Township building codes.

[Jim Becker]

A way to get around the 10 foot rule that is to be sure the auxiliary structure is less than 100 square feet. Garden sheds and small, portable, auxiliary structures <100 SF do not require permits in our town. One gentleman in our neighborhood has a shop created out of several 8 X 12 garden sheds all lined up right on the property line and very close to the house.

Permits and zoning are two separate things. While a residential accessory building under 200 sq ft might not require a permit, it will still be subject to zoning setbacks in most jurisdictions unless it's specifically called out in the details of the particular residential zone regulations that apply to the property.

[Bill Dufour]

Most of california sheds under 120 square feet can be on the property line, no permits, etc. Some height rules and no overhang over a fence line. Add power or water and you need permits. Two such sheds allowed per one lot.
The 120 sq feet is the max size sold at box stores.
BilLD