Ask any deck builder the most likely place a deck will fail and, odds are, they’ll point to the ledger board. If not correctly installed and protected, this single structural element can be the Achille’s heel of a deck resulting in premature deterioration or collapse.

Over the past 30 years, I’ve seen my share of questionable ledger applications and have identified four common – and easily avoidable – mistakes:

1. Improper Attachment

Correct anchoring of the ledger board is crucial to a deck’s composition and safety. For optimal support, the ledger board must be attached to the rim joist. It is also important to use the right fasteners (see more on this later).

2. Incorrect Joist or Beam Spacing

Because the weight of a deck is distributed per square foot between the joists and the ledger board, the importance of accurate spacing between joists and beams cannot be overstated. Leaving too much space between these bracing elements is a recipe for disaster. Be sure to follow IRC guidelines as well as any instructions provided by materials manufacturers.

3. Using the Wrong Fasteners

This mistake is quite common whether due to misinformation or cutting corners. For ledger applications, it’s best to use hex or carriage bolts. Lag bolts and nails can more easily strip out of wood. I’ve heard of cases where builders have been able to pull a deck away from a house with just a good yank because the original installer used nails that had corroded. Look for sturdy metals such as stainless steel or hot-dipped galvanized that are resistant to rust and corrosion. I also recommend applying our butyl joist tape to help keep screws dry and in place.

4. Neglecting to Waterproof

Easily one of wood’s worst enemies, moisture is a recurring theme across ledger board failures. In most deck installations, there is a gap left between the house and the deck that allows water to seep down onto the ledger board where it can penetrate the wood and lead to decay. This is why it’s critical to protect the ledger with waterproof flashing.

While there are several types of flashing available, only tapes have the ability to create a waterproof seal. These self-adhered membranes also eliminate the need for fasteners that create holes, and they won’t corrode.

Trex Seal represents a new generation of waterproofing membrane that combines the best performance features of metal and tape flashing. This aluminum-lined tape comes in sizes to protect the entirety of the ledger board. An 11”-wide tape provides complete coverage of the ledger board face and also seals any gaps between the ledger and the substructure. A 22” sub-ledger tape creates a continuous water-tight seal between the ledger and the housewrap to prevent water from infiltrating the house. Both products feature convenient release liners for easy and accurate application and are Code AAMA711 compliant. These extra layers protect the ledger board on all sides significantly reducing the likelihood of wood decay and increasing the lifespan of a deck.

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About the Author

Dave Kile is owner and CEO of IBP, LLC, which manufactures and markets some of the decking industry’s most successful waterproofing innovations, including Trex RainEscape, Trex Protect and Trex Seal under a Trademark License Agreement with Trex Company, Inc.