents the variable, non-permanent loads on the structure. This includes occupancy loads (people, furniture), snow load on the roof, wind load, and any other temporary forces acting on the structure. Live load requirements are typically dictated by local building codes and depend on the building's use and location.

Simplified Load Calculation Example

For a simplified example, imagine a header supporting a section of wall that is 8 feet high.

Let's assume the wall's dead load is 20 pounds per square foot (psf) and the roof's live load (snow load) is 30 psf. If the header spans 6 feet and supports half of the 8-foot wall height (4 feet) plus the roof load, the total load calculation would be:

• Wall Dead Load: 20 psf

  **4 feet = 80 pounds per linear foot (PLF)

• Roof Live Load: 30 psf** 6 foot tributary width (assuming roof load transfers evenly) = 180 PLF
• Total Load = 80 PLF + 180 PLF = 260 PLF

Therefore, the header needs to support 260 pounds per linear foot. This calculation is a gross simplification and serves only as an illustration. Actual load calculations can be significantly more complex, particularly for multi-story buildings or unusual structural designs.

The Importance of Professional Consultation

It is essential to emphasize that accurate load calculations are paramount to structural safety. If you are unsure about any aspect of load calculation, consult with a structural engineer or architect. They have the expertise to accurately assess the loads and ensure the header is adequately sized.

Step 3: Consult the Table

With the span and load calculated, it's time to consult the LVL header span table. Remember to use the table specific to the LVL product you intend to use.

Locating the Correct Row

Look for the row in the table that matches your calculated span and load requirements. The table may not have an exact match for your specific values, so you'll need to make a judgment call.

Generally, it's safer to round up to the next higher span value or load value. For example, if your span is 74 inches, but the table only lists values for 72 inches and 78 inches, use the 78-inch value. Similarly, if your calculated load is 270 PLF, but the table only lists 250 PLF and 300 PLF, use the 300 PLF value.

Identifying the Required LVL Size and Number of Plies

Once you've located the appropriate row, identify the corresponding LVL size and number of plies. The LVL size will be expressed in terms of its thickness and depth (e.g., 1.75" x 9.5"), and the number of plies indicates how many individual LVL pieces need to be fastened together to achieve the required strength.

For example, the table might specify a 3.5" x 11.875" LVL header consisting of two 1.75" plies. This means you'll need to install two pieces of LVL that are each 1.75 inches thick and 11.875 inches deep, fastened together according to the manufacturer's specifications.

Step 4: Verify Building Code Compliance

Selecting the appropriate LVL header isn't just about matching span and load requirements; it's also about ensuring compliance with local building codes.

Building codes are regulations that govern the design and construction of buildings to ensure public safety. These codes often specify minimum requirements for structural members, including headers.

Finding Local Building Codes

• Local Building Department: Your local city or county building department is the primary source for building code information. They can provide copies of the relevant codes and answer questions about specific requirements.
• Online Resources: Many local governments also publish their building codes online. Search your city or county's website for "building codes" or "construction regulations."
• International Building Code (IBC): The IBC is a widely adopted model building code that serves as the basis for many local codes. While your local code may have amendments or variations, the IBC can provide a general understanding of common requirements.

Checking for Specific Requirements

Review the building codes to ensure that the selected LVL header meets all applicable requirements. This may include:

• Minimum size and number of plies: The code may specify minimum dimensions for headers based on span and load.
• Species and grade of lumber: The code may restrict the use of certain species or grades of lumber for structural applications.
• Connection details: The code may specify how the header must be connected to the supporting walls or columns.
• Deflection limits: The code may limit the amount of deflection (bending) that the header can experience under load.

If the selected LVL header does not meet all applicable building code requirements, you'll need to choose a larger size or consult with a structural engineer to explore alternative solutions.

Ignoring building codes can have serious consequences, including structural failure, safety hazards, and legal penalties. Always prioritize building code compliance when selecting an LVL header.

Practical Application: An Example Scenario

To solidify our understanding, let's walk through a practical example of how to use an LVL header span table. Imagine we're framing a new opening for a large picture window in a residential home.

Scenario Setup: The Picture Window Project

Let's assume the desired opening width is 8 feet (96 inches). After consulting local building codes and the LVL manufacturer's specifications, we determine that a minimum bearing length of 2.5 inches is required on each side of the opening.

Therefore, the total span is calculated as follows:

96 inches (opening width) + 2.5 inches (bearing side 1) + 2.5 inches (bearing side 2) = 101 inches, which is approximately 8.4 feet.

Calculating the Load: Dead Load and Live Load

Next, we need to determine the total load the header will need to support. This involves calculating both the dead load (the weight of the structure itself) and the live load (variable loads such as snow, occupancy, or wind).

For simplicity, let's assume a structural engineer has provided us with a total load calculation of 350 pounds per linear foot (PLF). This figure accounts for the weight of the wall above the opening, including framing, sheathing, and siding, as well as a portion of the roof load transferred to the wall.

