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A long-lasting deck requires a solid foundation; to have a foundation, we need to start from the ground up. Building deck footing can be your DIY project, or you can hire a contractor, but we believe that before jumping to the “how to” process, let’s understand “why deck footings are essential”. It is not a single component for a safe deck; various elements help it stay strong. Some of the multiple aspects are concrete deck footings, deck piers, and more. This guide will walk you through everything you need to know to get your deck off the ground safely and securely. An aesthetically pleasing deck may weigh thousands of pounds. Your deck footings transfer the weight to the soil beneath the deck, and that’s why you should make the footings large and build them with great diligence. Otherwise, you will be at a higher risk of future structural damage. To protect your deck for the long term, not only should the footings be solid, but the surface should also be protected with a quality deck sealer to guard against weather and moisture damage.
What are Deck Footings?
Deck footing is the structural foundation of a deck. They’re usually made of concrete and positioned below the frost line to avoid shifting or sinking due to seasonal changes. With footings, the terms deck footers and deck piers will also come before you. These elements work with deck footing and help elevate and stabilize the deck.A deck footing will help distribute two types of weight: Live Load and Dead Load.
Live Load
As the name suggests, “live” is the weight on the deck. It can be the weight of people, snow, furniture, plants, and other objects on the deck.
Dead Load
The weight of the deck material itself. A strong foundation for the deck ensures it won’t sag, shift, or collapse over time. Skipping this step may become an essential mistake in your deck construction. And while your footings support the deck from below, maintaining the surface above with regular deck cleaner use helps preserve its appearance and extend lifespan.
How do deck footings work?
Deck footings help stabilize the deck. Without footings, deck posts have a smaller area that can sink under the deck’s weight and compromise its structural integrity. Winter brings frost, which can freeze the water in the soil and lead to expansion in volume. This creates an upward force and a phenomenon called frost heave, which can lift and shift footings. You must install deck footings below the frost line to prevent this movement during winter. If you fail to install deck footings and the it moves due to frost heave, the structure may fall, or in extreme cases, the deck may detach from the house. Each location has different soil conditions, frost depth, and weight distribution. Depending on these elements, it’s essential to consult your local building department for specific footing requirements.
Types of Deck Footings
Deck Footings have several types, and each comes with an advantage depending on your site conditions and deck type:
Traditional Concrete Footings
Concrete footings are the most common type. Workers dig holes below the frost line and pour concrete into cylindrical forms, often called Sonotubes, to create vertical columns.
Precast Concrete Piers
These premade blocks sit on the ground and include notches or holes for beams. They’re best suited for small, low-elevation decks.
Deck Blocks
Deck blocks are lightweight and easy to install, ideal for simple or floating decks that don’t require deep anchoring.
Helical Piers
Screwed into the ground like giant corkscrews, helical piers are great for sloped or unstable soil and eliminate the need for poring concrete. Each deck footing or pier type has specific use cases, but concrete footings remain the go-to solution for most residential decks.
Planning and Codes: What You Need To Know Before You Dig
Before grabbing a shovel, it’s essential to understand your local building codes. Most municipalities require a permit for decks over a certain height, and the exact requirements for deck footers and footing depth will be outlined.
You’ll also need to:
- Call 811 or your local utility locator to mark underground lines.
- Determine your region’s frost line depth.
- Identify your soil type to ensure your deck foundation will be stable.
- Skipping this step could lead to failed inspections or worse, an unsafe structure.
Tools and Materials You’ll Need
To build proper deck footings, gather the following tools and materials:
- Post hole digger or power auger
- Shovel
- Concrete mix
- Sonotubes or cardboard forms
- Gravel
- Rebar (if required)
- Level and tape measure
- Brackets or anchor bolts
- Having everything on hand before starting will save time and reduce stress.
How to Build a Deck Footing – Step-by-Step Guide
Step 1: Mark the Location of Each Footing
Use your deck plan to measure and mark the exact location of each footing. Use stakes and string lines to create a square, level outline.
Step 2: Dig the Footing Holes
Use a post hole digger or auger to dig holes below the frost line (typically 36″ or more, depending on your region). The diameter should be at least 12″, but check local code.
Step 3: Add Gravel Base
Pour 4–6 inches of compacted gravel at the bottom of each hole. This improves drainage and helps prevent water from accumulating at the base of your deck footers.
Step 4: Insert and Level Sonotubes
Place Sonotubes into the holes and trim them to the correct height using a handsaw. Use a level to ensure they’re plumb and consistent in height.
Step 5: Mix and Pour the Concrete
Follow the instructions on your concrete mix bag. Pour the mix into each form, tamping to eliminate air pockets.
Step 6: Set Brackets or Anchor Bolts
- While the concrete is wet, insert metal brackets or anchor bolts where your posts will be attached. Recheck for level.
- Once the concrete cures (usually 24–48 hours), your deck footing is ready to support the deck’s frame.
Common Mistakes to Avoid
Even seasoned DIYers can make errors when it comes to footings for decks. Avoid these common pitfalls:
- Not digging below the frost line, leading to frost heave
- Uneven footing heights, causing framing headaches
- Improper mix or pour, resulting in weak deck foundations
- Skipping permits, which can lead to fines or forced teardown
Conclusion
Understanding how to build proper deck footings is one of the most critical steps in your deck-building journey. A solid deck foundation keeps your structure safe, stable, and long-lasting, whether you’re building a simple platform or a multi-level masterpiece. Follow this expert guide and choose the right type of footing for your deck – concrete, piers, or deck footers. You’ll set the stage for a beautiful outdoor space you can trust for years. To ensure that beauty lasts, consider sealing the surface with a weather-resistant deck sealer and keeping it clean year-round with a deck cleaner. These finishing touches will preserve your investment and keep your deck looking new.
Frequently Asked Question (FAQs)
Q.1 How deep should deck footings be?
Footing depth depends on your local frost line—it is usually between 36 and 48 inches. Always check with your local building department.
Q.2 What is the difference between a footing and a pier?
A deck footing is the broader base that spreads the load, while a pier refers to the vertical element that connects the footing to the structure above.
Q.3 Can I use deck blocks instead of digging footings?
Yes, for small or floating decks. However, the code requires concrete footings or helical piers for larger or attached decks.
Q.3 Do deck footings need rebar?
Rebar (reinforcing bar) is often recommended for concrete deck footings, especially for larger decks or areas with poor soil conditions. It strengthens the concrete and helps prevent cracking under pressure. While not always required by code, using rebar can greatly improve the durability and stability of your deck foundation.
