Introduction
Unlike other structural components of a deck, the deck ledger board is rarely seen. Hidden away between the exterior home wall and deck joists and without notability or fanfare, the deck ledger board does its job of securing your deck to the main structure of your home. In this article, we delve into the significance of deck ledger boards and shed light on their importance in the world of deck construction.
What exactly is a deck ledger board? The deck ledger board is a horizontal piece of lumber that is securely attached to the exterior wall of a house or structure. It acts as the primary connection point between the deck and the main building, transferring part of the weight of the deck safely and efficiently. The ledger board provides critical support for the deck joists and ensures that the deck remains securely attached to the structure. Note that in free standing decks, there generally is no ledger board.
The weight of a deck needs to be translated to the ground. In general, this is partly accomplished by transferring the weight through posts into footers on which the posts sit. However, some of this weight can be transferred into the main home structure via a ledger board. It is critical that the ledger be very secure. The key to the functionality of a deck ledger is the bolt pattern.
The deck ledger is a critical component of the structural integrity of your deck. If you are unsure of what you are doing, consult with a qualified professional, such as a licensed contractor, structural engineer or your local building inspector. They can provide expert guidance and ensure that your deck ledger board is installed correctly and safely.
Deck Ledger Installation
Building authorities have a lot to say on the installation of deck ledger boards. Adhering to these codes and guidelines ensures that the deck meets the necessary standards and provides a safe, secure and reliable outdoor living space. Be sure to check with your local building department when starting your project.
In this article, we will look at 2021 International Residential Code Section 507. The ledger must be minimal 2×8 pressure treated southern pine. One other thing to keep in mind is that the ledger can’t be bolted only into a stone or brick veneer but needs to be bolted through siding into the home interior band joist. More on this later. There are some requirements on the band joist as well. It must be 2 inch nominal solid sawn spruce-pine-fir or better or 1 inch nominal engineered wood.
Ledger Bolting
When it comes to bolting the ledger to the band joist, there are more requirements. First off, you need to use exterior grade fasteners – hot dip galvanized or stainless steel. The bolt spacing is given in table 507.9.1.3(1). The following table is given for demonstration purposes. Please be sure to check with your local building department.
How to use the table above? First, the table has information for a setting with a 40 psf live load. If you have needs for heavier loads, you can refer to the full code. To use the table, look for the row with the joist span that matches your application. Then moving to the right, pick the column with appropriate bolt type. With lag bolts, you generally need a closer bolt patter. For through bolts with nuts, a wider spacing can be used. For example, for a scenario where a joist with a 10′ span, with lag screws, you would use 18″ on-center bolt spacing. With through bolts, you would use a 34″ on-center bolt spacing. Finally, for applications with sheathing greater than 1/2″ you would be required to reduce the bolt spacing to 29″. The rows of bolts must be installed in a staggered orientation.
There are also some requirements on proximity of bolts to the edge or the ledger. Table 507.9.1.3(2) covers these requirements. The bolts must be at least 2″ from the top and ends of the ledger. A minimum of 3/4″ from the bottom of the ledger is required. The row spacing must be at least 1 5/8″ but no more than 5″. Finally pay attention to the location of the bolts in the band joist. They must be at least 3/4″ from the top and 2″ from the bottom.
Brick or Stone Veneer
You should be aware of the fact that with most brick homes, the brick is technically a veneer and not a structural element. Consequently, bolting a ledger into the brick is not a good idea. As I had one building inspector tell me, “I am sure there are a lot of homes our there with the ledger anchors into the brick, and they might last 20 years, it is still a bad idea”. So what do you do in this case. Sometimes you might find you can get approved to through bolt the ledger through the brick into the band joist on the interior framing. This can still provide undue forces on the brick that could cause cracking or worse.
A much safer option is to use a solution like the Simpson Strong Tie BVLZ Brick Veneer Ledger Connector. This system uses three holes drilled through the brick (for each connector – you will need multiple depending on the width of your deck and the span of the joists the ledger is supporting). Two of the holes are used to pass structural screw through – these screws provide the vertical support. The third hole is used to run a large bolt through that rests on the band joist (but not screwed into it). This provides support against rotational forces that otherwise push into the brick. The system removes significant stresses from the brick veneer.
Weatherproofing
Installation of a ledger does open up opportunities for water penetration. The ledger board must be installed with appropriate flashing and sealing materials to create a barrier against water intrusion. By effectively preventing water from seeping behind the ledger board, it helps protect the integrity of both the deck and the house. Proper waterproofing and moisture management are crucial in preventing rot, decay, and mold growth, which can compromise the structural stability of the deck.
Conclusion
Though often overlooked, the deck ledger board is a crucial element in the construction of a safe and durable deck. It provides essential structural support, distributes the weight of the deck. It is critical that it is installed properly both securely attached to home and properly flashed to prevent water intrusion.