Data from Homeowners in Portland Who are Planning to Build ADUs

The first ADU class was fantastic and I want to thank the class for making it such a fun experience for me.

Next, I want to share some information derived from the class questionnaires. The questions were in large part to help me figure out what to teach, but I included some other questions that would help provide some insights into the minds of homeowners who are likely to build ADUs.

When asked "What is your motivation to build?", here are the responses. Respondents could check up to three choices.

The most common response for the "biggest barrier to building an ADU" from the respondents was cost/financing (which is not really a surprise). Incidentally, I'm proud to say that every respondent said that the class helped them figure out useful approaches to address their biggest personal barrier, which ranged from permits, cost, financing, lack of knowledge, "taking the leap", city rules, neighbors, to finding the right designer and builder. 

Every respondent said that they would use a general contractor instead of trying to general contract it themselves. This uniform response was probably due in part to the information that they learned in the class, but I was still surprised to see a consensus since I did not specifically advise people not to general contract it themselves. 

50% are planning detached new construction. 25% are planning conversion of an existing garage, and 25% are planning on attached new construction.

Over half of class participants were in the 40-50 age bracket.  The other ages ranged evenly in a bell curve from 20-70. 

Here's a picture of the class during the walk-through tour of the ADU.

Walk-through Tour of the ADU

And, here's the last slideshow from the class, which shows the ADU construction process, step by step. 

ADU Construction Process (in pictures)

View more presentations from Kol Peterson

For those who were unable to make the first class, I'm offering the ADU class again on Sunday, November 6th.

Final ADU Project Costs and Living Free

Cost is a big issue for homeowners who want to build ADUs and I am committed to being transparent about the costs of my project. So, now that the project is "done", this post deals with the total project cost. In the end, my total costs ended up being $96,238, which is $120/sq. ft.

The total cost for designing, permitting, and building the ADU was $96,293.

I had initially aimed to complete the project at $100/sq ft, but I suppose that my cost overrun was somewhat expected. As I wrote in my first 'time and cost' blog post, it is a rule-of-thumb that a project will end up costing 20% more than what was expected, and that it will take twice as long as expected.  Well, the project came in on time, and it came out qualitatively great, but it cost 20% more than I had anticipated, confirming the Project Management Triangle adage. 

You can build a high quality project at low cost, if you have lots of time. 

You can build a high quality project in little time if you have lots of money. 

You can build quickly and cheaply if you do not expect great quality.

On the bright side, due to the excellent thermal performance of the building (it is projected to use 1/3rd the amount of the energy of an average Oregon home), the Energy Trust of Oregon gives me $1,750 rebate-- no chump change. I anticipate that I'll get another $1,000 back in energy incentives for the appliances that I purchased from the Oregon Department of Energy via tax credits.

I will go into greater depth on this cost and rebates in my upcoming ADU class. My other posts about financing, the permit costs, and the financial payback may be helpful to others as well. 

Using the approach that I am using (moving into the ADU and renting out the the main house) means that I will likely live the rest of my life without any rental/mortgage expenses. What an amazing feeling of freedom to have at my age.

Assuming that it would cost me $1,000/month to rent an equivalent space, the payback period on the ADU is 8 years. My main house rents out at a rate higher than the mortgage payment, so in addition to paying for its own mortgage, it's providing some additional income.

Of course, this ADU model is not going to work for everyone who builds an ADU, but it is certainly a compelling option for some people with access to the upfront capital, who are excited about living in a smaller space and renting out their main house. 

I do not mean to pitch ADUs solely as a vehicle for financial freedom, but my story proves that this financial model to live at no cost is totally attainable with an ADU. There are many reasons to build ADUs: boosting the local building sector, providing green jobs, providing urban infill housing, reducing municipal infrastructural demands, building community, creating more comfortable multi-generational housing options for families, affordable housing, building smaller spaces for energy efficiency, and reducing climate impacts. 

