You need a building permit for most work that adds, alters or demolishes a structure, or that changes electrical, plumbing, gas or mechanical systems. Cosmetic work usually doesn’t need one. The tricky part is the middle ground: small sheds, low decks, fences and minor repairs, where the answer depends on size, height and your local rules. This guide goes project by project so you can find the likely answer, then shows how to confirm it for your address.
Quick answer: You generally need a building permit for new structures, additions, structural changes, decks attached to the house or more than 30 inches above grade, most pools, and new or changed electrical, plumbing and HVAC work. Painting, flooring, cabinets and similar finish work are usually exempt. Many codes also exempt small detached sheds (often up to 200 sq ft) and fences up to 7 feet, though zoning rules still apply.
Key takeaways
- Most U.S. jurisdictions base their rules on the International Residential Code (IRC), then amend it locally.
- Exemption from a building permit doesn’t mean exemption from zoning, HOA or electrical rules.
- Size, height and attachment to the house are the usual tipping points.
- Your local building department has the final word; ask before you build.
- Work done without a required permit can cause problems at sale, with insurance and with fines.
What a building permit is and why it exists
A building permit is written permission from your city or county to carry out construction work. It has two halves. Before work starts, a reviewer checks your drawings against the building code and zoning rules. During and after the work, an inspector visits the site to confirm it was built as approved. The process exists to make sure structures are safe to live in and around, that they won’t harm neighbouring properties, and that a future owner can trust what is behind the walls.
Permits are also a record. Once the final inspection passes, the work is documented in the property file, which matters when you sell, refinance or make an insurance claim.
Who decides whether you need a building permit
Permits are issued locally. Inside city limits, the city building department handles them; in unincorporated areas, it is usually the county. Most states adopt a version of the International Residential Code for one- and two-family homes, and local governments then add their own amendments. Some states, such as New York and New Jersey, have a statewide code, while others leave more to local choice. The result is that two neighbouring towns can treat the same shed differently.
Our state pages list how permits are handled in each state, and our guide on how to apply for a building permit walks through the process once you know you need one.
Work usually exempt under the residential code
Section R105.2 of the IRC lists work that doesn’t need a building permit. Local codes often keep this list, sometimes with changes. In the model code, exempt work includes:
- One-storey detached accessory structures, such as tool sheds and playhouses, with a floor area not over 200 sq ft.
- Fences not over 7 feet high.
- Retaining walls not over 4 feet high, measured from the bottom of the footing to the top of the wall, unless they support a surcharge such as a driveway or slope.
- Water tanks on grade up to 5,000 gallons with limited height-to-width ratios.
- Sidewalks and driveways.
- Painting, papering, tiling, carpeting, cabinets, countertops and similar finish work.
- Prefabricated 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.
- Decks not over 200 sq ft, not more than 30 inches above grade, not attached to the house and not serving an exit door.
Two cautions. First, many cities lower these thresholds; 120 sq ft for sheds is common, and some require permits for any fence. Second, building permit exemptions don’t cover electrical, plumbing or mechanical work, so a shed with a light circuit still needs an electrical permit.
Do I need a building permit? Project by project
| Project | Building permit usually needed? | Key triggers |
|---|---|---|
| Deck | Usually | Attached to the house, over 30 in. above grade, over 200 sq ft, serves an exit door |
| Fence | Sometimes | Over 7 ft (model code); many cities require a zoning permit for any fence |
| Shed | Sometimes | Over 200 sq ft (often 120), electricity, plumbing, or permanent foundation |
| Detached garage | Yes | Almost always over the shed exemption size |
| Carport | Usually | Roofed structure; size and attachment matter |
| In-ground pool | Yes | Plus barrier, electrical and often zoning review |
| Above-ground pool | Usually | 24 in. deep or more |
| Hot tub | Usually | Electrical permit at minimum; barrier or cover rules |
| Home addition | Yes | Always |
| ADU | Yes | Always, plus zoning approval |
| Kitchen or bath remodel | Often | Moving plumbing, new circuits, removing walls |
| Removing a wall | Yes if load-bearing | Structural change |
| Roof replacement | Often | Many places require a permit for reroofing; repairs may be exempt |
| Window replacement | Sometimes | Changing opening size, egress or energy rules |
| Water heater | Usually | Plumbing and gas or electrical work |
| Solar panels | Yes | Building and electrical review |
| EV charger | Usually | New circuit and electrical permit |
| Driveway | Sometimes | New curb cut, widening, impervious surface limits |
| Retaining wall | Over 4 ft or surcharged | Height from the bottom of the footing; loads above |
| Painting, flooring, cabinets | No | Finish work |
For the projects people ask about most, we have dedicated guides: deck permits, fence permits, shed permits, pool permits, garage permits and home addition permits.
Electrical, plumbing and mechanical permits
Trade permits are separate from the building permit and are often needed even when the building work is exempt. In general, expect a permit for:
- Electrical: new circuits, panel upgrades, new outlets in new locations, hard-wired appliances, EV chargers, solar, generators.
