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ADU Design-Builder Profile: Rainbow Valley Design & Construction Inc


Rainbow Valley Team

Rainbow Valley Team Photo

Quick Facts

  • Company Name: Rainbow Valley Design & Construction Inc
  • City: Portland, OR & Eugene, OR
  • Contact Name: Stephen Williams
  • Contact Phone: 503-888-8028
  • Contact Email:
  • Type of Company: Design-Build
  • # of Years Creating ADUs: 7
  • # of ADUs Completed: 5
  • Types of ADUs Created: stand-alone detached unit (new construction), basement conversion, addition

Check out Rainbow Valley ADU Profiles to see examples of their ADUs! For a more in-depth look, read Stephen Williams’ ADU: An ADU on the Alley

Stephen Williams of Rainbow Valley Design & Construction Inc has been designing houses since 1971. He first learned about ADUs at the Building Department of Portland’s Bureau of Development Services when he overheard another builder talking about them. He got curious so he picked up the ADU regulations and read them through. As he did, he realized that one of the places he’d lived years ago was similar to an ADU.

“Years ago, when I lived in Corvallis, we had a little cohousing community where we all had our own cottages. There were usually about 6-7 adults and however many children and dogs came with them.We shared a common house, and our cottage was like a little ADU without a kitchen or bathroom. They were small, probably about 200 SF. I raised my kids there.” –Stephen Williams

For Stephen, ADUs “just make sense.” He became interested in them as a building type and looked for an opportunity to create one.

“I’ve always liked smaller spaces, and ADUs make economic sense. When it comes to affordable housing, density, and cutting back, ADUs tend to be the most practical, unlike a McMansion. We did a remodel addition to a 6,000 square foot house in West Linn that just two people and two dogs lived in. I got tired of building spaces for people that are way bigger than anyone needs. Building ADUs and smaller spaces are definitely closer to my value system, than building a McMansion.” –Stephen Williams

As he designs an ADU, Stephen pays particular attention to a couple design considerations, namely natural lighting and creating usable outdoor spaces.

“Natural light is part of designing a building correctly, so I pay attention to where the sun is and the light is. Also, I think about the use of the space and sharing space. People assume both parties are happy to share an outdoor space. What really happens, if it’s a rental, is that no one uses it and both parties lose their ability to be outside. If you’re using it as a guest house or for your relatives the shared space works fine. With the Dunham Waugh ADU, they build the space for their son, so they’re sharing the outdoor space, which makes perfect sense. But if strangers are renting it, one or both people will be uncomfortable using it and then it’s empty wasted space. For my own ADU, I made a little courtyard that’s fenced away from the house, so it’s like two little houses. [See Stephen Williams’ ADU: An ADU on the Alley for photos and more info on his place!] For the Knoedler ADU I fenced off the yard for the house and then gave a balcony for the ADU.” -Stephen Williams

Stephen’s favorite design tricks for ADUs are open floor plans, lofts, dormers, and vaulted ceilings.

“Vaulted ceilings are crucial to get a sense of space in a small room. You can make a house feel twice as big by opening up the floor plan with a great room and adding a high ceiling. It’s never going to hold that much furniture but how much do we really need? Dormers just make sense. The bedrooms are very small by normal standards, but they don’t feel small. Sharing space physically and visually is what makes a small space work. You feel like you’re in a good-sized room.” –Stephen Williams

Stephen notes that one of the challenges of building ADUs is providing adequate storage. In the ADU Stephen built on his rental property, he put a little loft in in each bedroom. The tenant has a full drum set and that’s the only place in the whole house where he could store it, so that’s where it goes when not in use. The tenant’s daughter turned her loft into a sleeping nook for when she has friends over to spend the night.

“Storage is always a problem. With a tiny house like Dee Williams,’ people have to face the reality that they can’t have much stuff because there’s just no way to create a lot of storage, but in an ADU they feel like they should have decent storage. It seems like everyone should have an outside shed to put bicycles and lock them up out of the rain, too. Obviously, you have to get rid of a lot of stuff. We Americans have so much crap! The average size house in Japan is like an ADU here and they’re fine. The consumerism of this country is kind of frightening.” –Stephen Williams

The biggest building challenge for Stephen is system hook ups, particularly if the site for the ADU is lower than the sewer and a sewer pump needs to be installed. He notes that even though the infrastructure is already in place, the details of getting the utilities hooked up aren’t much different for an ADU than for any other house on an infill lot.

“They’re always a problem, you know. There’s lots of cost and hassle there that people don’t know about because it’s all buried and done.”-Stephen Williams

Speaking of invisible costs, Stephen says that sustainability is an interest for most of his clients, but it doesn’t usually survive as a driving factor of the design due to economic pressures.

“Most of the people that hire us want to use sustainable materials, so we work up the cost which is always way more than they want to spend. Then they cut all of that and we end up doing what’s required by code. On a building that small, it’s amazingly energy efficient. As far as certified material, some want to pay for it but most of them don’t. It really comes down to economics.” –Stephen Williams

Stephen says that one of the biggest challenges Rainbow Valley faces with ADUs is that most people underestimate the cost to build an ADU. They take the cost per square foot for a larger home and multiply that by a small square footage, assuming that’s what an ADU will cost.

“People assume a house that’s half as big will be half as expensive, but it still has windows, doors, a bath and a kitchen, so that’s really all the expensive stuff. People think ‘I could build that for 40K’ and there’s no way! We’re coming in at $250 per square foot. With the kitchen and bath, you can’t build for less than $100 per square foot, unless it’s a boring tract space with boring ceilings.” –Stephen Williams

Further compounding the frustrations, despite the sticker shock to the clients, the margins for builders to create ADUs remain slim.

“ADUs are a pain and we don’t make much money on them. It’s harder to make an operating profit on an ADU than an infill big house and it has just about as many headaches as a new house. The clients are still picking out the materials, even if they don’t need as much of each one. The profit margin is a quarter or an eight as much as it would be on a house that’s bigger.” –Stephen Williams

So why is Stephen still so committed to building ADUs?

“I’m still arguing ‘let’s do them!’ because they’re a good thing to be doing for the environment. Affordable housing is also a huge problem in this town and it has became a huger problem in the past 6 months. Rents have doubled!” –Stephen Williams

People are asking for ADUs and for Stephen the highlight of building an ADU is making his clients happy.

“This is a service industry. Obviously the goal is to either educate the client into a place where they’re ecstatic about what we ended up doing or we’re doing exactly what they wanted anyway. Happy clients equal referrals and more business. I do a lot of stuff in design that clients don’t necessarily understand and I think they discover the subtle qualities of the design after they’ve enjoyed the space for a while. I do hear that sometimes, too. They’ll tell me afterwards.” –Stephen Williams

So what advice does Stephen have for homeowners considering creating an ADU on their own property?

“Realize how much it costs and understand their value. Be realistic with your budget.” –Stephen Williams

About linamenard

Hi. My name is Lina Menard and I'm a small house dweller, designer, blogger, and builder. I'm currently collecting ADU Case Studies for Through my company Niche Consulting LLC, I help people design and build the home (and life) of their dreams! I also tell my stories about simple living in small spaces - like a travel trailer, a yurt, a backyard cottage, and tiny houses on wheels - at Niche News.

One comment on “ADU Design-Builder Profile: Rainbow Valley Design & Construction Inc

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