Concrete Shed Pad Cost and Construction Guide (4″ Slab vs Gravel)

Quick answer: a 4-inch concrete shed pad costs about $700 to $1,190 installed for an 8x10 shed, $970 to $1,680 for a 10x12 and $1,450 to $2,560 for a 12x16. DIY materials run about $460 to $650 for a 10x12. A compacted gravel pad for the same 10x12 shed costs only about $60 to $140 in stone, but it is a different kind of foundation.

Whether a shed needs concrete at all depends on what goes in it and what kind of shed it is. A wood shed with its own floor frame sits happily on gravel. A shed with no floor, a workshop, or anything storing a mower, tractor or heavy tools is better on a slab. This guide prices both, then covers how to build the slab so the shed stays square, dry and anchored.

Concrete Shed Pad Cost by Size

Small pads cost more per square foot than big slabs because the delivery fee, setup and a contractor's minimum charge are spread over less area. Some contractors price shed pads as a flat job. Four inches is right for most sheds; use 5 inches if you will drive a riding mower or ATV in and out every week. Try other sizes in the slab cost calculator or on the shed pad page.

Concrete Slab vs. Gravel Pad

A gravel pad is a layer of compacted crushed stone held in by a timber or block border. Here is how the costs compare. Gravel figures are compacted stone at 4 or 6 inches deep, with excavation added for the installed price. The timber or block border is extra.

A 10x12 gravel pad at 4 inches needs about 1.70 yd³ of stone (about 2.4 tons). Many builders also extend a gravel pad past the shed on each side so roof runoff does not splash mud onto the siding. Use the gravel base calculator for your size.

How to Build a Concrete Shed Pad

1. Check the rules first. Call 811 before digging, and check setbacks from property lines (see permits below).
2. Size the slab to the shed. For a shed built on the slab, make the slab the same size as the wall frame, or a touch smaller, so the siding laps over the edge and sheds water outside the slab. A slab that sticks out past the walls catches rain and channels it under the sill.
3. Dig and build the base. Strip sod and soft soil, then place and compact a 4-inch gravel base. On a 10x12 that is about 1.70 yd³ of stone. Excavation and base together run about $1.40 to $3.30 per sq ft if you hire it out.
4. Set forms. 2x4 forms for a 4-inch slab, staked every 3 to 4 ft, with the top about an inch or two above grade so the sill stays out of splash and wet soil. Slope the top slightly toward the door or to one side so any water inside can drain out.
5. Add vapor barrier and reinforcement. 6-mil plastic under the slab keeps ground moisture out of stored items; on a 10x12 it costs about $30 to $54. Welded wire mesh on chairs is usually enough for a shed, or #4 rebar for heavy loads.
6. Pour, finish and joint. A 10x12 needs 1.63 yd³: 74 bags of 80-lb mix or a small ready-mix load. Joints should be no more than about 12 ft apart, so one joint across the middle is enough on most shed pads.
7. Set anchors and cure. Press anchor bolts into the wet concrete along the wall lines, then keep the slab damp or covered while it cures. Walk on it after 24 to 48 hours; wait about 7 days before building on it and longer before heavy loads.

Anchoring and Thickened Edges

For a site-built shed, anchor bolts set in the slab hold the bottom plate down. IRC R403.1.6 calls for 1/2-inch bolts no more than 6 ft apart and within 12 inches of each plate end for houses, and many shed plans use the same layout. For a prefab shed, follow the maker's anchoring kit; many use concrete wedge or screw anchors drilled after the slab cures. In high-wind or hurricane areas your town may require a specific tie-down.

A thickened edge (a turn-down about 12 inches wide and 12 inches deep around the perimeter) stiffens the slab edge where the walls bear and resists frost undermining the edge. On a 12x16 pad it adds about 1.41 yd³ of concrete, roughly $210 in ready-mix plus some extra digging. It is a good idea on larger sheds and workshops, and some building departments require it once a permit is involved. The footing calculator sizes it.

Do You Need a Permit?

The IRC (section R105.2) exempts one-story detached accessory buildings up to 200 sq ft from a building permit, so an 8x10, 10x12 or 12x16 shed often needs none, while a 12x20 (240 sq ft) usually does. Many towns change that limit, and zoning setbacks, easements and HOA rules apply even when no permit is needed. Where a permit is required, small slab permits typically cost $50 to $350. For frost, IRC R403.1.4.1 lets a detached light-frame accessory building of 600 sq ft or less sit on a slab without frost-depth footings. See do you need a permit for a concrete slab.

Bags or Ready-Mix?

Shed pads sit right on the line. Below about 1 cubic yard, bags usually win; above about 1.5 yards, a truck usually wins. An 8x10 (1.09 yd³, 49 bags) is in between, and most DIYers do it with bags, a rented mixer and two helpers. A 10x12 or larger is easier with ready-mix, but expect a short-load fee of about $80 to $200 on small orders. Our ready-mix vs. bagged guide walks through the break-even.

DIY or Hire a Pro?

A shed pad is one of the best concrete jobs to do yourself. It is small, it does not need a decorative finish, and the main skill is getting the forms square and level. Hire out if the site needs real excavation, the truck cannot reach, or the shed is a large workshop that needs a permit and inspection. If you get a bid, check it with the concrete quote checker.

Sources and Method

Concrete prices use the same line items as our calculator; gravel pad prices use our gravel, compaction and excavation rates (see our methodology). Local prices vary. Code references: IRC R105.2 (work exempt from permit), IRC R403.1.4.1 (frost protection exemption), IRC R403.1.6 (anchor bolts) and IRC R506 (slabs on ground), with ACI 302.1R for slab construction. Your local building department has the final say.