Quick answer
In most US cities you can build a one-story detached shed up to 120 to 200 square feet, a freestanding deck under 30 inches tall and under 200 square feet, a backyard fence up to 6 feet, and a ground-level uncovered patio, all without a building permit. Attached garages always need one. These are national baselines, not promises: your city sets the real number, and even exempt projects must still follow zoning rules like setbacks.
Every backyard project starts with the same quiet question: how big can I make this before the city gets involved? The answer has real numbers in it, and this post gives you all of them, project by project. It also gives you the fine print, because the size threshold is only half the rule, and the other half is what actually catches people.
One note before the numbers. Almost every threshold below traces back to the International Residential Code, the model code adopted in some form across 49 states. The IRC sets the baseline, and then your state and city amend it, usually downward. That is why the same shed can be exempt in one town and require a permit in the next one over.
Every size limit in one table
| Project | Usually no permit if | A permit kicks in when | Over the line? |
|---|---|---|---|
| Shed | One story, detached, under 120 to 200 sq ft, no utilities | Above the local size cap, or any electrical or plumbing | Shed site plan |
| Deck | Freestanding, under 30 in. above grade, under 200 sq ft, not at the exit door | Attached to the house, elevated, or serving the back door | Deck site plan |
| Fence | Under 6 ft in back and side yards | Over the height limit, front yards in many cities, every pool barrier | Fence site plan |
| Patio | Ground-level, uncovered concrete or pavers | Any roof or enclosure, or electrical or gas lines | Patio site plan |
| Garage | Rarely: small detached garages in some cities | Always if attached, at any size; most detached too | Garage site plan |
Now the numbers behind each row, and where the common exceptions live.
How big a shed can you build without a permit?
For most of the country, the line is 200 square feet. The IRC exempts one-story detached accessory structures at or under that size from building permits, and roughly half of US jurisdictions use it as written.
The other half use something stricter, and the most common stricter number is 120 square feet. That is not random: before the 2009 edition, the IRC exemption was 120, and many cities still enforce the older figure. You will also run into 100 and 144 square feet. So a 10 by 12 shed (120 sq ft) is safe almost everywhere the exemption exists, while a 12 by 16 (192 sq ft) depends entirely on which number your city adopted.
Height counts too, which answers the other question people ask: exempt sheds are one story, usually capped between 10 and 15 feet depending on the city. California pairs its 120 square foot limit with a 12 foot height cap. New York City is the strictest major city: 120 square feet or less, no taller than 7 feet 6 inches, rear yard only, one per lot.
A few outliers worth knowing:
- Pennsylvania exempts detached structures under 1,000 square feet statewide on paper, the most generous threshold in the country, but virtually no municipality applies it.
- San Antonio allows up to 300 square feet, one of the biggest big-city numbers. Fort Worth, in the same state, requires a permit for every shed at any size.
- North Carolina measures dimensions, not area: any wall over 12 feet triggers a permit, so a 12 by 12 shed is fine and a smaller 8 by 16 is not.
- Florida has no blanket exemption at all, because every shed must meet hurricane wind-load rules.
Two more things. Putting the shed on skids instead of a slab does not change the math in most cities; the size cap decides, not the foundation. And running any electrical to it, even one outlet and a light, requires an electrical permit even when the shed itself is exempt. The full state-by-state breakdown is in our shed permit guide.
What size deck can you build without a permit?
The number everyone remembers is 200 square feet. The number that actually matters is 30 inches.
To skip a deck permit in most jurisdictions, your deck has to pass four tests at the same time:
- 200 square feet or smaller
- No more than 30 inches above grade at any point
- Freestanding, not attached to the house
- Not serving the required exit door
Fail any one and you need a permit. That makes the exemption far narrower than it sounds: a 100 square foot deck attached to the house needs a permit. A 150 square foot freestanding deck three feet off the ground needs a permit. A low platform off your kitchen door needs a permit, because it serves the exit. The truly exempt deck is a small, low, freestanding platform sitting out in the yard, which is not the deck most people are planning.
Local variations tighten it further: Seattle draws the height line at 18 inches, Virginia caps exempt decks at 12 by 12 feet, and Miami-Dade County exempts only wood decks 18 inches or lower. The deck permit guide covers the rules state by state.
How tall can a fence be without a permit?
Fences trade square footage for height. The dominant pattern nationwide: no permit for fences up to 6 feet in back and side yards, with front yards limited to 3 or 4 feet by zoning almost everywhere.
