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How to Build a Shed on a Slope: Foundation Options That Work
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Options for sloped ground
| Foundation | What This Old House says | Sloped site? | Frost-proof? |
|---|---|---|---|
| Concrete blocks | Block-and-timber is pressure-treated timber across a base of concrete blocks or pavers. It works well on slightly uneven ground and lets air flow under the shed. | Some slope OK | No |
| Deck blocks | Used to support a wooden frame. | Some slope OK | No |
| Concrete piers (pier and beam) | Concrete piers or deck blocks support a wooden frame. They suit sloped sites and poor soil, and are easy to adjust and level. | Yes | Yes |
| Post and beam | Post holes about every 4 feet, at least 12 inches below the frost line. | Yes | Yes, may need extra work |
Source: This Old House, Building a shed foundation. Table values are the article's.
Steps (from the sources)
- Pick the spot. This Old House says level and not collecting water, at least 3 feet from fences or structures. Check your town's setback rules too (see our permit guide).
- Mark the corners and find the low side. Family Handyman's project raises the low side to match the high side.
- For piers: This Old House says to set footings on flat, compacted soil at least 12 inches below the frost line, tie each footing to its pier with two lengths of No. 4 rebar, and use tubular forms set plumb on the footing to shape the piers.
- For post holes: dig holes about every 4 feet and at least 12 inches below the frost line. Pour 4 inches of crushed stone, then concrete, and wait 48 hours before filling the rest of each hole (This Old House).
- For stacked timber on the low side: Family Handyman stacks treated 2x6s, 4x6s or 6x6s on top of the 6x6 to reach the right height.
- Check for level with a level before you build the floor. This Old House's gravel base article says to use a level to adjust the frame and fill low areas.
Our note: call 811 before you dig. A gravel pad on a slope is not covered by the pages we opened; see our gravel base guide for a flat site.
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Open the shed cost calculatorCommon questions
Can you build a shed on a slope?
Yes. This Old House says block-and-timber and pier-and-beam foundations are best for uneven ground. It says pier and beam foundations suit sloped sites and poor soil, and are easy to adjust and level.
How steep is too steep?
None of the pages we opened gives a maximum slope, so we do not give one. This Old House's table marks concrete blocks and deck blocks as 'some slope OK' and concrete piers and post-and-beam as suitable for sloped sites. For a steep site, ask your local building department or a licensed pro.
Can I just stack lumber under the low side?
Family Handyman's cheap storage shed project does something like this on sloped ground: it raises the 6x6 on the low side by stacking treated 2x6s, 4x6s or 6x6s until it is level with the adjacent 6x6.
Do I need to go below the frost line?
This Old House says to set footings at least 12 inches below the frost line in freezing areas, and that some areas have specific foundation depth or type requirements. Check with your local permit office.
Where should I put a shed on a sloped yard?
This Old House says to choose a site that is level and does not collect water, at least 3 feet from fences or structures.
Related guides
Free printable: Shed Build Checklist
From permit check to the last coat of paint, in one page. Download the one-page PDF now, or get it by email along with a short series of five helpful emails.