Shed Size Without Permit: How Big Can a Shed Be?

Aspiring shed owners are frequently faced with the question of whether or not a permit is needed to erect their dream storage building. For many Americans, the answer to this question is based on whether or not the structure being built is over 200 square feet. While some jurisdictions consider 120 square feet the maximum, others use 150 as the magic number, and some will even require a permit for a shed of any size.

While many jurisdictions offer a size exemption for sheds or other accessory structures, building owners must still abide by local building, land use, and zoning regulations and obtain any required permits.

Below, I have detailed what I have learned about building a shed without a permit .

The 200 Square Foot Minimum

The 200-square-foot minimum is actually based on the International Residential Code, a model code adopted by many jurisdictions, including cities and states, which can modify, adopt, or reject the code in its entirety. According to IRC section R105.2, building authorities may exempt one-story detached accessory buildings with an area of less than 200 square feet from needing a building permit.

While this seems like a definitive answer, it is not necessarily applicable to your situation because while the International Residential Code (IRC) may provide a standard for detached accessory structures, local building departments can adopt their own rules and regulations concerning accessory structures and their permits.

For example, I have heard of cities that use 120 square feet, 150 square feet, and even 200 square feet as the minimum size requirement for a shed, but I have also heard of cities that do not allow any sheds without first obtaining a permit from the city.

What different shed sizes mean

For your reference, below I have provided some calculations using a few different sizes of sheds.

Shed size calculations shown above are based on the dimensions provided in this article.

An 8×10 shed equals 80 square feet and is likely small enough to not need a permit. This size of shed could be used to store a lawnmower, bicycles, and holiday decorations. A 10×12 shed equals 120 square feet and could fall under the magic number for some jurisdictions, while a 12×16 shed equals 192 square feet and would also be under 200 square feet. A 10×20 shed equals 200 square feet, which may be the magic number for some areas but may also fall under stricter local requirements.

Why the requirements are so varied

In the previous section, I spoke of different jurisdictions having different size requirements for sheds, but I did not go into detail as to why these differences exist. To speak more specifically to the issue at hand, different jurisdictions often have different interpretations about how building size should be calculated. Below, I have provided examples of different ways of calculating shed size as well as some rules of thumb that apply to the different methods.

Seattle adopts a 120-square-foot limit for sheds, but the city calculates a shed’s size according to the building’s roof footprint, which can include any overhang. Therefore, a 10×12 shed with a one-foot overhang on either end would be measured as a 12×14 shed, which has a footprint of 168 square feet. Meanwhile, Portland, Oregon, uses a 200-square-foot limit but measures the interior floor area of the building using the exterior walls as a baseline. In nearby Washington County, the limit is also 200 square feet but with a 15-foot height limit.

Milwaukee, Wisconsin, has a 150-square-foot limit, and New Castle County in Delaware has a 200-square-foot limit with a height restriction for eaves and overall height.

In Barrington, New Hampshire, the limit is 200 square feet, and setbacks are waived for sheds under this size, but if the proposed shed is located within a wetland buffer, it must be built on posts or pilings and must meet other requirements.

Local requirements can change, so these examples should not be treated as a universal shed permit rule.

As you can see, local requirements can greatly affect the square footage limit for sheds, and a building that would not need a permit in one town could need one in the next town over.

Setback rules are particularly important because they can operate separately from the building-permit exemption. Our zoning and setback guide explains why property-line requirements can affect a project even when its size appears to qualify for an exemption.

Other requirements even if you fall under the square footage limit

There are many requirements that are not about square footage that may be relevant to your project. The square footage limit is only an exemption from a building permit. Other requirements such as height, setbacks, and use restrictions are still in place, and if you fail to follow any of the requirements, you can be fined or forced to dismantle the building.

One important requirement is height. Many jurisdictions have a height limit for accessory buildings, including 15 or even 10 feet or less. Setbacks are another factor to consider. Your building may need to be a certain distance away from your property’s edge, and this requirement is usually applied as a zoning requirement and is separate from a building permit. While some jurisdictions reduce the setback for small accessory buildings such as sheds, others do not, and setbacks range from three to ten feet.

