Are you building a deck, but not sure how the stairs are going to attach? Like any solid structure, your steps need a stable foundation. There are many options when it comes to footings for your deck steps, from concrete and gravel to patio stones and even grass. But do deck stairs need footings?
Your deck stairs are going to need footings. First, you need to consult your local building code. The depth of your footing will depend on where you are geographically. Colder climates will require deeper footings. Once you have your footings, a concrete lintel or pressure-treated base plate is used to secure the steps to the footings..
In this article, we’ll look at different types of footings for deck stairs as well as construction tips to ensure your stairs are as solid as your deck.
Do Deck Stairs Need Footings?
Let’s be clear – footings and a landing pad or wooden box are not the same thing. Typically, most North American building codes require all deck steps to terminate on a minimum 3×3 foot landing pad. If your backyard is extremely flat, the code will allow you to forgo a landing pad.
Footings go beneath the landing pad. Generally, footings are concrete and poured into long cardboard tubes. These tubes go beneath load bearing points in your structure. On your deck, they support wooden posts that hold up beams.
Footings are necessary because they negate the effects of frost heave. If the lowest point of a footing is below the frost line, it will not be susceptible to the shifting of water freezing and thawing in the soil.
Just as decks are susceptible to frost heave, so are stairs. If you take the time to properly protect your deck from frost heave with footings at an appropriate depth, wouldn’t it make sense to do the same with your steps? Building codes are now requiring deck stair footings to minimize stair movement over time.
Footings with Different Deck Stair Landing Options
Now that you know you need footings, what are your stairs going to sit on? Several options include:
- Concrete landing pad
- A wood box-type landing pad
- Crushed stone
- Patio Blocks
Stairs that are 36” wide will require a landing at least that wide, and preferably a few inches more on either side. The length of the landing should be similar, for both practical and aesthetic purposes. You’ll want a landing that you can step on, and then take at least one more step before you move to a different surface.
Your stair stringers will rest on your landing pad, but you should include a base plate. A bearing block is typically a 2×4 that connects your stringers. It requires you to cut a 2×4 profile at the end of each stringer so that your stairs are resting on that piece of wood.
This block will rest on the footings or concrete pad. It adds structural support to your steps and ensures the width of the steps are evenly spaced and level.
A concrete landing pad is the sturdiest option. However, it is also the most labor-intensive. If you are planning on installing a concrete landing pad, you’ll want to account for this when you pour your stair footings. Since your stair stringers will sit on the pad, and not the actual footings, you’ll want to subtract from the footing height to account for the thickness of the landing pad.
Wood landing pads are easier to build. Using pressure-treated lumber, you can sit some deck boards on top of 2×4’s or larger planks, to create your landing space.
The stringers will still rest on the footings; you will just build your box around the last step. Wood landing pads should abide by the same rules as concrete, making them at least 3’x3’.
If the ground where your stairs terminate is level, then a landing pad is not necessary. Adding crushed stone of any variety is one way to nicely cover up any evidence of the footings beneath your stairs while adding aesthetic value.
Similar to crushed stone, patio blocks placed around the last stair can also work. However, they should only be used on level ground. If you are installing patio blocks, be sure to prep the surface beneath them first.
You can sit patio blocks on top of the footings, and have the stringers terminate on the patio blocks. This will make it easier to create a level landing of blocks.
Footings for Extra-Long Deck Stairs
A set of stairs with solid stringers should not run more than 13’ in length. Keep in mind this isn’t the length of the actual stringer, but the horizontal length from the start of the stairs to the beginning of the final riser. Stairs longer than 6’ in length should have intermediary support.
When supporting a set of stairs, the same rules apply to footings. 4×4’ posts on footings should run vertically and attach to each stringer with #8 wood screws. Notching each post to fit underneath and beside the stringer is required by code. A horizontal 2×6 should connect the posts under the stringers, and two 2×6 cross pieces for an x-frame beneath for lateral stability.
Installing Deck Stair Footings
Installing deck stair footings is similar to the process you used to install footings for your deck posts. However, calculating exactly where your stair footings will go in relation to the deck is trickier. Here are some tips to consider when installing deck stair footings:
- Install your stringers before you put the footings down. This will help you identify where you need to dig your holes and place your tubes.
- At a minimum, you will need two footings, one beneath each outside stringer. More may be required if you have more than 5 stringers.
- Determine what type of landing you are going to have. A concrete pad does not require the footings to rise above grade like other landing types.
Attaching Deck Stairs to Footings
One of the easiest ways to attach deck stair footings to concrete is through the base plate. As mentioned above, the base plate is the horizontal piece of wood, usually a 2×4, that connects the stringers at the base of the stairs. The footings will make full contact with the width of the baseplate, providing an excellent opportunity to fasten your stairs to the footings.
Using anchor sleeve bolts, attach the stairs to the footings. Anchor sleeve bolts are special bolts designed for concrete and masonry. They require a hammer drill with a drill bit the same diameter as the bolt. You will want to use at least ½” diameter anchor sleeves, no less than 6” in length.
Drill a hole through your base plate into the footing using a concrete drill bit. Drill further than 6” to ensure your bolt makes full contact with the concrete.
Then push your sleeve into the hole. Use a hammer to set it fully into the hole. Finish the job by using a wrench, socket, or screwdriver to torque the bolt into place depending on the type of anchor sleeves you buy.
Remember to buy the stainless steel anchor sleeves, which are made for outdoor applications, unlike zinc.
When are Deck Stair Footings Not Necessary?
If you think that footings are a lot of work for your small flight of deck stairs, then you might be right. If you have less than 3 risers, then you do not need footings for your deck stairs.
In this case, you can get away with setting your stringers on patio blocks, crushed rock, a wood landing pad, or anything else that will keep the ends of your stringers from rotting.
Will your stairs move in the winter? Probably, but the movement won’t be great. Besides, if you don’t attach the bottom of your stairs to whatever they are sitting on, then your stair bottoms will move freely and likely settle back into place later in the spring.
Remember, if you opt-out of footings for your deck stairs, then it is imperative you don’t attach them to your floating landing pad. Attaching them will make your stairs highly susceptible to frost heaves or other ground movement and potentially compromise the integrity of your stair structure.
Your deck stairs are part of your overall deck structure. If your deck is anchored to the ground using footings, then do the same for your steps. Don’t risk having deck stairs that want to move in opposition to the rest of the structure.
Even though deck stair footings add more labor time onto your project, view them as an opportunity to create greater aesthetic appeal for your steps. A concrete slab or wood landing can enhance the look of your stairs while providing a stable, long-term platform.