DIY Guide to Building Concrete Footings for Outdoor Sheds

Building a sturdy and lasting outdoor shed requires a solid foundation. One of the most reliable and durable foundations for sheds is concrete footings. These footings provide a stable base to prevent shifting, sinking, or tilting over time. Whether you’re building a small garden shed or a larger storage structure, understanding how to properly build concrete footings is essential.

In this comprehensive guide, we’ll walk you through everything you need to know about constructing concrete footings for outdoor sheds. From planning and materials to pouring and curing, you’ll gain the confidence to tackle this project yourself.

Why Concrete Footings Are Important for Outdoor Sheds

Concrete footings serve several critical functions:

• Stability: They distribute the weight of the shed evenly into the ground, reducing the risk of uneven settling.
• Durability: Concrete resists moisture, decay, and pest damage better than wood alone.
• Level Base: Footings help create a level surface necessary for proper shed assembly.
• Frost Protection: In cold climates, footings that extend below the frost line prevent shifting caused by freeze-thaw cycles.

Without proper footings, your shed may become unstable, leading to structural damage or collapse.

Planning Your Shed Footings

Determine Footing Size and Depth

The size and depth of your concrete footings depend on several factors:

• Shed size and weight: Larger sheds require larger and deeper footings.
• Soil type: Sandy, loose soil needs deeper footings than compacted clay soil.
• Climate: Areas with freezing temperatures require footings to be below frost depth (typically 12–36 inches).
• Local building codes: Always check with your municipality for specific requirements.

As a general rule of thumb:

• Footing width: At least 12 inches wide.
• Footing depth: At least 12 inches deep or below frost line.
• Thickness: Typically 6–8 inches for shed footings.

Choose Your Footing Type

There are common footing types used for sheds:

1. Concrete Pier Footings: Individual columns poured at each support point.
2. Continuous Strip Footings: Long strips of concrete running under load-bearing walls.
3. Slab-on-Grade: A full concrete slab supporting the entire shed floor.

Pier footings are popular for small-to-medium sheds because they use less concrete and provide strong localized support.

Layout and Marking

1. Measure your shed footprint accurately.
2. Mark the location of each footing according to your shed plans.
3. Use stakes and string lines to outline the perimeter and footing spots.
4. Double-check diagonals to ensure squareness.

Materials and Tools Needed

Materials

• Concrete mix (premixed bags or ready-mix truck delivery)
• Gravel or crushed stone (for base)
• Wooden stakes
• Rebar or wire mesh (optional reinforcement)
• Form boards (usually 2x4s or similar)
• Plastic sheeting or curing blanket (optional)

Tools

• Shovel or post hole digger
• Tape measure
• Level
• Hammer and nails or screws
• Wheelbarrow or mixing tub (if mixing concrete yourself)
• Trowel or float
• Concrete vibrator (optional)
• Safety gear: gloves, goggles, dust mask

Step-by-Step Instructions for Building Concrete Footings

Step 1: Excavate Holes for Footings

Using a shovel or post hole digger, excavate holes where each footing will go:

• The diameter should be about twice the width of your footing form (e.g., 24 inches for a 12-inch footing).
• The depth should meet local frost line requirements or at least 12 inches deep.

Remove all loose soil from the bottom; compact if possible.

Step 2: Prepare the Base with Gravel

Add 3–4 inches of gravel or crushed stone to the bottom of each hole:

• This promotes drainage and prevents water pooling under your footing.
• Tamp it down firmly with a tamper or the flat side of your shovel handle.

Step 3: Build Forms Around Each Hole

Create forms using wooden boards to hold wet concrete in place:

• Cut boards to create a circular form slightly larger than the intended footing diameter.
• Secure boards with stakes driven into surrounding soil.
• Ensure forms are level and plumb vertically.

For continuous strip footings, build long rectangular forms instead.

Step 4: Add Reinforcement (Optional but Recommended)

For extra strength:

• Place rebar inside each footing hole in a grid pattern.
• Alternatively, use wire mesh laid inside forms.

Tie rebar together with wire ties so it stays in place during concrete pouring.

Step 5: Mix and Pour Concrete

If using bagged concrete mix:

1. Follow manufacturer’s instructions mixing water and dry mix in wheelbarrow or mixing tub.
2. Mix thoroughly until smooth consistency is achieved without lumps.

Pour concrete into forms slowly:

• Fill each form completely.
• Use a shovel or trowel to spread concrete evenly.

Step 6: Remove Air Bubbles and Level Surface

After pouring:

• Use a concrete vibrator or tap sides of forms gently with hammer to release trapped air bubbles.
• Screed surface with a straight edge (board) across top of form for level finish.

Use trowel or float to smooth top surface as needed.

Step 7: Cure the Concrete Properly

Curing is critical for strength development:

1. Cover freshly poured footings with plastic sheeting or wet burlap to retain moisture.
2. Keep covered and moist for at least 3 days—ideally up to 7 days.
3. Avoid walking on or disturbing forms during this time.

Proper curing reduces cracking and maximizes durability.

Step 8: Remove Forms and Backfill

Once cured sufficiently:

1. Carefully remove wooden forms without damaging edges.
2. Backfill around footings with soil; tamp firmly to reduce settling near footings.

Your concrete footings are now ready!

Additional Tips for Success

Check Local Regulations Early

Always consult local building codes before starting. You may need permits or inspections depending on your area’s requirements.

Use Quality Materials

Invest in good-quality concrete mix designed for outdoor/structural use. Fresh gravel base ensures better drainage.

Protect Yourself

Wear gloves and eye protection when handling cement as it can irritate skin and eyes.

Consider Hiring Help for Large Sheds

Large sheds may require multiple cubic yards of concrete—consider professional help if unsure.

Plan Drainage Around Shed Site

Ensure water runs away from your shed foundation by grading site properly after construction.

Conclusion

Building concrete footings for an outdoor shed may seem daunting initially, but breaking it down into clear steps makes it manageable even for DIY enthusiasts. Solid footings ensure your shed will stand firm through weather changes, soil movement, and time itself. By carefully planning, measuring, digging, pouring, and curing your footings correctly, you provide your shed with a reliable foundation that will protect your investment for years to come.

With patience and attention to detail, you can confidently build your own concrete footing foundation—and enjoy the satisfaction of completing another rewarding outdoor project!