- Plumbing: moving or adding fixtures, new water or drain lines, water heater replacement, gas piping.
- Mechanical: new or replacement furnaces, air conditioners, heat pumps, ductwork and vents.
Like-for-like repairs, such as replacing a faucet or a light fixture on an existing box, are commonly exempt. Some states only allow licensed contractors to pull trade permits, while others let homeowners do work on their own home. Ask your building department which rules apply.
Zoning approval is a separate question
A project can be exempt from a building permit and still need zoning approval, or still have to meet zoning rules. A 100 sq ft shed may need no building permit, yet it must still respect accessory structure setbacks and lot coverage limits. A 6-foot fence may need no building permit, yet a fence over 4 feet may be prohibited in your front yard. Many cities issue a simple “zoning permit” or “zoning compliance” for these smaller projects, usually with a site plan. Our guides on setback requirements and finding your property zoning explain those rules.
HOA approval is separate too
If your home is in a homeowners’ association, its covenants may require architectural approval for fences, sheds, decks, pools, exterior colours and additions. HOA approval doesn’t replace a permit, and a permit doesn’t replace HOA approval. Many owners submit to both at the same time using the same site plan and drawings.
What happens if you skip a required permit
Unpermitted work tends to surface at the worst time. Common consequences include stop-work orders and fines, double or higher permit fees when you apply after the fact, being asked to open walls or remove work for inspection, problems when selling because buyers, lenders and appraisers ask about permits, and insurance disputes after a loss. Our guide on building without a permit covers these risks and how to legalise existing work.
How long a building permit takes
Simple permits, such as a water heater or a small deck in a fast jurisdiction, can be issued over the counter or within days. Projects that need plan review, such as additions, garages, ADUs and pools, typically take weeks, and longer in busy cities or when corrections are needed. Our guide to the building permit timeline breaks down each stage.
What you usually need to apply
Requirements vary with the project, but a typical residential application includes:
- The application form with owner, address, parcel number and contractor details.
- A site plan showing the lot, existing buildings and the new work with setbacks.
- Floor plans for additions, ADUs, garages and remodels.
- Elevations showing height and exterior appearance.
- Structural details or engineer-stamped plans where required.
- Product documents, such as pool or shed manufacturer specifications.
- The fee, often based on project value or floor area.
How to get a firm answer for your address
- Identify the right office. City building department if you are inside city limits; county if unincorporated.
- Search the local code. Look for the “permits required” and “work exempt from permit” sections of the adopted residential code and local amendments.
- Check the department’s website. Many publish handouts such as “Do I need a permit?” lists for common projects.
- Ask directly. Call or email with a short description, size, height, and whether there is electrical or plumbing work. Note who answered and when.
- Check zoning and HOA rules even if no building permit is needed.
Signs your project probably needs a permit
- It adds floor area or a roof.
- It changes or removes structure: walls, beams, posts, rafters.
- It is attached to the house.
- It is more than about 30 inches above the ground.
- It involves new wiring, plumbing, gas or ductwork.
- It affects exits, stairs, guards or bedroom windows.
- It is in a flood zone or historic district.
Special areas that add permit requirements
Where your property sits can turn an exempt project into a permitted one. In a FEMA flood zone, almost any development, including fill, fences in some areas and accessory buildings, may need a floodplain permit; see our guide to building in a flood zone. Historic districts often require design approval for exterior changes such as windows, siding and fences. Coastal, wetland and steep-slope areas can add environmental review. And properties on septic systems may need health department sign-off before any structure is placed near the tank or drain field.
Common misconceptions about permits
- “It’s my property, so I can build what I want.” Building and zoning codes apply to private property.
- “A contractor said we don’t need one.” The building department decides, and the owner usually carries the risk.
- “It’s only a repair.” Repairs that replace structure, such as rotten joists, often need a permit.
- “Prefab buildings don’t need permits.” Size and use, not how it was built, decide.
- “Nobody will notice.” Inspectors, neighbours, aerial imagery and future buyers do.
Frequently asked questions
What size shed can I build without a permit?
The model code exempts one-storey detached sheds up to 200 sq ft, but many cities use 120 sq ft or less. Zoning setbacks still apply. See our guide to shed size without a permit.
Do I need a permit to replace a deck?
Usually yes, if the new deck is attached to the house, more than 30 inches above grade or larger than the exempt size. Replacing only deck boards is often exempt.
Can a homeowner pull their own building permit?
In many places, yes, for work on a home they own and live in. Some states and cities restrict trade permits to licensed contractors.
Do I need a permit for a fence?
The model code exempts fences up to 7 feet, but many cities require a fence or zoning permit regardless of height.
Do I need a permit to replace windows?
Often only if you change the opening size, affect egress or structural framing; some places require one for any replacement to check energy rules.
What if I already built without a permit?
Most departments let you apply after the fact, usually with higher fees and inspections that may require opening up the work.
