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Concrete Slabs & Foundations in Sacramento, CA

Quick answer

Shed and equipment pads are usually reinforced slabs over compacted aggregate, while workshops, garages, ADUs and additions need thicker slabs and footings designed to the California building code, with permits and inspections. Expansive clay, hardpan or foothill granite can change the design and cost. Contact USA North 811 before digging.

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Sheds, workshops, detached garages, patio covers, hot tubs, accessory dwelling units (ADUs) and room additions all need something solid to sit on. For a small shed, that might be a simple slab. For anything people will live in, or anything attached to the house, it means footings and a foundation designed to the California building code, with a permit and inspections.

Common slab and foundation projects

  • Pads for storage sheds, playhouses and garden buildings
  • Slabs for workshops, detached garages and carports
  • Pads for hot tubs, HVAC equipment, generators and battery or EV equipment
  • Foundations for ADUs, room additions and sunrooms

Small structures and pads

A shed or equipment pad is usually a reinforced slab over compacted aggregate, sometimes with a thickened edge. Size it to the building plus a little extra, keep it level for the structure while letting the edges shed water, and confirm setbacks from property lines, easements and the house. Cities and counties around Sacramento set their own size limits for when an accessory structure needs a permit, and HOAs often have rules of their own, so check before you pour.

ADUs, additions and structural work

California has encouraged ADUs in recent years, and many Sacramento-area homeowners are adding them in backyards. Their foundations, like those for additions, carry the building's load and must follow the California Residential Code as adopted locally. Expect a building permit, plans (often engineered), footing inspections before the pour, and sometimes a soils report. Concrete subcontractors commonly pour these foundations under a general contractor who holds the permit, so make sure everyone's role is clear.

Sacramento-area soil and site factors

  • Expansive clay: where soils shrink and swell, engineers may call for deeper footings, a moisture barrier or a post-tensioned slab design.
  • Hardpan: a cemented layer near the surface can be hard to dig through and can trap water. Your contractor may need heavier equipment, and drainage needs extra thought.
  • Granite in the foothills: in parts of Rocklin, Folsom and the surrounding foothills, rock close to the surface can affect excavation and cost.
  • Floodplains: some low-lying parts of the region are in mapped flood zones, which can affect how high a new floor must sit. Ask your building department.
  • Utilities: California law requires contacting USA North 811 at least two working days before digging so underground lines can be marked.

Licensing

In California, any job of $1,000 or more in labor and materials, or any job that needs a permit, requires a CSLB-licensed contractor. Concrete contractors usually hold the C-8 classification; ADUs and additions are generally run by a licensed general building contractor. Check licenses on the CSLB website.

Questions to ask

  • Does this need a permit, and who will pull it?
  • How thick is the slab, and what reinforcement, base and vapor retarder are included?
  • Is a soils report or engineered foundation needed for this lot?
  • What do you need from the shed, ADU or addition builder before you start?

Planning a building? Request a slab or foundation contractor and include the structure's size and use.

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How a concrete mixer truck delivers a pour. Press the buttons to run each step and see what happens inside. Made with Colorfigures ·
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Frequently asked questions

Do I need a permit for a shed slab in the Sacramento area?

It depends on your city or county and the size of the structure. Many set a size above which an accessory building needs a permit, and setbacks and HOA rules also apply. Check with your building department before pouring.

Can an unlicensed handyman pour my shed slab?

Only if the job is under $1,000 in labor and materials, needs no permit, and the person works alone with no employees. That has been California's minor work exemption since January 1, 2025. Above that, use a CSLB-licensed contractor.

What does an ADU foundation involve?

A building permit, plans that are often engineered, footing inspections before the pour, and sometimes a soils report. The concrete work is commonly done under a licensed general contractor who holds the permit.

Sources and further reading

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