If you are building stairs, you are likely going to need to attach them to a concrete landing. In this article, I am going to show you the best way to attach stair stringers to concrete so that your stairs are sturdy and safe. Whether you are building deck stairs, playhouse stairs, or stairs that lead to your front door, this article will ensure that you stairs are properly attached to the concrete landing.
If you are more of a visual learner, you can watch my YouTube video which shows the entire process for building exterior stairs and attaching them to a concrete landing.
The Two Options for Attaching Stairs to Concrete
To attach the stair stringers to concrete, you really have two options:
Option 1: Install Blocking Between Each Stringer (Easier)
For this option, use 2”x6” or 2”x8” pressure treated lumber and cut it size based on your stringer spacing. For example, if your stringers are going to be placed 16” On Center (O.C.), you would cut your blocking to 14.5”.
Next, place the blocking between the stringers and screw it into place on both sides. Note that you may need to “toe-nail” in some of the screws to avoid conflicts with the already installed pieces of blocking.
With all of the blocking installed, your stair stringer assembly at the concrete stair landing should look something like this:
Option 2: Notch the bottom of the stringers and install one mounted board (More Solid)
Option 2 is the Method I typically use. It’s a bit more work, but it makes for a super solid set of exterior stairs.
For this method, cut a notch out of the bottom of each stringer that matches the depth and width of the mounting board (2”x6” or 2”x8”). For example, if you are installing a 2”x6” mounting board, you would cut a 1.5” deep by 5.5” (these are the actual dimensions of a 2”x6” piece of lumber) wide cutout at the bottom of each stringer.
Next, cut your mounting board to the length of your total stair assembly and then attach the mounted board to the stringers using a few screws.
PRO TIP: If you want your exterior stairs to last *forever* notch out a slightly deeper cutout at the bottom of the stringers so that you can install a piece of PVC board below the mounting board. PVC is rot resistant and will help to prevent the bottom of your stair strings from rotting out prematurely. I also like to cutout the back of the stringers so that I can install a small PVC piece at the back as well. This method is covered in detail in my YouTube Video.
– Andrew
Attaching the Stair Assembly to the Concrete
Now that you have the bottom of the stair stringers connected (Either by option 1 or Option 2), it’s time to attach the stairs to the concrete.
After positioning the stairs where they need to be on top of the concrete landing, use a hammer drill with a carbide bid to drill though the mounting block and into the concrete. Repeat this process between each stringer.
The depth and size of your pre-drill will depend on the type of concrete anchor you are using to secure your stairs to the concrete. There are various different types of concrete anchors (Wedge / Expansion Anchors, Screw Anchors, etc.) and the box will say what size and depth to pre-drill.
PRO TIP: Ensure that the anchor will extend a minimum of 2” into the concrete.
After predrilling though the stairs and concrete in all of the locations needed, use a drill to install the concrete anchors. For my project, I used Power Pro Concrete Anchors wich required a ¼” bit with a 5.5” deep pre-drill.
As you screw in the concrete anchors, you will typically feel the stair stringers “lock” into place as tighten them.
Repeat this process for all of the screws needed for your staircase. I had a 48” wide staircase for my deck and I used 5 concrete anchors to attach the bottom of the stair assembly to the concrete landing.
Here is a look at the stairs secured to the concrete landing:
And here is a look at the stairs once the project was completed and trimmed out:
For more information on building stairs, check out my “How to Build Deck Stairs that will last Forever” YouTube video.
Additionally, if you are building a deck, I have a completely free “How to Build a Deck” Ebook that will explain every aspect of the deck building process in an easy to digest manner. You can find this at the link below my YouTube Video.
I hope this article has been helpful and good luck with attaching your stairs to concrete!
DISCLAIMER: This is a reference guide only. Consult local code requirements. Links included in this article might be affiliate links. If you purchase a product or service with the links that I provide, I may receive a small commission. There is no additional charge to you! Thank you for supporting ATimprovements so I can continue to provide you with free content each week!