Accessory Dwelling Unit

This example in neighboring Corvallis shows an accessory dwelling unit on the left with the main house on the right. Philomath has been working on code language to make sure the city is in compliance with new state regulations on "mother-in-law cottages."

The Philomath Planning Commission came to a consensus during a June 4 work session that accessory dwelling units will be no larger than 600 square feet.

What makes that particular number so interesting is that it’s smaller than what surrounding government entities have considered — up to 900 square feet in Benton County and Corvallis, and up to 800 square feet in Linn County.

“We want it to stay ‘accessory.’ We don’t want two 900-square-foot homes side by side,” Philomath City Manager Chris Workman said about the planning commission’s decision. “We know there are several homes in Philomath that are 1,000 square feet or even a little smaller, a little bigger. That accessory dwelling structure should be a little smaller, 600 square feet.”

A new state law was established by the passage of Senate Bill 1051 during the Legislature’s 2017 session. A package aimed at easing a growing housing crisis around the state, the bill included a requirement for municipalities to allow one ADU for every single-family house.

For those not familiar with the term, ADUs are sometimes referred to as “granny flats” or “mother-in-law cottages.” They are generally smaller and cheaper to build than traditional single-family homes.

Benton County set a size limit of 900 square feet in an emergency ordinance passed last month for ADUs in unincorporated areas of the county that are located within urban growth boundaries. County commissioners have discussed the possibility of expanding the rules to include rural residential zones at a later date.

Philomath’s planning commission started to study the issue in a previous work session by taking a close look at how the county is handling ADUs.

“The city looked at what those county requirements are going to be and we’re just tweaking those on what we think is most appropriate,” Workman said.

The construction of ADUs in Philomath has not exactly been a frequent occurrence.

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“I think there’s an understanding that we’re not doing a lot of these; we’re not seeing a big demand for it,” Workman said. “So these aren’t going to have a huge impact and if that does happen, then I can always come back and we can always make changes.”

The 600-square-foot limit actually does not represent any change. The city’s current code also places the ADU limit at that size.

“Nobody over the last several years has asked for a larger accessory dwelling structure,” Workman said.

The planning commission also came to a compromise on an issue involving owner occupancy. Within a property zoned as Residential 1, owners would be required to occupy either the main dwelling or the ADU.

“I think requiring that the owner lives in one or the other, people understand that,” Workman said. “Most of the time when an accessory dwelling unit’s done, sometimes it’s an investment, but a lot of times, it is for the mother-in-law suite or somebody’s mom or parent needs to be looked after a little bit better and can have their own place still and have their independence and be close to home … to cut down on the expense of having to be in some type of nursing home or care home or something makes a lot of sense.

“Typically, I think the neighborhood understands that situation, so this would allow for that still but it would offset developers from coming in and making duplexes in single-family residential neighborhoods,” he added.

Planning commissioners on hand for the June 4 discussion were Steve Boggs, Gary Conner, Jeannine Gay, Lori Gibbs and David Stein. The group has scheduled another work session for June 18 at 6 p.m.

Workman plans to put an ordinance together on the most recent ADU discussion for possible planning commission approval.

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