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Can You Put a Shed on Concrete Blocks? What Works and What Doesn't
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What the sources say
| Foundation (This Old House) | Slope | Frost-proof |
|---|---|---|
| Concrete blocks (block and timber) | Some slope OK | No |
| Deck blocks | Some slope OK | No |
| Concrete piers | Yes | Yes |
| Post and beam | Yes | Yes, may need extra work |
Source: This Old House, Building a shed foundation (table values are the article's).
- Good points (This Old House): block-and-timber is pressure-treated timber across a base of concrete blocks or pavers. It works well on slightly uneven ground and allows air to flow under the shed.
- Warning (Family Handyman): setting a shed on a few concrete blocks will cause problems down the road when the ground freezes, thaws and settles differently.
- Frost (This Old House): freezing areas need frost-resistant options, and some areas have specific foundation depth or type requirements. Check with your local permit office.
- Soil (This Old House): clay soils expand and contract as moisture changes. Sandy soils may need reinforcement.
The pages we opened do not give a block spacing, a maximum block size or a load limit, so we do not either. Our shed foundation guide compares all the options.
Steps before you set the first block
- Ask your building department about frost depth, the foundation type your town wants and whether the shed needs a permit.
- Pick a level spot that does not collect water, at least 3 feet from fences or structures (This Old House).
- Plan the anchoring. See how to anchor a shed.
- Consider piers if the ground freezes or slopes. See shed on a slope.
What will your shed cost?
Our free calculator compares building it yourself, buying a kit and hiring a builder for your exact size.
Open the shed cost calculatorCommon questions
Can you put a shed on concrete blocks?
Yes, for many sheds. This Old House describes block-and-timber foundations, with pressure-treated timber resting on concrete blocks or pavers, as working well on slightly uneven ground and letting air flow under the shed. It also lists deck blocks. Both are marked 'No' for frost-proof.
What goes wrong with blocks?
Family Handyman lists setting a shed on a few concrete blocks among shed-building mistakes. It says this will cause problems down the road when the ground freezes, thaws and settles differently. This Old House says freezing areas need frost-resistant options and that some areas have specific foundation depth or type requirements.
Do blocks work on a slope?
This Old House's table marks concrete blocks and deck blocks 'some slope OK', and says block-and-timber is best for uneven ground. Piers and post-and-beam are marked as suited to sloped sites.
Do I need to anchor a shed on blocks?
Possibly. Sioux Falls says a shed simply placed on the ground must be anchored at each corner, and Hopkins, Minnesota says all corners must be anchored to a slab or by in-ground anchors. Ask your building department.
Can a permit-free shed sit on pier blocks?
In Seattle, yes: the page lists a shed that sits on a concrete slab, pier blocks or soil among the conditions for needing no permit, along with a 120 square foot roof footprint, one story, not attached to a building, not near an environmentally critical area and used only for storage or similar. Other cities differ.
Related guides
- This Old House: Building a shed foundation
- Family Handyman: 15 Shed Building Mistakes and How to Avoid Them
- City of Sioux Falls, SD, Building Services: Anchoring of Storage Buildings Requirements (handout dated March 2010)
- City of Hopkins, MN: Building a Shed
- Seattle Department of Construction and Inspections: Sheds
Free printable: Shed Build Checklist
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