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.

Tankless Water Heater for Radiant Heat

Thanks to everyone who came out to the ADU on the Build It Green tour. It was fun to be able to show off the place to so many people, and I hope that it left some of you all inspired to see more ADUs.

This post will deal with the tankless water heater and radiant heating, which I've mentioned in other posts, but never fully described.

An ADU water line splits off the water main in the main house basement, and comes to the ADU underground. Some of that (cold) water is directed to the water heater, which heats the water to ~120 degrees whenever we turn the hot water (for a shower, sink, dishwasher). The water heater is "tankless", which means that it heats up water "on demand", only when needed. A tankless, on-demand water heater is inherently is more energy efficient than a conventional 60-gallon holding tank water heater, which keeps 60 gallons of water heated constantly, even when there is no need for hot water.

Meanwhile, a heat exchange heats up more water in the heater in a separate "closed loop" to a lower heated temperature (~70-80 degrees) that runs through the Pex tubing throughout the first and second floors, providing in-floor radiant heat. Radiant in-floor, hydronic heat is the heat source, along with some passive solar heating.

There are three forms of heating: radiant, convective, and conductive heat. Most of us group these three forms together in our head as "heating", but they function totally differently from one another. 

Forced air is convective, and although it is the dominant mechanism used for residential heating in this country, it is not a good way to heat most residences. Radiant heat is generally the most comfortable and effective way to experience and manage heat. 

Radiant heats works totally differently than forced air heat.  Radiant floor heating will heat the surfaces in the house to a particular temperature (~70 degrees), and those surfaces will then radiate that heat outwards towards the occupants, reducing our body's heat loss towards those surfaces.

Radiant in-floor heating is a comfortable way to experience heat evenly throughout a home. Interestingly, with radiant surfaces everywhere, air temperature in a house can actually be lower than what you think is comfortable, and you will still feel warm. This is akin to when you're standing outside on a cold night, with your front side is facing a campfire. That's radiant heat gain working its magic on your front side, and radiant heat loss working on your back side.

Conversely, forced air heat does not heat up surfaces; it only heats the air that is then blown throughout the space, and air a poor heat conductor. That heat is quickly dissipated because air does not have the thermal mass to retain that heat. That energy that was used to heat that air is quickly dissipated and lost. The surfaces of the house will remain cool to the touch. Even if the air is warmed in a space, cold surfaces can still make you feel cold. Cooler surfaces draw heat from your body.

Houses heated by forced air tend to have spots that feel cold- areas far from the vents, or areas near cold surfaces like windows. While in the US, homes ares primarily heated using forced air (a form of convective heat), we are alone in this approach globally. Europe, for example, uses a far greater percentage of other heat types--primarily forms of radiant heat.

My water heater is a Navien condensing combi tankless water heater. It's gas powered, which is a more efficient way to heat water than heating with electricity, but both power sources are available as options for the tankless water heaters. Here's a video of the gas line from the street to the ADU, which is the gas supply that is used for both the water heater and for the gas powered cooking range.



Here's a video of the water heater. As you can see, the water heater plumbing and mechanics are a bit complicated. We'll use the radiant heating in the concrete slab on the first floor to heat the house. There are  radiant loops running through the second floor as well, but we will rarely use them. The concrete, once warmed, will easily heat the whole ADU in the winter. Once warm, it would take days for the concrete (and ADU) to cool back down. The heat demand load on this ADU will be very low, due the ADU's small size, the high R-values in the walls, ceilings, and floors, and the lack of thermal bridging. I'm looking forward to experiencing how the heat system works, and to comparing the gas bills from the ADU and the main house.

Come on the Build It Green Tour

Here was a little piece that KATU TV put on their local news program last night. It's a short and complimentary piece.

I tried several times to explain in pithy soundbites that what made this house green was the walkable, bikeable location, the small size, the air sealing, and insulation.

Instead, they showed close-ups of my kitchen sink and bathroom tiles while describing the "accessible dwelling unit". I find this funny because there is nothing really qualitatively "green" about the sink or tiles, other than being salvaged.

Oh well...this piece isn't really intended to truly convey what a "green" house is, but rather, to get more people to come on the tour. So, come on the tour this weekend and come check out the ADU and other great projects around Portland in person.

Sprinting to the Finish

We've moved in fully, so I wanted to give a tour of the finished product. There's some miscellaneous projects left to do, but for all intents and purposes, the interior of the ADU is complete. We've moved our stuff in, including furniture, decorations, and tons of other stuff.

Each time I move residences, I always groan at how much stuff I own, most of which I rarely use. This move was no exception. Except, this time, the limits of the small living space forced my partner and I to be more deliberate about deciding what items enter through these doors. Only the best of the best stuff gets through. Hopefully, we'll sell many of our remaining items this fall.

Part of the push to get fully moved in and decorated was in preparation for a news crew that used the ADU last week as their set. KATU, the local news station, came to film a short piece about the Build It Green Tour that will air on Tuesday, September 20th, at the 5 o'clock news hour. They said that they'd be posting the piece online afterwards; I'll link to it once it's posted.

KATU filmed a promotional piece for the Build It Green Tour

Here's a five minute walk through of the finished ADU. I am very happy at how everything is looking. It feels like a home now, and the most luxurious home in which I've ever dwelled. After a week, I can say that I love being in this space.



Meanwhile, I've decided to rent out the main house as a fully furnished, self-hosted, Bed and Breakfast on AirBNB. I am going to give this a try for a month or two to see whether it works better than a normal long term rental. It's a great house for groups of 4-10 who are coming to visit Portland and would prefer to stay in a sweet old house for less than staying in a hotel.

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 

Artistic Images of the Finished Interior

Over the weekend, we put many finishing touches the ADU. It's now "move in" ready. We expect for it to pass the final inspection this week. Here are some images of the ADU. I got carried away.