A backyard block wall with aloe plants, a typical shed location in Phoenix

Sizing

Shed Pad Size and Thickness

How big and how thick a concrete shed pad should be, where the anchors go, how high it should sit above the yard, and the 200 square foot line that decides whether a Phoenix shed needs a permit.

Size past the floor
4 in reinforced
Above the yard
200 sq ft permit line

Last reviewed October 2026

The short answer

Pour a shed pad about 4 inches thick, reinforced, on a compacted base, a little larger than the shed and a few inches above the yard. In Phoenix, keep a detached one-story shed at 200 square feet or less and it needs no building permit.

Shed size, pad size and the Phoenix permit line

Shed	Floor area	Pad (typical)	Phoenix permit
8x10	80 sq ft	8x10 to 9x11	Exempt
10x12	120 sq ft	10x12 to 11x13	Exempt
10x16	160 sq ft	10x16 to 11x17	Exempt
12x16	192 sq ft	12x16 to 13x17	Exempt
12x20	240 sq ft	12x20 to 13x21	Building permit

Swipe the table sideways to see every column →

Pad sizes show the range from exact footprint to about 6 in past each wall; follow the shed maker's instructions. Permit column applies to one-story detached sheds without utilities, City of Phoenix 'Work Exempt from Permit'.

Concrete placed over reinforcement for a small pad — Even a small shed pad gets reinforcement inside the slab and a compacted base under it. That is what keeps the corners level.

Getting the details right

Square the forms to the shed's exact dimensions before adding any overhang
Check the pad is level, not sloped like a patio, so the shed frame stays square
Set anchor bolts where the kit's sill plate or frame lands, or plan for post-installed anchors
Keep the pad off the block wall footing, with room to reach behind the shed
If power is going to the shed, place conduit before the pour

See concrete shed pads for prices and how the job runs.

Shed pad size and thickness: frequently asked questions

How thick should a shed slab or shed foundation be?

About 4 inches of reinforced concrete on a compacted base for most storage sheds, whether you call it a shed pad, shed slab or shed foundation. Heavier workshop sheds go thicker.

How thick should a concrete shed pad be?

About 4 inches of reinforced concrete on a compacted base suits most storage sheds. Workshop sheds with heavy machines, or sheds that hold a mower or ATV, are poured thicker.

Should a shed pad be bigger than the shed?

Usually a little, so the walls sit fully on concrete and rain drips off the slab instead of under the floor. Some shed makers want the pad exactly to the footprint so water cannot sit at the base of the wall; follow the kit's instructions.

How high above the ground should a shed pad be?

A few inches above the surrounding yard, with the ground sloping away, so monsoon runoff and irrigation flow past the shed rather than into it.

What size shed can I build without a permit in Phoenix?

A one-story detached shed of 200 square feet or less is exempt under the City of Phoenix 'Work Exempt from Permit' bulletin. Utilities to the shed need a permit. HOAs often have their own size and height limits.

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