The model code is actually more generous, exempting fences under 7 feet, but most cities lower it to 6. The spread is wide: Phoenix requires a permit for any fence over just 3 feet, while Houston exempts non-masonry fences all the way to 8 feet. Material matters too. Masonry and concrete walls get lower thresholds, like Portland, where a wood fence is exempt to 7 feet but a masonry one needs a permit above 4.
Two absolutes: a fence that doubles as a swimming pool barrier always needs a permit, with no height exemption anywhere, and corner lots face sight-triangle rules that cap anything near the intersection at around 3 feet regardless of permits. Details and state specifics are in the fence permit guide.
Can you build a patio without a permit?
Usually, yes. Patios are the friendliest category, because a ground-level, uncovered slab or paver surface is treated as hardscaping, like a driveway, rather than a structure. The working frame mirrors the deck rule: at or near grade, under 200 square feet, detached, and not serving the exit door, and most departments will not ask for a building permit at all.
One word changes everything: cover. Put a roof over that patio and it becomes a structure nearly everywhere. Houston and Los Angeles County require permits for all patio covers at any size. Phoenix exempts freestanding covers under 200 square feet, San Diego under 300. Enclosing the space, or adding electrical or a gas line for an outdoor kitchen or hot tub, triggers permits the same way. If your plans include any of those, start from the patio permit guide rather than the exemption.
Can you build a garage without a permit?
Plan on no. An attached garage requires a permit everywhere, at any size, because it shares walls, a roof line, and fire risk with your living space.
Detached garages are the only opening, and it is a narrow one. Some cities extend the 120 to 200 square foot accessory-structure exemption to them, but many building departments read the code's exemption list, which names sheds and playhouses, as not covering garages at all, since they store vehicles and fuel and sit on engineered slabs. Seattle requires a permit for every garage. Even Pennsylvania's famous 1,000 square foot exemption applies only to detached structures, never attached ones. Treat the garage permit guide as the starting point, not the exemption.
"No permit required" never means "no rules apply"
Here is the fine print that catches more homeowners than any size threshold. An exemption waives the permit process: the application, the fee, the inspections. It does not waive the building code, and it does not touch zoning.
That means every exempt structure still has to respect:
- Setbacks, the required distance from each property line, often 5 feet or more for accessory structures
- Easements, utility and drainage corridors where nothing can sit, even a "no permit needed" shed
- Lot coverage caps, which limit how much of your parcel structures can occupy
- Height limits and placement rules, like rear-yard-only requirements
- HOA rules, which apply on top of everything the city says
Cities enforce these on exempt structures all the time, usually after a neighbor complaint or an assessor's aerial photo. A shed built 2 feet from the line where zoning requires 5 has to move, permit or not. So the size question is really a placement question in disguise, and the way to answer it is the same drawing the city would ask for anyway: your lot to scale, with the structure and its distances marked. That is what a site plan is, and sketching one before you build, even for an exempt project, is what keeps the exemption from turning into a violation.
Over the line? The permit is paperwork, not a crisis
If your project crosses the threshold, what the city actually wants is manageable: an application, a fee, and drawings, and the first drawing on nearly every checklist is the site plan showing your lot, the structure, and its setbacks.
That part we can take off your plate: permit-ready site plans drawn from county GIS records and satellite imagery start at $89 with 24 to 48 hour delivery and free revisions until your building department accepts, and 98% are accepted on first submission. The permit fee itself is usually modest for these projects; check typical fees by state and project or get a number for your city with the permit cost estimator.
If your city accepts hand-drawn plans and your structure sits comfortably far from every line, you can also draw the plan yourself in an afternoon: the six-step walkthrough shows the method honestly, and the Pre-Submission Checklist is the quality gate before it goes to the counter. The trade to know upfront: the afternoon is free, but a correction notice for a drawing that is off-scale or missing setbacks costs you a redraw and another trip through the review queue.
How to find your exact number in five minutes
- Start with your project and state. The guides for sheds, decks, fences, patios, and garages list the thresholds and the state-specific exceptions.
- Check your city's own exemption list. Search your city's name plus "residential permit exemptions." Most building departments publish the list on one page.
- Ask the counter two questions, not one: "Does my project need a permit at this size?" and "What are my setbacks?" The second question applies even when the answer to the first is no.
Already built past the line?
It happens, and the fix is more routine than most people fear. If you are weighing the risk, our guide to building without a permit covers what skipping one actually costs, and what happens if you build without a permit walks through discovery, fines, and stop-work orders. If the work is already standing, the standard path is a retroactive permit, and the application will need the same site plan a new project would.