Personally, what I like about ADU's best is that they are a significant way that an individual can make a difference in terms of growing and developing smarter urban spaces. Typically, smart growth is "done" by developers, financiers, and municipalities- big actors in the land development world. With ADUs, smart growth can be promoted at the block level by an individual. An ADU can be a grass roots, contextualized, organic, hyperlocal form of development, providing a better residential development alternative to sprawl.

But, if none of the ethical or academic justifications are compelling enough, it doesn't hurt that ADU's are almost definitely going to be a source additional income or residential flexibility for anyone who is able to build one.

When It Rains, It Pours: Five Big Announcements

Today was a big day. Here are five announcements that I am very happy to share:

1) We passed the final inspections, which means that the ADU is now officially verified and ready for occupancy! Building the ADU has been a huge undertaking for me and I am relieved to finally have it officially completed. And a big thanks to Stephen Smith, who has served as the builder for this project.

 

Generally speaking, I've found Portland''s Bureau of Development Services, the building permitting authority, to be fair and reasonable, despite being short-staffed. It took a couple attempts for us to resolve relatively minor building issues (eg. guardrail height, smoke detector type) before we were able to passing the final inspection.

Meanwhile, there's still some more finish work to do in the ADU and throughout the site, and I'll continue to post updates on those projects (look for upcoming posts on the water heater, stairs, and the final budget numbers).

2) The ADU has been selected to be on Portland's Build It Green Tour, a self-guided tour of twenty-two of the premier 'green' new construction and renovation projects around the City of Portland, on Saturday, September 24th.

The ADU will be one of several smaller homes on the tour. I visited 15 homes on the Build It Green tour last year, and found some of the projects, particularly the Passivehauses, to be inspiring from an energy use perspective. There are interesting homes on the tour this year; if you're in the Portland area, I encourage you to check it out.

Portland's Build It Green Tour: Saturday, September 24th, 2011, 11 a.m. to 5 p.m.

3) The ADU has been selected to be featured on KATU, a local TV news station, to help promote the Build It Green tour. They'll be filming here next week and the piece will be aired the week prior to the Build It Green Tour. I hope that they post their pieces online so I can link to it. It's an honor to have the ADU selected for this news piece from amongst all the great projects on the tour, and it has given me added motivation to get the ADU looking good.

4) Earth Advantage Institute is offering a free hour class on "Creating Not So Big Homes", which will be hosted at my ADU on the morning of the Build It Green Tour. Here's a link for registration information.

5) On Saturday, October 15th, I'll be offering a day-long class for homeowners in the Portland Metro area, entitled 'Building an Accessory Dwelling Unit on Your Property in Portland'

With my personal ADU project nearing completion, I am ready to help others who hope to build an ADU in Portland. This class is intended for homeowners interested in building an ADU on their property. Readers of this blog know that the process of building an ADU can be complex, overwhelming and expensive.

The goal for this class is to help homeowners create a more beautiful and functional ADU space that will augment their property, maximize small space, and lower short and long term design, build, and maintenance costs for the ADU. It will cover the essential ADU design/build elements from start to finish, which will result in a more beautiful space and will hopefully help them save significant time and money.

Here's a link to more information about the class and the registration. http://pdxadu.eventbrite.com/ 

Saturday, October 15th, 9am-5pm. 

$95 (or 8 hours work/trade)

I plan to hold the class at my ADU 

ADU Building System Science and Building Program Design Overview

This long and somewhat technical post is intended for those who are interested in building an ADU themselves, or who are interested in building science. There's a 13-minute audio/visual presentation at the end of this post that covers some of the same information in presentation format. 

Building Overview

• The goal for this project is to design and build personal housing that is financially sustainable. 
• Projected cost for the design, permit, and construction is $92K, which equals $115/sq ft. 
• 799 sq ft and its location is very walkable and bikeable.
• Northwest Energy Star certified through Earth Advantage Institute with a EPS score of <40.
• Notable design features: staggered stud wall construction, slab-on-grade,  92% efficient tankless water heater for radiant floor and potable water system, heat recovery ventilator, passive solar orientation; space efficient design accented by acid-stained concrete floors, exposed beams, and accent lighting.

