How to Build a Shed Floor Base (10×12): Gravel, Blocks, or Concrete?

6-minute read

Sunday, February 1, 2026

A shed is only as solid as what it sits on—and any experienced shed builder in Austin will tell you the base matters as much as the shed itself. If the base is out of level or stays wet, the floor can feel bouncy, doors can stick, and your build can start to age early.

This guide covers three beginner-friendly base options for a 10×12 shed in Austin, then matches each option to either storage use or a heavier workshop setup.

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Pick the Right Shed Floor Base for Your Scenario

Option 1: Compacted Gravel Pad (Common choice for a 10×12)

Option 2: Block and Timber Base (Fast, adjustable, good on mild slopes)

Option 3: Concrete Slab (Workshop ready, most permanent)

Recommended Setup by Use Case (10×12)

Build the Floor Frame on Top of the Base

Install the Subfloor (Plywood or OSB) So It Stays Flat

Final Checks Before the Shed Goes On

Want a Shed Base That’s Level the First Time?

Frequently Asked Questions

Pick the Right Shed Floor Base for Your Scenario

Use this quick guide to narrow it down.

Your situation	Compacted gravel pad	Block and timber base	Concrete slab
Storage only (bins, yard tools)	Best fit	Good fit	Works but often extra work
Light workshop (workbench, hand tools)	Best fit with a stiffer floor	Mixed	Best fit
Heavier workshop (rolling tools, bigger equipment)	Good fit with a beefier floor	Not ideal	Best fit
Mild slope	Mixed	Good fit	Mixed
Yard that stays damp after rain	Best fit	Mixed	Works if you manage runoff

Option 1: Compacted Gravel Pad (Common choice for a 10×12)

A gravel pad is popular because it is easy to level, drains well, and can be adjusted later if the ground moves.

Materials and tools

Stakes, string, tape measure
Shovel, rake, tamper or rented plate compactor
Landscape fabric
Clean crushed stone or gravel base material
Optional: treated timbers to form a tidy border

Step by step build

Mark your pad bigger than the shed. One simple approach is to add about 1 foot in each direction beyond the shed footprint so you have room for the frame and runoff, as shown in this This Old House gravel shed foundation walkthrough.
Excavate to a consistent depth. Scrape away grass and topsoil until you reach firm ground.
Compact the soil. This helps prevent uneven settling.
Lay landscape fabric. This slows weeds and helps keep stone from mixing into the soil.
Add gravel in thin layers and compact each layer. Aim for a base that feels hard underfoot.
Check level corner to corner. Take your time here. A level pad makes every later step easier.

Austin notes

If your yard gets fast runoff during storms, build the pad so the finished surface sits slightly above the surrounding ground and keep the area around the pad clear so water can move away.

Option 2: Block and Timber Base (Fast, adjustable, good on mild slopes)

This method uses concrete blocks (or deck blocks) to support treated beams, with air space under the shed. It can work well when you need to correct a small slope and want a base you can re level later.

Two common versions

Concrete blocks with treated runners: Good for a straightforward build on fairly firm ground.
Deck blocks with beams: Helpful when you want the shed slightly elevated.

Step by step build

Lay out the footprint. Square the corners using diagonal measurements.
Plan a support grid. For a 10×12, a simple approach is rows of supports under the outer edges plus a center line of support.
Prep each block spot. Dig down a little, add gravel, and compact so each block sits on a firm mini pad.
Set blocks and level them. Use a long straight board and level to keep everything in the same plane.
Install treated beams or runners. Recheck level and square before you build the floor frame.

A common detail with this style is placing masonry blocks on a gravel base. Lowe’s notes that one on grade option is masonry blocks set on a 4 inch gravel base, which is a good starting point for your block pads (see Lowe’s shed foundation guide).

A practical limit to know

Blocks can work for storage sheds and light workshops, but if you plan to load the shed like a real shop, a gravel pad with a stiffer floor frame or a slab tends to feel more solid.

Option 3: Concrete Slab (Workshop ready, most permanent)

A slab is the most permanent choice and is a strong option for heavier workshop use. If you go this route, plan for careful prep so the slab has a stable base.