The use of the building can also be a factor. A simple storage shed is much different from a building that you intend to use as a residence, and any use of the building that requires electricity or plumbing will be subject to additional requirements. An electrical service to the building will usually require an electrical permit, and a sink or toilet will need a plumbing permit.

The building’s foundation can also be a deciding factor. Some jurisdictions allow buildings on skids or blocks to be exempt from permits, but the same building on a concrete slab may not.

If you are building in a flood zone, wetland, or steep slope, expect to have additional requirements beyond those that relate to building size.

What many people fail to realize is that the fact that their building will be exempt from a building permit does not mean that it is exempt from all requirements. Many jurisdictions have requirements that apply to all buildings regardless of whether or not they need a permit. Seattle states this on its website, stating that while some buildings do not require a permit, they still need to follow building, land use, stormwater, grading, and environmentally critical area requirements. If your building violates the requirements for setbacks or height, you can be ordered to remove or relocate the building, and a lack of a permit does not protect you from this order.

How to determine your maximum limit

Do not be fooled into thinking that a chart you found online or a permit your neighbor obtained applies to you. Instead, follow the steps below to determine your maximum size limit for a permit-exempt shed.

Determine your jurisdiction

If you are building within city limits, the city will be your jurisdiction, and if you are building outside of city limits, the county will be your jurisdiction. Some properties, however, can be in a special district with its own rules.

Research your jurisdiction’s requirements

Many jurisdictions have websites that explain requirements for accessory structures or that have a page titled something like “work exempt from permit” that details requirements. Some jurisdictions measure floor area by the interior, the footprint, or the exterior walls, so it is important that you pay attention to the fine print. The requirements your jurisdiction has for height and setback must also be taken into consideration. Many jurisdictions have additional requirements, including restrictions on use, requirements for foundations, and requirements for buildings in wetlands or flood plains. It is important that you make a list and cross out any requirements that your shed does not fall under.

Call the building department

I know that calling government offices can be a pain, but a five-minute phone call can save you months of hassle and thousands of dollars in fines. Ask the person you speak to if a shed of a certain size at a certain address will require a permit and what requirements you will need to follow.

For property-level research, you can also use the building permit search guide to understand how permit information can be researched by address.

Some additional tidbits of information

Failure to obtain a permit for a structure that requires one can result in you being fined or ordered to remove the structure. In some cases, you can be required to apply for a permit for the structure and have it inspected to ensure that it meets all requirements, and in extreme cases, you can be ordered to demolish the structure. It is not worth the risk to skip a permit for a shed when obtaining the permit can save you from these consequences.

Some people attempt to circumvent the requirements by installing their sheds on skids or wheels, and some jurisdictions do not consider these structures buildings, while others do. It is best not to assume that a skid-mounted or wheeled shed will not be subject to the same requirements. Sheds that are attached to a main building are considered to be part of that building and, therefore, subject to the requirements and permits that the main building is subject to. Even if a permit-exempt shed falls under the square footage requirement for your area, other requirements such as use or height can still apply.

The processing time for permits vary between jurisdictions, and some can take weeks or even months to process, so it is important that you apply for a permit far enough in advance.

Closing

As explained in this article, while the magic number for many jurisdictions for a permit-exempt shed is 200 square feet, there are some that have a lower magic number or no magic number at all. Even if the square footage of your shed falls under the magic number for your area, other requirements such as setback, height, and use still apply.

The best thing to do before purchasing or erecting a shed is to research the requirements for your area. Determine your jurisdiction, research the requirements on the jurisdiction’s website, determine your square footage and the way your jurisdiction measures that square footage, research the requirements for setbacks, height, and use, and call your local building department to confirm the requirements. This can save you a large amount of money and headache.

A shed is a great addition to any property, and with a little research, anyone can enjoy the benefits of a shed without running into any legal or financial issues.