Residential Sustainably – Living Small at No Cost

My concept of sustainability includes a financial component. I have explored a variety of low-cost, creative living ideas, and eventually decided on the idea of building an Accessory Dwelling Unit on a single family lot with a pre-existing primary residence. In this model, my financial goal was that the pre-existing house on the lot would pay for itself through rental income. Upon completion, I could live in ADU without paying the monthly mortgage on the main house. With this idea in mind, I purchased a single family home in 2010 with the intention of building an ADU on the property.

Conservatively assuming that the ADU would generate a $1K/month in rental income (if I were not living in it), a $100K investment roughly translates to an 8.3 year investment payback period, with an annual return of 12K after that payback period. Here are some variables that could alter this payback period:

    *         the construction could cost more or less than anticipated (+/- 15%)

    *         the rental income may be more or less than the mortgage payment (+/- 20%)

    *         there could be unforeseen maintenance costs on the primary house

I will not make much profit from the monthly rental income from the primary residence. However, I am confident that the investment will allow me to live at little to no cost for housing after this investment. Additionally, I am confident that the investment will eventually pay for itself and generate surplus income. This accomplishes the initial financial benchmark that I was seeking to achieve for this project.

Accessing tens or hundreds of thousands of dollars is the biggest barrier for those who are seeking to design and build an ADU. If one can surmount that significant financial hurdle, ADU's have a lot of potential payback.

Selecting a House with an Appropriate ADU Site

 

A critical factor in purchasing a house was the viability for the lot to gracefully host an ADU. The neighborhood was obviously important for many reasons, but so was the micro-neighborhood, and of course, the property and house itself was an important factor. When I found the property in NE Portland, it seemed well suited to the ADU design goals in these three categories.

Neighborhood Livability: The address scores a 71 on WalkScore.com, but that doesn’t reflect how very walkable and transit oriented the neighborhood feels; house addresses 5 blocks away in either direction score 8 points higher. From an energy perspective, this urban location allows residents to easily reduce travel related emissions significantly for work downtown, as well as from running regular errands.

Micro-Neighborhood: The micro-neighborhood has a range of architectural styles—the next door neighbor lives in a yurt, and another home is sided with corrugated aluminum. Due to the wide range of architectural styles adjacent to this yard, the ADU is well-suited to this pocket of Portland. The homes in the immediate vicinity are oriented towards the street front side of their lots- in our 50’ x 100’ and 50’ x 50‘ lots, the yards are grouped together.

Property:  My primary house facade is only 11ft from the front sidewalk, leaving me with ample depth in the rear yard for a new 27’ length structure. I visited approximately 60 properties in NE Portland before finding this one. Overall, this house and the land purchase was competitive in terms of its current value, and even more valuable in light of its potential future use as a home with great ADU.

Site Selection: The ADU will sit on the north side of the lot. There is a gorgeous 60’ Cherry tree canopy on the south side of the lot, shading the ADU throughout the summer, and allowing light to pass through during the winter months. The extensive canopy provides a wonderful viewshed from the south-facing windows, so the majority of the glazing is oriented South. The ADU will have short eaves to match the trim on the primary house in accordance with Portland’s ADU regulations. In mid-summer, when the sun is above the canopy at noon, the short eaves will cast just enough shadow to block direct exposure through the clerestory windows. Most of the windows will receive dappled sunlight; the canopy will block direct sunlight 80% of the day.

The Building Envelope

The building envelope design goal is to achieve a high performance shell at a low cost. Rather than attempting to achieve Net-zero or LEED or Earth Advantage certifications, which require allocating funds towards particular materials, products, or renewable energy such as solar panels, I am investing proportionally more money into air sealing and insulating the building shell than in other facets of the building design. We’re using best practices for air sealing, adding redundant air barrier systems that are somewhat vapor permeable. Blown-in fiberglass is the insulation type for the 8 ¾” wall and 10 ¾” ceiling cavity.