It's crucial to emphasize that accurate load calculations are paramount to ensure structural integrity. When in doubt, always consult a qualified structural engineer.

Consulting the LVL Header Span Table: Finding the Right Fit

Now, we consult the LVL header span table for the specific LVL product we intend to use. For this example, let's assume we are using a table from Boise Cascade for their VERSA-LAM® LVL.

We look for a row in the table that accommodates a span of at least 8.4 feet (or slightly greater, for safety) and a load of at least 350 PLF.

Hypothetically, let's say the table shows the following entry:

• Span: 8.5 feet
• Load (PLF): 375
• LVL Size: 3.5" x 11.875"
• Number of Plies: 2

This indicates that a header made of two plies of 3.5" x 11.875" VERSA-LAM® LVL can safely support a load of 375 PLF over a span of 8.5 feet.

Since our calculated load (350 PLF) is less than the table's allowable load (375 PLF), this LVL size appears to be adequate.

Verifying Building Code Compliance: The Final Check

However, our work isn't done yet! It is absolutely essential to verify that this selection meets all applicable local building codes.

Building codes may have specific requirements regarding allowable deflection, connection details, or other factors that are not explicitly covered in the LVL header span table.

Consult your local building department or a qualified inspector to confirm that the selected LVL header meets all relevant regulations before proceeding with construction.

Ignoring this step can have serious consequences.

This example illustrates the importance of carefully following each step in the process: accurately determining the span, calculating the load, consulting the LVL header span table, and, critically, verifying compliance with building codes. Only by adhering to these steps can we ensure a safe and structurally sound installation.

Now, with a practical understanding under our belts, it's time to turn our attention to the potential pitfalls that can arise when working with LVL header span tables. Awareness of these common mistakes is crucial to ensuring a safe and structurally sound outcome.

Avoiding Pitfalls: Common Mistakes to Watch Out For

Using LVL header span tables effectively requires a keen eye for detail and a thorough understanding of the underlying principles. Overlooking crucial aspects can lead to significant structural problems, safety hazards, and costly rework. Let's explore some of the most common mistakes and how to avoid them.

Selecting the Incorrect LVL Header Span Table

One of the most frequent errors is using the wrong LVL header span table. Remember, each manufacturer and even specific LVL product lines within a manufacturer will have unique span tables.

These tables are developed based on specific material properties, manufacturing processes, and testing data. Using a table intended for a different LVL product will result in inaccurate size selection and potentially compromise the header's load-bearing capacity.

Always verify that the table corresponds to the exact LVL product you intend to use. Double-check the manufacturer's name, product series, and any other identifying information printed on the table itself. Download tables directly from the manufacturer's website to guarantee authenticity and the latest revision.

The Peril of Inaccurate Load Calculations

Even with the correct table, inaccurate load calculations can render the selection process useless. Load calculations are the foundation upon which the entire header sizing process rests. Underestimating the load can lead to header failure, while overestimating can result in unnecessary expense and material waste.

It's essential to accurately determine both the dead load (weight of the structure) and the live load (variable loads like snow or occupants). This often requires a detailed understanding of building materials, structural design principles, and local building codes.

For complex structural situations or when dealing with unfamiliar construction techniques, always consult with a qualified structural engineer or architect. They possess the expertise to accurately assess the loads and provide appropriate recommendations.

Ignoring Footnotes and Caveats: A Recipe for Disaster

LVL header span tables are often accompanied by footnotes and caveats that outline specific limitations, conditions, and requirements. These notes are not merely suggestions; they are integral to the proper application of the table.

Common caveats might include restrictions on allowable deflection, requirements for specific connection details, or limitations based on the wood's specific gravity. Ignoring these stipulations can lead to substandard performance or even structural failure.

Carefully read and understand all footnotes and caveats before making any header selection. Failure to do so is akin to driving a car without reading the owner's manual – you might get away with it for a while, but eventually, something will go wrong.

Building Code Blindness

Building codes are in place to ensure the safety and well-being of occupants and the structural integrity of buildings. Failing to adhere to local building codes when selecting an LVL header is not only illegal but also potentially dangerous.

Building codes often specify minimum header sizes, allowable spans, and required connection details. They may also impose additional requirements based on factors such as seismic activity or wind exposure.

Before commencing any header selection, familiarize yourself with the relevant building codes applicable to your project. Contact your local building department or consult with a qualified building inspector to ensure full compliance.

Installation Imperfections: The Final Blow

Even with a perfectly sized header selected according to the correct span table and building codes, improper installation can negate all the preceding efforts. Proper bearing, secure connections, and correct alignment are crucial for ensuring the header performs as intended.

Insufficient bearing can cause the header to crush or deflect excessively. Inadequate connections can lead to premature failure under load. And misalignment can introduce stress concentrations that weaken the structure.

Always follow the manufacturer's installation instructions and best practices for construction. If you lack the necessary experience or expertise, hire a qualified contractor or carpenter to handle the installation. Remember, a chain is only as strong as its weakest link, and a header is only as effective as its installation.