Work That Does Not Need a Building Permit: IRC R105.2 Exemptions

The Starting Point: Permits Are the Default

Section R105.1 of the 2021 IRC says that any owner or contractor who intends to construct, enlarge, alter, repair, move, demolish or change the occupancy of a building, or to install or change any electrical, gas, mechanical or plumbing system regulated by the code, must first apply to the building official and get a permit. That wording matters: the exemptions in R105.2 are exceptions to a general rule, so anything not on the list is presumed to need a permit unless your local code says otherwise.

R105.2 also contains an important sentence that people often miss. Exemption from the permit requirement does not authorize work that violates the code or any other local law. A fence that does not need a building permit must still meet zoning height limits, and an exempt shed must still respect setbacks.

Building Work the IRC Exempts

The building part of R105.2 lists these items for one- and two-family dwellings and townhouses:

• Accessory structures: one-story detached buildings such as tool sheds, playhouses and similar uses, with a floor area of 200 sq ft or less.
• Fences not over 7 ft high.
• Retaining walls not over 4 ft high, measured from the bottom of the footing to the top of the wall, unless they support a surcharge.
• Water tanks supported directly on grade with limited capacity and proportions.
• Sidewalks and driveways.
• Finish work: painting, papering, tiling, carpeting, cabinets, countertops and similar work.
• Prefabricated swimming pools less than 24 inches deep.
• Swings and other playground equipment.
• Window awnings supported by an exterior wall that project no more than 54 inches and need no extra support.
• Decks not exceeding 200 sq ft, not more than 30 inches above grade at any point, not attached to the dwelling and not serving the required exit door.

Notice how narrow some of these are. The deck exemption fails if any one condition fails: a 150 sq ft deck that is bolted to the house, or one that is 32 inches off the ground at its low corner, needs a permit under the model code.

Electrical, Gas, Mechanical and Plumbing Exemptions

The trade exemptions in R105.2 are about repairs and portable equipment, not replacements:

• Electrical: listed cord-and-plug equipment, repairs and maintenance of appliances, and electrical equipment used for radio and television transmission, within limits.
• Gas: portable heating, cooking or clothes-drying appliances; replacement of any minor part that does not alter approval of the equipment or make it unsafe; and portable fuel cell appliances.
• Mechanical: portable heating appliances, portable ventilation appliances, portable cooling units, steam and hot-water piping within listed equipment, replacement of minor parts, self-contained refrigeration systems with limited refrigerant, and portable evaporative coolers.
• Plumbing: stopping leaks in drains, water, soil, waste or vent pipe (unless concealed piping has to be removed and replaced), and clearing stoppages or repairing leaks in pipes, valves or fixtures, as long as the repair does not replace or rearrange valves, pipes or fixtures.

The pattern is clear: repairing something is often exempt, while replacing a whole system is not. That is why a furnace or air-conditioner replacement needs a permit in most of the cities we track, as HVAC Replacement Permit Rules in 10 US Cities shows.

R105.2.1 adds a practical rule for emergencies: where equipment replacement or repair must be done urgently, the permit application can be submitted within the next working business day. R105.2.2 says ordinary repairs need no permit, but repairs cannot include cutting away a wall, removing structural supports or changing egress, and they cannot include adding to or rearranging plumbing, gas or electrical systems.

How Cities Rewrite the List

Cities publish their own exemption lists, and they are worth reading line by line.

Austin, Texas

Austin's Development Services Department page on work exempt from building permits mirrors much of the IRC: detached accessory structures of 200 sq ft or less and no more than 15 ft tall, fences up to 7 ft outside a flood hazard area, retaining walls up to 4 ft, and decks of 200 sq ft or less, no more than 30 inches high and not attached. Austin adds its own items: repairs to gypsum board, foundations and floor decking of 128 sq ft or less; like-for-like asphalt shingle replacement unless the home is in the Wildland-Urban Interface and 50% or more of the roof is replaced; exterior trim; siding up to 128 sq ft; roof decking up to 128 sq ft; garage doors; and replacing doors of the same size and operation. Replacing fixtures, faucets and exposed traps is exempt, but a new or replacement shower or tub is not.

Nashville, Tennessee

Metro Nashville Codes publishes a list of projects that may or may not require a permit for one- and two-family homes. It says no permit is needed for furnace repairs, glass replacement, storm windows, skylight replacement, door replacement that does not change the opening, fences (which must still meet zoning), and pergolas or trellises. It does require permits for windows that change style or size, new skylights, siding repair over 100 sq ft, drywall over 100 sq ft, decks, adding a roof layer or replacing more than a third of the roof, structural or roof-decking work over 64 sq ft, patios more than 6 inches above grade, pools, and an increase in electrical service. Solar is listed as needing an electrical permit only.

Philadelphia, Pennsylvania

Philadelphia's Start Right guide (June 2026) says replacing windows and doors in existing openings on one- and two-family homes needs no building permit, that sheds under 130 sq ft in a rear yard need no zoning permit, and that a one-story detached structure under 200 sq ft is exempt from a building permit. Non-masonry fences under 6 ft and minor plumbing and electrical repairs are also listed as exempt.

Exempt from a Permit Is Not Exempt from the Rules

Three kinds of rules still apply to exempt work.

1. Zoning. Height limits, setbacks, lot coverage and the number of accessory buildings come from the zoning code, not the building code. Nashville's list says this directly for fences.
2. Special districts. Historic districts, floodplains and wildfire zones often need their own approval. Austin's fence exemption, for example, does not apply in a flood hazard area.
3. Private rules. HOA covenants and deed restrictions are enforced separately and can be stricter than the city.

A Quick Decision Checklist

Before starting a project, run through these questions:

1. Is the work on your city's exemption list, with every size and height condition met?
2. Does it touch structure, egress (exit doors and windows), or the electrical, gas, mechanical or plumbing systems beyond a simple repair?
3. Is the property in a historic district, floodplain or wildfire zone?
4. Does zoning limit the height, size or location?
5. Would you be comfortable explaining the work to a future buyer's inspector?

If any answer gives you pause, call the permit office. For what is at stake if you guess wrong, see What Happens If You Build Without a Permit?.

Building Departments in the Cities We Cover

Rules in this guide vary by jurisdiction. These are the official departments that issue residential permits in the ten cities we track, with the city's open-data source for permit records. Each city page shows the rules for roofing, HVAC, solar, fence and deck work.

Before relying on any rule, read the department's current page or call its permit desk. Model-code sections cited here (such as IRC R105) are adopted locally, often with amendments.

Frequently Asked Questions