Wall Assembly (from exterior to interior)

•     Cedar siding shingles- a naturally water repellant composition.
•     Rain screen from strips of dimple board, through which the shingles will be nailed.
•     Weather Protective Barrier- Siga Majvest weather protective wrap and Siga Wigluv tape for the plywood sheathing joints. The Siga wrap and tape are also vapor permeable.
•     5/8” Plywood sheathing to which the shingles will be nailed.
•    Staggered studs framing. Selected because it provides a 8 ¾” insulation cavity and has less thermal bridging.
•     Loose fill blown in fiberglass- R33
•     Drywall
•     Paint

Roof, Slab, and Glazing: The roof assembly will be R44 and the slab on grade floor will be R-15. The slab is thermally broken from the foundation walls (using 1” EPS foam) and the gravel (using 3” XPS foam). The windows and French door will be vinyl, with a U-value of 0.30 to comply with Energy Star standards.

Heat Loss Calculation: Earth Advantage conducted an energy use calculation using a RemRate analysis and found that the ADU will use 39.6 Million BTU/year. Based on an assumed performance of 6.5 air changes per hour @ 50 pascals, the Energy Performance Score (EPS) will be 40 (EPS is a simple numeric score that correlates with the Million BTU/year for a given home. The average new Oregon home has an EPS score is 89, so the ADU will use less than half that amount of energy. The ADU will likely beat that 6.5 ACH air sealing benchmark, which will in turn lower the EPS score by several points.

For the heat loss calculation, I assumed that 83% of the wall assembly will be R-33, 17% will be R-6 due to thermal bridging at the corners, door and window jams. The ADU will have 0.15 air ACH under ambient conditions. Because the ADU does not have ducts and will have a heat recovery ventilator (HRV) to balance pressure and moisture, there will be very little air pressure differential to drive air loss through leaks. The HRV will provide 60 cubic feet per minute of fresh air and capture 65% of the heat energy from the air vented.

Since the ADU is going to have tankless water system to heat potable water due to space constraints, we have overlaid that function with providing hot water for the radiant floor system using a heat exchange. We will be using the Navien condensing tankless combination water heater, which is 92% efficient natural gas water heater.

The heater will be situated inside the thermal envelope to eliminate any heat loss leak potential. There will be three radiant zones: one in the concrete slab on the first floor, one in the bedroom in a vacated air space under wood flooring, and one zone in the upstairs bathroom. 

Materials

 

I had notions of using mostly salvaged construction materials as a mechanism to reduce upstream waste and reduce costs, however this proved to be impractical. While it may have saved some money, it would have taken too much time to find used lumber and other building products. And, I’ve learned that many constructional materials must be new, such as the foam, concrete, nails etc. As a rough guess, pound for pound, this project will be 95% new materials, 5% used. This ratio is disappointing to me, as I would have loved to reuse materials to a greater extent. However, many of the finish materials and fixtures will be salvaged: flooring, railings, sink, tub, doors, and possibly other finish materials such as paints. 

The building mechanics are designed to be relatively simple. The mechanical systems are limited to the water heater, heat recovery ventilator, and the appliances. The new appliances will all be Energy Star certified and several of them will be eligible for substantial rebates from the Oregon Department of Energy. 

Indoor Air Quality

There will not be much ductwork in this ADU except for a couple short duct runs associated with the HRV. The HRV will vent the bathroom, and the gas stove will be direct vented. The HRV will bring in a constant supply of fresh air based on a weekly cycle. Additionally, the open, lofted floor plan will allow me to leverage the stack effect and winds to air condition the ADU through operable windows on East and West sides of the structure. All of the floor and wall surfaces in the house will be hard; there will no carpets to collect dust. We’re using a high-quality weather resistant barrier in additional to cedar shingles, so I don’t anticipate any moldy conditions in the walls.

Quality Control

The ADU will get Energy Star certification through Earth Advantage to help ensure that the builder is using the best available framing, sealing, and insulation practices. The builder must build to Energy Star standards and is contractually obligated to use the ‘Thermal Bypass Checklist’ and relevant ‘Critical Details’ and ‘Tech Tips’ from the Northwest Energy Star website. To help ensure good water protection and air sealing quality, we are using SIGA Majvest weather resistive barrier and Wigluv sheathing tape. We are getting technical drop-in visits from the Energy Trust subcontractor outreach specialist. Earth Advantage will be conducting a blower-door test to check the air pressure and to help identify any sealing gaps.