Slab basics to keep simple

Forms hold the shape.
A compacted gravel layer under the slab helps drainage and stability.
Proper finishing and curing help the surface last.

If you are estimating materials, the QUIKRETE calculator is built to estimate bag counts for a slab and lets you compare a 4 inch versus 6 inch thickness (use the QUIKRETE concrete calculator to run both numbers).

Step by step overview

Layout and form the pad. Use straight forms, stake them well, and confirm square.
Excavate and add a compacted gravel base. The slab is only as good as what is below it.
Pour, screed, and finish. Work in a steady flow so you do not end up with high and low spots.
Cure. Protect the slab from drying too fast, especially in sun and wind.

Recommended Setup by Use Case (10×12)

Recommended Setup by Use Case visual selection

Storage only

Best pick: Compacted gravel pad.
Floor pairing: Standard treated runners and a solid subfloor.

Light workshop

Best pick: Gravel pad or concrete slab.
Floor pairing: Closer joist spacing and a thicker subfloor so the floor feels steady under a workbench.

Heavier workshop

Best pick: Concrete slab.
Floor pairing: If you are building a wood floor system, go heavier on framing and subfloor to reduce bounce.

Build the Floor Frame on Top of the Base

No matter which base you choose, your floor frame is what makes the shed feel strong.

Skids vs perimeter frame

Skids (runners): Great on gravel pads and blocks. They spread load and make alignment easier.
Full perimeter frame: Helpful when you want the floor frame itself to be the rigid box that stays square.

Joist spacing that feels solid

A simple rule is that tighter spacing feels stiffer. For a workshop shed, closer joists plus blocking reduces bounce and makes the floor feel more like a room than a platform.

Use treated lumber near the ground

Parts that sit close to soil or get splashed need the right treatment level. AWPA’s Use Category System explains exposure levels like above ground exterior versus ground contact, which helps you choose lumber rated for the conditions it will live in (see the AWPA Standard U1 excerpt).

Install the Subfloor (Plywood or OSB) So It Stays Flat

For a shed, your goal is a flat, stiff deck that does not flex under load.

Panel type: Tongue and groove is a nice upgrade because it supports long edges.
Fastening: Use construction adhesive on joists plus nails or screws.
Layout: Stagger seams and leave a small gap at panel edges.

APA explains that span ratings stamped on panels relate to support spacing, and that tongue and groove edges can remove the need for blocking along long panel edges in many floor builds (see APA’s Underlayment and subfloor guidance).

Final Checks Before the Shed Goes On

Level: Check in both directions and corner to corner.
Square: Measure diagonals. If they match, you are square.
Drainage: Make sure water can move away from the base.
Walk test: If it feels soft now, it will feel softer when loaded.

Want a Shed Base That’s Level the First Time?

If you are working on a sloped yard, dealing with soft spots, or planning a workshop style shed that needs to feel rock solid, it can help to have a crew handle the prep and build details. Small House Solutions builds backyard structures in Austin and can help you get a clean, durable setup from base prep through the finished shed. Learn more on our Shed Builder Austin page.

Frequently Asked Questions

1) How deep does a gravel base need to be for a 10×12 shed?

It depends on how soft your soil is and how much you plan to store. A good approach is to excavate until you reach firm ground, then build up gravel in thin compacted layers until the pad is level and feels hard underfoot.

2) Can I put a shed directly on gravel without a wood frame?

You can, but most DIY builds are easier if the shed sits on skids or a floor frame that spreads load. A simple frame also makes it easier to square the shed and keeps the floor system consistent.

3) What floor framing works for a workshop shed?

Aim for a stiffer floor than you would use for basic storage. Use closer joist spacing, add blocking, and choose a thicker subfloor so the floor feels steady under a workbench and heavier tools.

4) What is the fastest base option for a first time DIY build?

A block and timber base can be quick on a mild slope, and it is easy to adjust. If your yard is flat and you want a forgiving option, a compacted gravel pad is often a smooth path.

5) How do I keep the shed floor from trapping moisture?

Start with drainage around the base and avoid letting soil or mulch touch the floor frame. Using treated lumber rated for close to ground exposure and leaving air space under the shed also helps the floor dry out after rain.

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