Storage Shed Requirements in Multnomah County, Oregon
In Multnomah County and other residential zoned areas in Oregon, a shed or "outbuilding" can be constructed without a building permit, so long as it meets specific criteria. Permits can be very expensive, so avoiding one is ideal. If the structure you want doesn't fit within the rules, however, you can pay for a building permit which gives you much broader possibilities.
The size of the shed is the first determining factor. The footprint of the structure must be 200 square feet or less, typically 10 feet by 20 feet. But as long as other restrictions are observed, any configuration resulting in no more than 200 square feet is acceptable. The other size restriction is height. The height measurement is a bit odd. Instead of absolute height of the structure, measure the roof vertically, from the top plates of the walls to the gable-end. Now, divide the figure in half. The measurement cannot exceed 10 feet without requiring a building permit.
Maximum Lot Coverage and Setbacks
All building codes need to be observed, even if you don't need to buy a permit. Placement of the shed is easy to overlook. There is a maximum percentage of your lot that can be covered by structures. If your house and existing garage take up all the allowable lot coverage, you cannot build a 200 square feet shed; it is limited to 150 sq. ft. to comply with the coverage rule, regardless of whether you buy a permit. For specific percentages, you have to check with Multnomah County or the the city of the building site within Multnomah County, as the percentages vary, depending on the density designation of your residential lot. Setbacks also need to be observed. A setback is the distance between a structure and the property boundaries. Setbacks are as follows: 20 feet to the street; a minimum of 5 feet to the side and back of the property line; and no less than 15 feet of setback from side to side. For example, you can build a structure that is 7.5 feet from the left and right property boundary or 5 ft from one and 10 from the other. Finally, there is a minimum space of 10 feet required in between buildings. It's best to measure the size and location of your existing structures on graph paper before you design and build an outbuilding.
While outbuildings can be convenient studios, playrooms, sleeping rooms, or shops all of them require utilities. If you want utilities of any kind, you will need to apply for permits. Once you apply for permits, understand that an inspector will be on your property to watch over how the work is conducted.
Get it Right
It's not uncommon for people to run electricity to outbuildings without a permit. Be very clear on this fact: if you break the rules, Multnomah County is fully within its authority to compel you to correct the problem, which in some cases may involved tearing down the shed.