How to Use Concrete Deck Blocks to Build a Deck

Using concrete deck blocks for posts can be a convenient and cost-effective way to support decks, sheds, or small outbuildings. But before you tackle this project for yourself, you want to make a game plan, assemble the right tools, and make sure you have quite a bit of time to get the job done right. 

Gathering the Right Tools for the Job

Here are the tools you’ll need for this project:

• Concrete Deck Blocks
• Posts suitable for the load they will bear and cut to the appropriate length for your project
• Level
• Measuring Tape
• String or Chalk Line
• Gravel or Crushed Stone
• Tamper 
• Pressure-treated Lumber or Beams
• Saw
• Fasteners
• Drill and Bits
• Protective Gear (e.g., safety glasses and work gloves)
• Concrete Mix and Water

How to Use Concrete Deck Blocks for Posts

From our team of experts, here’s a step-by-step guide on using concrete deck blocks for posts:

1. Prepare the Site. First, clear where you plan to install the deck blocks, ensuring the ground is level and compacted.
   
2. Layout and Marking. Determine the layout of your deck and mark the locations where the deck blocks will be placed. Use string or layout tools to ensure accurate spacing and alignment.
   
3. Dig Post Holes. Dig holes for the posts where you marked the locations. The depth will depend on your local building codes and the deck size, but typically, holes should be at least 12 to 18 inches deep.
   
4. Add Gravel or Crushed Stone. Place a gravel or crushed stone layer at the bottom of each post hole to help with drainage and prevent the posts from sinking into the soil.
   
5. Place the Deck Blocks. Set the concrete deck blocks on the ground in the marked locations. Make sure they’re level with each other. Ideal spacing for deck blocks is usually 6-8 feet apart, but that can vary based on the project specifications.
   
6. Insert Posts. Place your deck posts into the holes on top of the deck blocks. Make sure they are plumb (straight up and down) and level.
   
7. Secure the Posts. Brace the posts temporarily to keep them in place. Backfill the holes around the posts with soil or concrete mix, depending on local codes and preferences.
   
8. Check Level and Alignment. Recheck the level and alignment of each post, making any necessary adjustments so all posts are level and evenly spaced.
   
9. OPTIONAL: Concrete around Posts. If local building codes require it, or if you prefer additional stability, you can pour concrete around the posts. Mix concrete according to the manufacturer’s instructions and pour it into the post holes.
   
10. Allow Concrete to Set. If you poured concrete, allow it to cure and set according to the recommended time frame before continuing with the deck construction.

Always consult your local building department and adhere to building codes and regulations when constructing a deck. If you need clarification on any aspect of the process, consult a professional to ensure a safe and stable deck foundation.

Can You Bury Concrete Deck Blocks?

While concrete deck blocks are designed to be placed on the ground and support the weight of a deck, we don’t recommend burying them completely. These blocks are typically used as a foundation for above-ground decks, providing a stable base for the deck structure.

Burying the concrete deck blocks can lead to several issues:

1. Stability. Concrete deck blocks distribute the weight of the deck evenly across their surface area. Burying them may compromise their stability and load-bearing capacity.
   
2. Moisture Issues. Buried concrete is susceptible to moisture-related problems, including degradation and cracking. Moisture trapped around the buried blocks could lead to structural issues over time.
   
3. Frost Heave. In regions with freezing temperatures, burying the blocks can result in frost heave. As the ground freezes and thaws, it can cause the buried concrete to move and potentially disrupt the deck’s stability.

If you need a partially buried foundation, consider using concrete piers designed for that purpose. These piers often have a portion that goes below ground level to provide additional stability without compromising the foundation’s structural integrity.

Pro-Tip: Always follow local building codes and consult a structural engineer or building professional when planning and constructing a deck to ensure it meets safety and regulatory standards.

Leave the Building to UglyDeck

Building your own deck can be a daunting but incredibly rewarding feat. That said, if you want to leave the work to the professionals and you’re in the Chicagoland or Twin Cities area, we’re here to help. Since 2005, UglyDeck has been building decks for customers, providing comfortable spaces to relax and enjoy the outdoors. We are proud to offer the following services: 

• Full Deck Installation
• DIY Assist Services
• Maintenance Free Decks
• Deck Railings
• Outdoor Spiral Staircases
• Re-Deck an Existing Frame
  
  Want to get started on your own decking project? Give us a call or complete our contact form for a free estimate on your upcoming project. 

TWIN CITIES: 952-736-3308 | CHICAGOLAND: 331-300-3071