Summary

This ADU project is an attempt to design and build a small, beautiful structure, and develop a zero-cost residential financial model. So far, it has been very successful. The ADU is under construction now and it is looking wonderful. The costs have increased from my initial goal of $100/sq ft to $115/sq ft, but this is still a relatively low cost for the product and building performance that I am expecting to achieve.

My parallel goal for this project is to document and write about the design build process with a strong focus on ADUs, and the nuances associated with their development. This project has sparked a new passion for me, blending my interests of green building, environmental and urban planning, and policy. I hope to use my personal building experience, and green building background, and governmental experience to help other individuals and communities who are seeking to build ADUs, and to help others design better, tighter, and greener.

Here's a slide presentation that covers some of this same information.

Building an Accessory Dwelling Unit In Portland from Kol Peterson

The Permit and the ADU Design Build, Time and Cost Breakdown

Six and a half weeks after submitting the permit application to the City of Portland, we have gotten the permit! Needless to say, I am thrilled to move forward with the construction phase. 

We're going to be moving really fast now, so I'll be posting frequent updates of the construction process. In the next two days, I'll post pictures and videos of the groundbreaking, excavation, and foundation wall forms.

This post however, is about the costs and time of this initial phase of the project, as well as the cost of the ADU project overall. I know that cost is the most major factor for everyone who is considering such a project. So, I'll be transparently reporting on the costs of this project so that others have a good sense of the costs involved.

To start, it is very noteworthy that Portland has temporarily waived all System Development Charges for ADUs. System Development Charges, which are the city's administrative fees for transportation, water, and waste management for all new construction projects, typically ran $10,000 for ADUs. This policy has obviously been a major recent incentive for many residents to consider building new ADUs (or legalize their existing ADUs).

Portland took this measure to actively promote ADUs to add density to the urban core. This is one the many laudable urban planning policies that consistently keeps Portland near the top of the list for being on the nation's most livable, walkable, and bike-able cities.

System Development Charges for ADUs through June, 2013.

ADU Costs

One of the goals for this project is to build high-quality custom construction at a relatively low cost; partially by making better design decisions, and partially by sourcing materials and labor astutely.

Here is a time and cost breakdown of the design phase that I just completed, which amounted to $8,196.

Design Phase Cost Time Breakdown

Generally speaking, custom high quality construction costs $150-200 sq. ft. My original goal was to get the whole project done for $100 sq ft, but it's looks like I won't be able to get the project costs that low.

Here are my current cost projections. If I am able to stick to this budget of $88,196, the project will cost ~$110 sq ft.

Of course, there's a well-known rule of thumb that says that you should always expect to pay 20% more than what you estimated, and that the project will take twice as long as you had hoped.

Building To Code

Many people are interested in building ADU's and the daunting capital expense is their only deterrent. I know that some have converted garages into livable spaces for as little as $20K without a permit, and that others spend up to $200K to build an ADU from scratch with a permit. Since this post comes in conjunction with the permit, I've attached the line item Portland BDS permit fees below for reference, which, for this project, amounted to $4,205.38.

Building legally requires more work that building illegally and it comes at a cost. However, it gives more peace of mind, legal assurance, and better financial payback to the homeowner for rental and resale. Building legally or not is a big decision that the homeowner must carefully consider.

If you're considering whether and how to build a new structure in accordance with the city's rules , I've found that the City of Portland BDS is great about answering questions about new construction by phone or in person. So, don't hesitate to sit down with them and talk frankly about your ideas--you don't even have to give them your address if you're still trying to decide how to proceed.

The City Of Portland permit costs amounted to $4,205.38 for this project.

I'm curious to understand how this permit fee compares other permit fees around the country, and whether the fees are structured on a per sq ft basis.

To me, this permit fee seems reasonable. If the $10K system development charges were in effect, I would have balked at funding this project. So, again, I applaud Portland's active promotion of ADUs.

