Working with BDS
Portland’s BDS (Bureau of Development Services) has a fantastic website full of helpful information. Here are a few online resources:
One of the challenges to building an ADU is that there may be zoning limitations that prohibit the size, shape or placement of your building. It’s important to realize that there are many criteria regarding ADUs that must be considered carefully before beginning. Some key points include:
- Building size: Limited to 33% of original house size or 800 sq ft – whichever is SMALLER
- Overall building bulk. The ADU and accompanying outbuildings cannot cover more than 15% of the total property coverage
- Height: Limited to 18′ (measured at the midpoint of roof slope)
- Design: the ADU must fit the aesthetic of the exiting house. Roof slope must match, similar materials, etc.
Because my project entails building an ADU on top of an accessory unit, I need to apply for TWO adjustments:
- Adjustment to the Sq Footage limitation. I will be applying to build an 800 Sq Ft. ADU. Since my house is not even 1000 Sq Ft, I need the adjustment to build bigger. The zoning code affecting this is Zoning Reg 33.205
Adjustment to the overall size/scale. Because the ADU will be built atop a shop/garage, the building will be larger than the original house. Zoning code 33.110.250 addresses this issue (Summary of Purpose Statements – Single Dwelling Zones) I will need a SECOND adjustment for this change.(Update – this may not be true. Looking at the exact zoning language, it states that the COVERAGE cannot be larger than the main house. Need to check to see if this is indeed the case. Here’s a complete copy of the zoning code in question: 33.110 zoning regs)