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Consider Adding an Accessory Dwelling Unit

Brought to you by John Robinson of Quality Residential Construction

A Quality Residential Construction Single Level ADU in Corvallis

If you are not already familiar with the term ADU, allow me to get you up to speed. Accessory Dwelling Unit (ADU) is an attached or detached residential structure that is an accessory to a single-family dwelling. Typical uses include caring for a family member, providing housing for your children during college or young adult years, or just providing rental income.

Adding an ADU to an existing property increases housing density and helps conserve land which is both expensive and in short supply. ADUs have been around for a while but are more commonly being built now due to implementation of Oregon Senate Bill 1051, signed into law in August of 2017. This law basically requires that cities allow one ADU to be constructed for each single-family home. The intent of the law was to improve the supply of housing and remove some of the common barriers of constructing an ADU, and to provide some standardization throughout the state.


“Increasing the housing supply through
ADUs or other middle housing types will
help provide much needed housing.”

In Corvallis in 2019 there were six permits issued for ADUs. In 2020, twenty-one permits were issued with nine of those ADU permits issued at the same time as a new single family dwelling permit. In 2021, six permits were issued for ADUs. In contrast, Albany issued zero permits in 2019, and one each in 2020 and 2021.

Another term you may not be familiar with is referred to as the “missing middle.” Middle housing includes ADUs, duplexes, triplexes and fourplexes. Middle is the term because they are between single family homes and large apartment buildings, and missing because they have been limited in where they can be built and thus often absent from current building stock.

House Bill 2001, which passed in July 2019, mandated that cities must allow construction of duplexes, triplexes, and fourplexes in single family zoned areas. The deadline for implementation for cities with a population over 25,000 was June 30, 2022. This bill also clarified several key issues with ADUs that cities were requiring such as owner occupancy and on-site parking. Both issues are now illegal for cities to require. The bill also required local government to consider ways to increase the affordability of middle housing by waiving or deferring system development charges (SDCs) and/or construction excise taxes (CETs). Some cities are still actively working on this issue.

SDCs in Corvallis for an ADU vary depending upon several factors but most fall within a range of $8,000 to $10,000. Corvallis also implemented an affordable housing CET that adds about $1,000 to the ADU permit. Currently, Albany does not charge a water SDC providing the existing meter is used, however all other SDC fees apply. Expect to pay around $8,000 in SDCs for an ADU in Albany. Albany does not currently have an affordable housing CET.

Eugene does not waive any SDC fees but will finance them for 10 years. In addition, Eugene has pre-approved and permit ready ADU plans on their website to encourage construction. Neighboring Springfield has waived all SDC fees except parks fees from July of 2017 to June of 2027. They estimate this saves between $5,000 and $6,000 on a typical ADU.

We have a shortage of housing state wide and this is a factor in driving up the cost of housing, whether renting or buying. Increasing the housing supply through ADUs or other middle housing types will help provide much needed housing. If you want to be a part of the solution, consider adding an ADU to your property.

At Quality Residential Construction, we can help you navigate the various permits and city regulations to build your ADU. Give us a call at 541-619-5787 and we will be happy to discuss your options.

This article appeared in the Real Estate Guide, September 2022.


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