Quality, Cost, and Time

There's a huge range of tactics that effect project cost. But, my Sustainable Home Professional instructor introduced me to a great rule of thumb, called the Project Management Triangle:

'There are three relational pillars in every design/build project: Quality, Cost, and Time- and it's hard to optimize all three pillars.'

In other words, you can build a high quality project at low cost, if you have lots of time. You can build a high quality project in little time if you have lots of money. And you can build quickly and cheaply if you don't care about quality.

Finding that sweet spot in the middle is really tough. But, that doesn't mean we can't try!

A Passively Virtuous Choice

It is a government's grander policy challenge to steer individuals towards the personal choices that result in the best societal outcome; to purposely induce the virtuous choice by making it a passive choice.

I'll define a 'passive choice' as the expected behavioral choice that a self-interested or apathetic person would reasonably make.

Optimally, individuals' passive choices will collectively result in the best societal outcome. It is in our best interest to design systems where individuals' passive choices are the most regenerative for society. Collectively, we should design for the adoption of individual behaviors that benefit everyone, whether or not the individual is actively choosing to be virtuous.

For example, if driving to work is cheaper and quicker than taking the bus or biking, then more people will surely choose to drive. 

Conversely, if driving to work takes more time and costs more money than taking the bus or biking, then more people will choose these alternatives. 

Generally speaking, marketing the adoption of energy efficiency choices is easier than marketing behavioral change. For example, most environmentalists understand that driving alone has a bigger environmental footprint than taking the bus. But, if you’re accustomed to the ease and costs of driving alone to work, it is difficult to force yourself to change your behavior to take a bus every day. Therefore, a policy that asks citizens to drive alone less, is not as pragmatic as a policy that encourages us to purchase a more efficient vehicle.

If we want people to get out of the habit of driving their car alone for their daily commute, then driving alone cannot be the passive choice. Biking or taking transit must actually become the best way for people to get to work in terms of cost and time savings. If we are to bike or bus to work, society must strive to make it the more compelling option, the passive choice. 

Many environmentalists advocate for behavior change and there is a place for that. But, out of pessimism, mixed with a cup of pragmatism, I prefer to advocate for design change. 

ADU’s have the potential to help us passively make virtuous societal choices in the face of many looming environmental threats, not the least of which is climate change. The building and transportation sectors are the two most energy intensive sectors in the US.

 from Architecture2030.org
The charts above show the energy and carbon dioxide emissions 
associated with various sectors of the US economy. 

Smaller, urban infill housing represents an energy cure in the building and transportation sector. Compact, infill housing is akin to surgery intended to fix the clogged arteries of the building and transportation sector.

Urban density is a prerequisite for a robust and healthy transit system. ADU’s have potential to organically add density to the urban core in a meaningful, personalized, creative way.

From 'Research on Factors Relating to Density and Climate Change'.

The chart above shows the minimum number of 

residential dwelling units per acre needed 
to economically justify the associated transit service.

ADU’s are, by definition, smaller than the average residential dwelling; and building smaller is arguably the single most significant factor in building greener. 

ADU’s have the potential for a rapid payback period. In my case, I am striving for a five year payback period, a period which qualifies as a good business investment.

Economically, ADU’s are a shot in the arm for a homeowner's personal financial portfolio, the city's tax base and the state's unemployment rate. They also could help satiate the nation's thirst for creating US-based "green" jobs in a down economy.

Whether or not I cared about the green house gas reduction benefits or the benefits to the local economy, my self-interested choice to build an ADU is a societally virtuous one.

Common Forms of Living Smaller

Much residential "green building" attention has been placed on material selection, alternative power sources, and mechanical efficiencies. These choices all play a role in building "green", but arguably, none of these charismatic green features are as important as the energy efficiency gains achieved through building and living in smaller spaces. 

