The 200 Square Foot Shed Rule Holds in Fewer Than Half the Places We Checked

Ask the internet how big a shed you can build without a permit and you get 200 square feet. It is the figure in the International Residential Code, it is the figure in most of the buying guides, and it is a reasonable guess.

We have now read and dated the shed rule in 62 jurisdictions. Fifty-four of them state a threshold in square feet. Twenty-four use 200. The other thirty use something else, and the something else ranges from 36 square feet to 400.

That is an eleven-fold spread for the same question.

The distribution

A 10 by 12 shed is 120 square feet. It is permit-exempt in 50 of these 54 jurisdictions and needs a permit in four. A 12 by 16 shed is 192 square feet, just under the famous number, and now it needs a permit in 17 of the 54.

Virginia: twelve counties, one number

All twelve Virginia jurisdictions we cover use 256 square feet. Not approximately 256. Exactly 256, in every one.

That is because Virginia does not let them choose. The Virginia Uniform Statewide Building Code sets the exemption at 13VAC5-63-80, and local governments cannot adopt a stricter building permit threshold. Arlington and Culpeper County are very different places administratively, and on this question they are identical.

256 square feet is 16 by 16, and it is the most generous common threshold in our data.

Florida: nine counties, seven answers

Florida is the mirror image.

Broward and Lee County publish no numeric threshold at all.

Palm Beach County requires a permit for a shed over 36 square feet, which is smaller than a 6 by 6 garden shed. Miami-Dade allows 400. Those two counties are separated by a single county, and the permit-free shed you can build in one is more than eleven times the size of the one you can build in the other.

Florida operates under a statewide building code too, but its permit-exemption practice is set locally, and local is where wind-borne debris regions, flood zones and county administrative choices all land.

The one that is not an area at all

Mecklenburg County, North Carolina states its threshold as 12 feet, not as square feet. It is a linear dimension rather than an area, so it is not comparable to anything else in the table and we have excluded it from the counts above rather than convert it into a number it does not mean.

Seven more jurisdictions publish no numeric shed threshold, and they are excluded for the same reason: we would have to invent the figure.

What this means if you are buying a shed

Shed kits are sold in standard sizes, and the standard sizes sit right on top of the common thresholds. 8 by 12 is 96 square feet. 10 by 12 is 120. 12 by 16 is 192. 16 by 16 is 256.

Those are not coincidences on the manufacturing side, but they are coincidences relative to your jurisdiction. A 10 by 12 is under every threshold in our data except Palm Beach, Polk, Pinellas and Nashville. A 12 by 16 clears the 200 rule by eight square feet and fails the 150, 120, 100, 50 and 36 rules.

The number you need is the one your own jurisdiction publishes, and if you are within about 20 square feet of any threshold it is worth reading rather than assuming. That is the band where the received wisdom and the local rule disagree most often.