Lateral Load Deck Connector Options

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One section addressing deck construction in the IRC has been consistent through every version. “… decks shall be positively anchored to the primary structure and designed for both vertical and lateral loads.”  The bolts or screws that attach a deck ledger to the rim joist of the house handle the vertical loads – those due to gravity.  But what are lateral loads?  Lateral loads are those that pull the deck away from the house.  A simple example is people moving around on a deck.  Quantifying lateral loads is difficult and for years there were no prescriptive designs / systems for a lateral load connection leaving deck builders and code inspectors to figure it out.

First attempt to add lateral load connectors to the building code

In the 2007 IRC code supplement a new illustration showing a lateral load connection was introduced.  It showed metal connectors fastened to a joist in the floor of the house and a joist in the deck with a long bolt or threaded rod linking the two connectors.  The code language was confusing.  Some readers thought this specific connection design was required for all decks but that isn’t the case.  The illustration was presented as a prescriptive lateral load connection that would fulfill the lateral load resistance requirement when two of the linkages are installed on a deck.

Even though the lateral load connection shown in the code wasn’t required, its publication elevated the awareness that decks needed to include lateral load resistance connections.  It’s still up to the local building department to decide what constitutes an adequate lateral load connection. The local code official has the authority to approve other methods a deck designer and builder would like to use for lateral load resistance; so check with your local building department.

Code changes make the connection process simpler

A new illustration was published in the 2015 IRC showing a simpler lateral load connection than the original.  It shows a connector fastened to a deck joist with a screw driven 3 in. into the mudsill or top plate of a wall.  Four of the connections are needed on a deck to qualify for lateral load resistance.  The connection works on new homes and simplifies new deck construction on an old house.  An important thing to note about the connection is that the code limits its use to decks where the deck joists are parallel to the house joists.  In other words, decks along the wall of a house where the house joists rest on and are nailed to the mudsill or top plate.  It can’t be used on decks connected to walls where the joists run parallel to the rim joist.  Your local building official does have the authority to permit using the connection along these walls but that would be on a case-by-case basis.

Lateral load connection articles

• Attach a Deck to Any Wall
• A new code requirement for decks
• New Lateral Load Connection in 2015 IRC
• Retrofit Lateral Load Connection for Decks
• Attaching a Deck
• Simpson Strong-Tie DTT1Z Deck Tension Tie
• MiTek LTS19-TZ Deck Lateral Load Connector

Hardware information

• MiTek/USP: Deck Tie Back DTB
• MiTek/USP: Adjustable Deck Tension Tie  ADTT-TZ
• MiTek/USP: LTS19-TZ
• FastenMaster: LTS (lateral tension system)
• Simpson Strong-Tie: DTT-1, DTT-2
• Simpson Strong-Tie: Installation Options for Deck Lateral Load Connections