If you're in the planning stage or in the middle of constructing your deck stairs, you might wonder, how you can securely attach it to the ground. Don't worry, you are in the right place! We researched if your deck stairs need footings, and here is what we discovered.
Yes, you need to have footings for your deck stairs. However, to know how deep the footing is, you have to refer to your local building codes.
Keep reading as we discuss what factors, aside from local building codes, affect the depth of your deck stair footing and when it is not necessary to have one. We'll also share with you how much load your footings should carry. Additionally, we'll share tips to remember when you install your deck stairs footings and the types of landing you can install.
Why Are Footings Necessary?
Footings counteract the impacts of frost heaves on your deck stairs. So, if the frost line is above your footing's lowest point, your deck stair footing will not be affected by the freeze-thaw cycle of the soil.
Additionally, to reduce movement over time, deck stair footings are now required by building codes.
What Happens When The Deck Stair Footing Is Above The Frost Line?
The landing area is where a deck's staircase meets the ground. It could be atop a concrete slab, crushed stone, or a patio, for instance. Eventually, the shifting earth caused by frost heaves will also disturb the landing area. As the landing moves or shifts to adjust to soil fluctuations, the stairs will also move slightly.
Longer staircases, particularly those spanning multiple flights, might move more readily than shorter staircases with only a few steps. Those longer staircases rely on footings beneath the frost line to keep them stable.
How Much Load Can A Deck Stair Footing Carry?
By default, footings are assumed to carry a live load of 40 lbs/ft² and a dead load of 10 lb/ft².
So if this load is distributed across the allowed area for solid stringers, which are 18" and half the maximum span- typically 13' and 3", you will get a total load of 500 pounds.
How Deep Should Your Deck Stair Footings Be?
Installing footings below the frost line minimizes the stairs' ability to shift. This is particularly important if the deck is attached to the house using a ledger or if you have a tall staircase. But how deep is the frost line, or area where ground water freezes? It varies by region.
You'll want to determine frost line depth for your locale by talking with a local contractor or reviewing the contour lines on the National Weather Service's Frost Depth map. Install your footings deeper than that.
But if the deck is freestanding from the house, the minimum stair footing depth should only be 12".
What Is The Ideal Size Of A Deck Stair Footing?
According to the stair footing detail of the DCA6 Guide of the American Wood Council, the recommended shape and size is a 10" x 10" square or a circular 12" diameter footing with a 4" x 4" post.
Also, the minimum thickness of your footing is 6".
When Does A Deck Stair Need An Additional Footing?
Over 6' long stairs should have intermediate support.
Solid stringer stairs shouldn't be longer than 13' in length. Remember that this is the horizontal distance from the top of the stairs to the commencement of the last riser, not the length of the stringer itself.
The same rules that apply to footings supporting a flight of steps must be followed. It states that each stringer should be joined by a horizontal 4" x 4" post that is mounted on footings. The code mandates that every post be notched so that it can fit beneath and next to the stringer.
Horizontally place 2" x 6" supports underneath the stringer and form an x-brace with two 2" x 6" to stabilize the lateral side of the structure.
How Do You Connect The Footing To The Base Of Your Deck Stairs?
Here is a simple guide to fasten your deck stairs to the footings:
1. Install A Baseplate
Through-baseplate installation is one of the simplest methods for securing deck stair footings to concrete. This base plate is usually a 2"x4" piece of wood.
It will be possible to securely tie your steps to the footings because the footings will make complete contact with the baseplate.
2. Secure The Baseplates With Anchor Sleeves
These are special bolts made for concrete and masonry. Use anchor sleeves with a minimum diameter of 1/2 inch and a minimum length of 6 inches.
When you drill a hole in your baseplate, use a concrete drill bit. Make sure that you drill deeper than 6 inches to ensure that the bolt penetrates fully.
3. Put The Sleeve To The Hole And Finish Up
Now, drive the sleeve to the hole using a hammer to firmly set it. Depending on the kind of anchor sleeves you choose, finish the process by tightening the bolt with a socket, wrench, or screwdriver.
Pro tip: When buying anchor sleeves, choose stainless steel since they are used for outdoor use.
What Are Some Tips That Might Help When Installing A Deck Stair Footing?
Here are some tips you can use when you're installing your deck stair footing.
Place the Stringers Beforehand
Before deciding where to dig for your footing, you must first install the stringers. This way, you can make sure that the footings will be set up in the right place and smoothly connect with the stringers.
The Number Of Footings You Need Is Dependent On The Stringers
At the very least, you only need one footing under each stringer (that's a minimum of two). But if the stringers you have is more than five, then you might need more footings.
Choose Your Landing Style
Make a decision regarding the landing you will have. In contrast to other landing styles, a concrete pad doesn't need its footings to elevate beyond grade.
Is It Worth It To Have Frost Footings For Your Deck Stairs?
To help you decide whether it's worth it or not, here are some pros and cons of having frost footings:
- Frost footings serve as concrete support that goes beyond your local frost line.
- The footings will improve security and reduce the chance that the steps would collapse by ensuring that the movements of your stairs will be at the slightest.
- It takes a significant amount of labor and excavation work to construct them.
- The gain you would obtain would not outweigh the cost of installing one if the length of your stairs is short.
What Are The Landing Options You Can Choose From For Your Deck Stairs?
Due to its strength and permanence, concrete is typically the best choice. However, there are other options such as pavers, bricks, and flagstones.
You can refer to the table below to know the differences between them, their advantages, and their disadvantages.
When Is It Not Necessary To Install Footings For Your Deck Stairs?
You can choose not to install footings if your deck stairs are fewer than three risers.
If a footing is not required, here are some of the acceptable stringer materials you can choose from:
- patio bricks,
- a wooden landing pad, or
- any other material that will prevent the ends from decaying.
Just keep in mind that you must not tie your deck steps to your floating landing pad if you decide against installing footings for them.
By attaching them, you could potentially jeopardize the structural integrity of your stairway and make your stairs extremely vulnerable to frost heaves or other types of ground movement.
When you have deck stairs with more than three steps, you need to have footings. Also, you should consider the freeze-thaw cycle of the soil. So, you must know the frost line of your area and place the footing deeper than that.
However, if your deck stairs only have three steps, then it's not necessary to have footings to support them. Additionally, there are a few landing material options you can choose from. You can either install concrete, paver, brick, or flagstone.
Finally, always consult with your local community codes to make sure that you are not violating any laws in your area.
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