Smaller houses can take many forms, and the three common forms that I'll mention in this post, all achieve notable reductions in terms of their environmental lifecycle impact reductions: Multi-family, ADU, and "Tiny Houses" 

Let's begin with the recent EPA-sponsored report about the energy impacts of residential housing choices. As stated on the introductory page, 

"Buildings and transportation together account for about 70 percent of energy use in the United States and are responsible for about 62 percent of U.S. greenhouse gas emissions"

The findings in this report illustrate that certifiably green buildings are not as significant in reducing that energy as where you build (Conventional Suburban Development or Transit Oriented Development) and the housing type (Single Family Detached, Single Family Attached, and Multi-Family). The report findings are summarized well in this rich graphic.

For me, I’m beholden to my innate desire to design and build something on my own terms. There are strong correlations between the size of average Single Family Detached, Single Family Attached, and Multi-Family homes. However, the impact of housing size perhaps has a more direct correlation to energy use than those building type descriptions.


From 1950, to 2008, the average sq ft per person has increased from 259 ft to 961 ft, a 372% increase. 

ADU’s are an accessible way for urban homeowners to make a big stand on issues that span community building, environmentalism, urbanism, and climate change. Done well, ADU’s present a compelling personal financial opportunity for individuals to create a regenerative, personal financial portfolio. I plan to discuss the economics of my ADU and ADUs at large in future posts. 



I have extracted some graphics from a presentation about the findings from the Oregon DEQ report, "Life Cycle Approach to Prioritizing Methods of Preventing Waste from the Residential Construction Sector in the State of Oregon". I anticipate this this groundbreaking report will prove to be pivotal in the green building movement and will help to instigate a shift toward an emphasis on living smaller. 

I believe ADU’s will naturally become more and more popular where there is sufficient housing demand and where they are allowed by zoning laws. With a few exceptions in the US, ADU’s are not legal.

The first ten minutes of this video is of Jay Shafer of Tumbleweed Tiny Houses addressing code barriers to small housing. Jay Shafer is the person who has popularized the notion of building tiny houses on wheels- which, as he explains, is simply a tactical exploitation of a common municipal zoning loophole to legitimize what would otherwise be illegally constructed tiny houses.

Inspired by the Doers

It feels quite remarkable and rare to have such easy and immediate access to innovative, creative, industrial minds all around me.

I met today with one of the authors of this Oregon DEQ report that found that the single most important variable to reduce the life cycle impact of residential construction is the size of the house. We discussed the smaller housing, ADU's, regulatory hurdles, costs, and material selection.

It was a great meeting of the minds, and I hope to continue to think through the overall strategy of this ADU with him further. He constructed a gorgeous, timber frame detached bedroom in SE Portland.

My girlfriend has lived in two cabins that she has renovated. Her cabin in Portland is a refurbished garage; while not a legal ADU, it is an ADU nonetheless. And, I might add, it the most gorgeous ADU I've seen to date. From the outside though, you would think it was just a plain garage. She renovated it on a budget of $20K. It seems me that a good rule of thumb may be that complying with building codes doubles the cost of design/build.

Two of her and my good friends in NE Portland are in the early stages of converting their garage to an ADU, though they are still trying to assess whether their $40K budget is sufficient for the job.

My mortgage broker has an ADU that she is renting out. She built it for $50K. My Realtor intends to build one over her garage. My "Phase I" builder is hoping to build one at him home in NE Portland down the road.

My architect took on the challenge of packing a lot of function into a small space with vigor. He was extremely knowledgeable and generous with his time. I have no doubt that he put more time into this design than he would on most projects, and for a relatively modest sum. I'd recommend him to anyone.

I am taking a class with Stephen Aiguier, the founder and president of Green Hammer. He is the most knowledgeable person I've met on green building issues. Incidentally, he seems to be increasingly focused on Passivehaus construction. What I respect most about Stephen is his deep understanding of building science, and his pragmatic and driven idealism. Learning from him is humbling.

My immediate neighbor is a craftsman and fabricator who specializes in reusing material, next door to me is the owner of a custom bicycle construction shop.

The ADU concept is ablaze in my circles in Portland. That is due in part to incredible range of needs and purposes that ADUs serve, but it is also a testament to the fact that here, in Portland, they are legal to build.

And that is rare. I'll discuss this much in more detail later.