Can you build a shed on blocks?

Yes, you can absolutely build a shed on blocks, especially for smaller structures. This method is a common and often cost-effective foundation solution for backyard sheds.

However, it's crucial to understand the limitations and best practices to ensure your shed remains stable and durable over time.

When Building a Shed on Blocks is Suitable

Building a shed on a foundation of blocks, such as cinder blocks or solid concrete blocks, is an excellent choice for small to medium-sized sheds. Specifically, these types of foundations are recommended for sheds up to 160 square feet.

For larger sheds, or any portable building designed with multiple stories, a more robust and permanent foundation, such as a concrete slab or a full perimeter foundation, is highly recommended to provide the necessary support and stability.

Advantages of Block Foundations

Choosing blocks for your shed's foundation offers several benefits:

• Cost-Effective: Blocks are generally less expensive than pouring a concrete slab or installing a full foundation.
• Easy to Level: It's relatively simple to achieve a level base by shimming or adjusting individual blocks.
• Good Ventilation: Elevated sheds allow for airflow underneath, which helps prevent moisture buildup and rot in the shed's floor joists.
• Portability: If your shed needs to be moved in the future, a block foundation makes relocation much easier than a permanent slab.
• Drainage: Elevating the shed helps ensure proper drainage around the base, keeping water away from the structure.

Types of Blocks to Use

The most common types of blocks for shed foundations include:

• Cinder Blocks: Lightweight and porous, often used for non-load-bearing walls but can work for smaller sheds.
• Solid Concrete Blocks: Denser and stronger, providing better load-bearing capacity for sheds. They are less prone to absorbing moisture.
• Deck Blocks (Pier Blocks): These pre-cast concrete blocks have grooves or receptacles designed to hold deck joists or 4x4 posts, making them ideal for simple shed foundations.

Key Considerations for a Stable Block Foundation

To ensure the longevity and stability of your shed, proper preparation and execution are vital.

• Site Preparation:

  • Clear the Area: Remove all vegetation, debris, and topsoil from the shed's footprint.
  • Level the Ground: This is perhaps the most critical step. Even a slight slope can cause issues over time. Dig down high spots or build up low spots using compacted gravel or sand. A laser level or long straight edge with a spirit level is essential.
  • Gravel Base: Lay down a few inches of compacted gravel (e.g., 3/4-inch crushed stone) under each block location or across the entire footprint. This improves drainage and prevents blocks from settling unevenly.

• Block Placement:

  • Even Spacing: Place blocks at regular intervals, typically every 4-6 feet, ensuring they align with the shed's perimeter and any internal floor joists.
  • Corners and Perimeter: Always place blocks at all four corners and along the perimeter, with additional blocks supporting the center of the shed floor.
  • Shimming and Leveling: Use composite shims or pieces of pressure-treated lumber between the blocks and the shed's runners to achieve perfect levelness.

• Moisture Control and Pest Prevention:

  • Vapor Barrier: Consider laying a heavy-duty plastic sheeting (vapor barrier) over the entire footprint before placing the blocks and shed. This prevents ground moisture from rising and causing rot.
  • Perimeter Skirting: While the elevated design is good for ventilation, it can also invite pests. Consider adding a decorative skirting around the base of the shed after it's built, ensuring there's still adequate airflow.

• Local Building Codes and Permits:

  • Always check with your local municipality or county building department regarding requirements for sheds. Some areas may have size limits for structures built without a permit, or specific foundation requirements, even for small sheds. For example, some jurisdictions might require the shed to be anchored to the foundation. You can often find local regulations on municipal websites or by contacting your local planning department directly.

For more detailed guidance on shed foundations, you can consult reputable home improvement resources like The Spruce's guide on shed foundation options or Home Depot's advice on building a shed foundation.

Shed Size Guidelines for Block Foundations

Here's a quick reference for shed sizes and appropriate foundation types:

In conclusion, a block foundation is a practical and effective solution for many shed projects, provided you adhere to size limitations and ensure proper site preparation and leveling.