Deck Ledger Boards – Everything You Need To Know

A deck ledger board essentially holds the deck back to the building where the deck meets the building at the elevation of height of the deck framing just below the floorboards of the deck.  Today we’re going to look at some of the most common typical Problems with deck board installations and the. Requirements for proper construction and best practices.  The outline of this report follows below.

1. Building Code Requirements
2. Best Practices in Ledger Board Installation
3. Bolting Patterns and Techniques

Building Code Requirements:

Deck ledger board installation must adhere to specific building code requirements to ensure a secure structure. Building codes dictate the sizing specifications for deck ledger boards, prescribing dimensions that meet safety standards. Additionally, precise spacing requirements for bolts, along with specified patterns, are outlined to guarantee proper attachment to the main structure. The building code establishes standards for joist spacing, a critical factor in maintaining structural integrity and preventing potential hazards.  Sounds simple, BUT it isn’t the way that the building code works, it specifies different requirements for different configurations and there are modifications and variations in different municipalities throughout the USA, so training and experience are very important.  The average homeowner may find reading through the code book to determine applicability of each requirement daunting. 

Even though it isn’t simple, professionals can learn the heuristic rules of thumb that will keep their work safe and they can also learn how to navigate through the code requirements, in time.

Best Practices in Ledger Board Installation:

Going beyond the minimum requirements of building codes, discussions on ledger board installation delve into best practices that elevate the overall structural stability and durability of the deck. A good builder makes it their goal to build to last, albeit price and budget are often the enemy of very long durability materials.  The list below includes a handful of better or best practices that increase quality and longevity of a deck:

1. Proper Flashing Installation:  The installation of a high-quality flashing at the top of the ledger board is often omitted by cheap contractors, but it is important. This deters water infiltration between the back of the ledger board and the exterior wall of the building.  
2. Use of Lag Screws Instead of Nails:  It would be rare for a pro to use nails to connect a ledger board to a substrate building wall, but make sure to opt for lag screws instead of nails for attaching the ledger board to the main structure. Lag screws offer superior shear strength and durability, providing a more secure connection.  
3. Durable Ledger Board Material:   Choose ledger board material that is not only compliant with building codes but also durable and resistant to decay. Common choices include pressure-treated lumber but alternative chemical treatments may be available as well.
4. Elastomeric Sealant for Bolt Holes:   Apply elastomeric sealant to bolt holes in masonry substrates. This prevents water from seeping into the holes, reducing the risk of moisture-related issues over time.  This provides a defense to water entering through the bolting locations into the building wall which will prevent unnecessary rot to internal building materials.
5. Regular Inspections and Maintenance:  Conduct regular inspections of the ledger board and surrounding components. Promptly address any signs of wear, damage, or water damage to ensure ongoing structural integrity. If you, as a homeowner are unable to check this yourself, work with a good company like DupontDecksPatiosDC.com
6. Proper Joist Hanger Installation:  Use joist hangers for attaching deck joists to the ledger board. Ensure they are properly installed according to manufacturer specifications to provide optimal support.  Errors and omissions in the deck hanger installation is so prolific that we could write and entire series of articles just focusing on this particular area of defects.
7. Plates or Washers:  Use extra large and/or extra thick fender washer or plate style washers at each bolt installation locations. Bolts in kits such as lag or wedge anchor type kits do not generally include oversized washers. However, oversized washers, in this particular case, will allow an extra strong heavy force or load to be applied to the ledger board and the large plates will resist beam splitting or tear through all those bolts locations better than they would without the extra large oversized plates plates.
8. Weatherproofing:  Apply a weather-resistant coating or sealant to the ledger board to protect it from the elements. This extra layer helps extend the lifespan of the ledger and enhances overall durability.

Bolting Patterns and Techniques:

In deck ledger board installation, it’s a common requirement is to use lag screws or bolts with a diameter and length compliant with code standards. A typical specification might be to use ½-inch diameter bolts spaced at intervals not exceeding 24 inches along the ledger board.

Example:

• Bolting Pattern: Place bolts or lag screws horizontally along the ledger board, ensuring each bolt is no more than 24 inches apart.
• Technique: Use a staggered pattern, alternating bolts above and below the ledger. Bolts should penetrate through both the ledger and the underlying structure, such as the rim joist.

This approach, adhering to the specified diameter, spacing, and penetration depth, ensures a secure and code-compliant bolting technique. While the actual requirements may vary based on local building codes, the emphasis is on clarity and precision in implementing a practical bolting pattern for a stable connection.

A staggered pattern spreads the load across a larger area of the ledger board and the underlying structure. This helps prevent concentrated stress points that could compromise the integrity of the wood.  Ledger boards, particularly those made of wood, are susceptible to splitting, especially when subjected to heavy loads. Staggering the bolts reduces the likelihood of creating continuous lines of weakness, minimizing the risk of splitting.  The staggered arrangement enhances the overall stability of the connection. By avoiding a concentrated aligned pattern, potential weaknesses associated with a straight line of bolts are mitigated, contributing to the overall attenuated pressure of the attachment.  This attenuated load distribution translates to a higher strength of the connection.

In the near future, in the following upcoming articles on our website we will also discuss other details related to deck ledgers and associated best practices and connection and sealing:

• Joist Spacing Requirements
• Flashing and Sealing

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