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Stair Stringer Attachment

Use a metal stair stringer hanger to secure stair stringers to a deck. The International Residential Code prohibits end-nailing, toe-nailing, and screwing of stringers to headers. Metal hangers must utilize nails or fasteners of the correct size, as specified by the maker of the hanger. Failure to properly attach a stair stringer can result in catastrophic injury to one or more individuals; therefore, a suitable fastener is essential to your new deck build. Simply "winging it" with the available fasteners is insufficient.

This article will cover all you need to know about attaching stair stringers to a deck, including helpful hints that will ensure the task is done correctly every time.


How To Attach Stair Stringers to a Deck

Despite the fact that toe-nailing or end-nailing a stair stringer to a joist is prohibited, there are numerous safe methods for attaching a stair stringer to a deck. You may employ lag bolts, carriage bolts, more posts, or an enlarged rim joist.


Read more: Closed Stair Risers


Attaching Stair Stringers to Rim Joist

The easiest way to attach stair stringers to a deck is to use hangers or lag bolts to attach them directly to the rim joist. There are numerous sorts of available hangers, so we will discuss the installation instructions for each.

With Adjustable Simpson Stair Stringer Hanger



Using Joist Hangers



Use Rafter Hangers



Attach Directly to Rim Joist

If you don't want to use hangers of any kind, you may simply use lag bolts with a diameter of half an inch to attach the stringers to the rim joists instead. Because you want to drive the lag bolts at least two inches into the stringer end, you'll need to use four-inch long bolts.

You will need at least two lag bolts in order to use them as the primary method of stringer fastening when you are installing them. However, you will also require washers that are compatible with the half-inch lag bolts in order to protect the rim joist from being damaged. As you screw the lag bolts into the stringer, there is a possibility that the stringer will split or twist, thus it is recommended that you pre-drill the holes beforehand.

When you want the stringers to extend the deck surface, utilizing the top tread of the stringer as a deck extension and the second-stringer tread as the first step, the best time to use this type of stringer attachment is when you are doing so.


Extended the Rim Joist

If you want the top tread of your stair stringer to serve as the first step down, you will attach your joist hangers to the rim joist at a low height. You will likely install them too low, beyond what the coding allows. Code permits a minimum of sixty percent contact on the rim joist. To drop a rim joist, you will simply put a second joist of the same size beneath it. The attachment of the drop joist requires backer boards. Use 2x material of the same size as the joists. Cut two pieces to suit the rim joist and drop the rim joist's width. If you have 28 joists, this will be somewhat less than 15".


Place the two backer boards flush with the top of the rim joist behind the rim joist. To attach the backboard to the rim joist, use 3" lag bolts with washers. Use two lag bolts to secure the backer board to the rim joist and another two to secure it to the drop joist.


Additionally, you should consider installing blocking between your rim joist and the adjacent joist. This will strengthen the link between the stair stringers and rim joists and evenly distribute the stair weight across the deck framework.


Use the same size lumber when adding blocking as your existing joists. Cut them to fit the space between the rim joist and the next internal joist perpendicularly. Employ joist hangers to secure the blocking.


Ledger Board on Posts

If you do not wish to suspend the drop joist from the rim joist, you can use posts to form a ledger board for the stair stringers. Two poles will be placed on either side of the stairs. Either under the deck, right behind the rim joist, or in front of the rim joist. The aim of the posts is to facilitate the attachment of a ledger board of the same dimensions as the rim joist right beneath the rim joist. This allows you to fasten your stair stringers lower so that the top tread of the stairs is not flush with the deck surface and is instead the first true step. Place the two backer boards flush with the top of the rim joist behind the rim joist. To attach the backboard to the rim joist, use 3" lag bolts with washers. Use two lag bolts to secure the backer board to the rim joist and another two to secure it to the drop joist.


Additionally, you should consider installing blocking between your rim joist and the adjacent joist. This will strengthen the link between the stair stringers and rim joists and evenly distribute the stair weight across the deck framework. Use the same size lumber when adding blocking as your existing joists. Cut them to fit the space between the rim joist and the next internal joist perpendicularly. Employ joist hangers to secure the blocking.


The ledger board must be attached to the posts using 3" lag bolts with a 1/2-inch diameter and washers. Per post, ensure that two bolts are inserted through the back of the ledger board and into the posts. Alternatively, you can connect the ledger to the posts with galvanized corner brackets and nails indicated for that hanger type - one corner bracket per ledger/post junction.


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