Ag-Exempt Farm Buildings in SLO & Santa Barbara Counties

Steel frame or wood posts?

In general terms, a steel building uses a steel frame, often pre-engineered for the site, on a concrete slab or footings. A pole barn (post-frame building) uses wood posts, usually set in the ground or on footings, with wood or metal framing between them. Steel frames don’t rot and aren’t eaten by pests; wood posts are familiar and easy to modify. The right choice depends on what the building will hold, how big it needs to be, your budget and local rules, and either way the permit questions below are the same.

Is there a farm building exemption?

Both counties here exempt certain agricultural buildings from a building permit, with conditions. An exemption is never a free pass: zoning, setbacks, electrical and plumbing permits and grading rules still apply.

San Luis Obispo County

The exemption is in County Code §19.02.020, for “Agricultural accessory buildings that meet all of the following criteria.” Among them:

Use: “A structure designed and constructed to house farm implements, hay, grain, poultry, livestock or other horticultural products.” It can’t be a home, a place where products are processed or packaged, or a place used by the public.
Land: in an Agriculture or Rural Lands land use category, outside urban and village reserve lines, and “The property size is 20 acres or more.”
Setbacks: more than 100 feet from any adjacent property or public road, and 50 feet from other structures.
Size: “The floor area does not exceed 3,000 square feet and building height does not exceed one story including storage loft/mezzanine (⅓ of the ground floor area) open to floor below.”
Utilities: no plumbing fixtures other than hose bibbs, wash sinks or lavatories, and only the lighting and wiring the use needs, each “installed with a separate permit.” No insulation, heating or cooling unless needed to store certain farm products.
Not covered: buildings in an Airport Review, Flood Hazard or Sensitive Resource Area combining designation.

The county’s application form (BLD-1001, 01/12/2026) adds:

“THIS EXEMPTION IS NOT APPLICABLE TO STRUCTURES USED FOR GROWING, INCLUDING BUT NOT LIMITED TO GREENHOUSES AND HOOP STRUCTURES.”
“Agricultural buildings within the Coastal Zone are NOT exempt from the provisions of the Coastal Zone Land Use Ordinance (CZLUO).”
“The proposed structure must comply with the structural provisions of the 2025 California Building Code.”
“Unless otherwise exempted, separate plumbing, electrical, and mechanical permits will be required for the Ag-exempt building.”

The county’s Agricultural Exempt Building page notes that approval “only entitles the use itself; separate permits may also be required for any construction or grading activities,” and points to the county fee schedule for fees. The county code also exempts small open-sided animal shade covers under its own limits.

Santa Barbara County

The county’s building code (Chapter 10, Sec. 10-1.6.1) exempts “Agricultural buildings not exceeding 3,000 square feet in floor area constructed and used to house farm implements, equipment, hay, grain, poultry, livestock or horticultural products.” The conditions:

Use: they “shall not be a place of human habitation nor a place of employment,” can’t be used by the public, and can’t have features that change the building’s occupancy, as determined by the Building Official.
Zoning and a land use permit: they “shall be located on agriculturally or residential ranchette zoned land and receive a land use permit from the Planning and Development Department.”
Separation: “A minimum 20-foot separation shall be maintained between such buildings and other buildings and property lines.”
Trade permits still apply: the exemption does not exempt the building “from electrical, plumbing, or mechanical permits and their associated fees.”

Start with the county’s Permitting & Enforcement page, or call Planning and Development before you order a building.

Inside cities and on smaller lots

These exemptions are for unincorporated county land that meets the conditions above. In a city, or on a lot that doesn’t qualify, a barn, shop or storage building generally needs a regular building permit. See Do I need a building permit? and check with that city’s building department.

Checking the builder’s license

CSLB describes a B general building contractor as one whose work involves structures “requiring in its construction the use of at least two unrelated building trades or crafts” (CSLB), and a C-51 structural steel contractor as one who “fabricates and erects structural steel shapes and plates” (CSLB). Whoever you hire, check the license on the CSLB site. Our guide on hiring a licensed contractor covers what else to check.

What affects the cost

Size, height and roof span; the foundation and site work; doors and openings; and whether the building needs power, water or insulation. An exempt building can still need engineered plans and separate trade permits. See our steel building page for how a project usually goes.

Steel building or pole barn? Farm building permits on the Central Coast