Just like a concrete foundation is needed to support your home, concrete deck footings (also known as “footers”) are required to support your deck. They distribute the weight of the deck and prevent shifting or sinking over time (if done correctly, that is…).
In my last article, I walked you through the process of locating and marking the locations of the concrete footings based on Internation Residential Code Section R507. That article is linked here.
In this article, I am going to show you how to dig and pour the concrete deck footings after they have been marked.
As always, you can watch my “How to Pour Concrete Deck Footings” YouTube video linked below if you are more of a visual learner:
Tools and Materials Recommended for any Concrete Deck Footing Project
- Concrete Form Tube (Sonotubes, etc.) – The link is just an example.
- Concrete – Just an example. Buy concrete from your local big box store.
- Concrete Mixer (If concrete is not being delivered) – I recommend that you rent a mixer.
- Auger or Post Hole Digger
- 4×4 post (for compacting)
- Shovel
- String Line
- Level
Footing Depth and Dimeter Considerations
When it comes to concrete footings, there are two things that you need to be aware of:
- Frost Depth: Footers need to extend below the frost line in your area (30” in Maryland) to avoid heaving during freezing and thawing. The frost depth can vary based on your geographical location but is typically between 24–48 inches deep. To find the frost depth in your area, check with local building authorities.
- Footing Diameter: The diameter of you footing is based on code requirements – but most footings are 12” in diameter. Concrete form tubes (also know as Sonotubes) are cardboard concrete form tubes that come in various diameters. They create a stable, round concrete footer and are ideal for decks that are elevated. The tube will keep the concrete in place until it hardens.
Below is the process for digging and installing concrete footings:
Digging and Excavating for the Concrete Footings
If you are only digging a few concrete footings for your deck, you can dig the footing holes by hand using a shovel and a post hole digger.
However, this process is very time consuming and labor intensive. Instead, I recommend that you rent an auger to dig your footing holes. Since I had 23 footers for my deck (Yes, you read that right and, yes, it was way too many..), I rented a skid steer with an auger attachment to dig all of my footings.
PRO TIP: If you rent your equipment on a Friday, you can sometimes keep it for the entire weekend and return it on Monday morning and only pay for a One-Day rental. However, check with your rental company.
However, this is likely overkill for many deck projects and a smaller auger like the one pictured below might be a better bet.
As noted above, the frost depth in my area is 30”. As a result, I dug down to around 34” and then compacted the bottom of the hole using a 4”x4” piece of lumber as a tamp.
Remove and loose dirt from the bottom of the footing (using a post hole digger) and then compact the bottom of the footing hole
I then backfilled with around 4” of stone and tamped the bottom again. This stone will help the bottom of the footing to be better compacted and will also help to prevent water from accumulating at the bottom of the hole.
Installing the Concrete Form Tubes
Once the footing holes have been dug the required depth, Place the concrete form tubes into each hole, ensuring the tube is vertical and level. The tube should rise slightly above the ground surface to keep water off.
PRO TIP: Since my footing hole is 30” deep, I cut my form tubes to 33” so that around 2” of the concrete footing would be sticking up out of the ground.
After confirming that the concrete form tube is plumb and level, backfill around the edge of the hole with dirt to hold the concrete form tube in place. It is usually a good idea to re-check that the tube is plumb and level after backfilling.
Mixing and Pouring the Concrete Footings
With the concrete form tubes in place, it’s time to mix the concrete and pour it into the form tubes. If you are only installing a few footings, you can typically get by with mixing the concrete by hand in a wheel barrow.
However, if you have a lot of concrete footings, you should consider one of the following concrete mixing / pouring options:
Concrete Delivery: Consider ordering concrete via a concrete truck delivery service and they will be able to pour (or pump) the concrete directly into all of your footings. This is definitely the easiest, it will just cost a bit more.
Mixing the Concrete with a mechanical mixer: You can rent a mechanical drum mixer or a device called the “Mud Mixer” which will make it 10X easier to mix your bagged concrete on site.
I mixed over 100 bags of 60 pound concrete bags using the Mud Mixer.
Pour concrete into all of the form tubes, filling them up to the top. Use a rod or piece of rebar to mix the concrete as it is poured into the footing to remove air pockets. Finally, screed the top of the form tube flat and finish the surface using a concrete finishing trowel.
VERY IMPORTANT: Eventually, you will be installing post hardware on top of your footings. You can either install a wet-set concrete anchor that you will insert at the same time you pour the concrete OR you can install a concrete wedge anchor after the concrete dries (refer to my YouTube Video). If you are going to wet-set your concrete anchor, ensure that you place into the wet concrete before it cures.
Ensure that the hardware is in line with your sting line (set previously during the planning stage) and that the bolt is not too low or sticking up too high.
Allow the concrete to cure for at least 24–48 hours before installing the post anchor hardware. To install the post base hardware, position the base plate over the threaded bolt and then place your washer and nut over the bolt. Tighten everything up using a socket wrench.
For more information on attaching the posts and post hardware to the concrete footings, check out my blog article linked here.
Note that I also installed landscape fabric and stone underneath my deck around the footings. This will help to prevent the area under my deck from getting muddy when it rains. In some states, the landscape fabric and stone installation under the deck is a code requirement.
With all of the deck footings and post hardware installed, we can begin the deck framing process. If you are going to be framing your own deck, consider checking out my “How to Frame a Deck” Blog Linked here.
Additionally, if you are more of a visual learner, you might find my “How to Dig and Pour Concrete Deck Footings” YouTube to be helpful!
Thanks for reading and good luck with your deck footing project!
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!