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One Year In, Are Tiny Houses on Wheels the New ADU in Portland?

Introduction 

My friend and I are one year into installing RV hookup infrastructure on residential properties in Portland for homeowners who are adding a mobile dwelling. We do this work through a general contracting company called Tiny Hookups LLC. This company was formed on the heels of the legalization of RVs (and tiny houses on wheels, which are classified as RVs under Oregon state law) as a legal dwelling option in Portland, Oregon, in 2021

This was a new endeavor that we started as a passion project. We didn’t aspire to make a lot of money, nor grow the company, and we actually only ever planned to run the company for two years.  Indeed, we still plan to sunset the company in a about a year, and furthermore, we hope to catalyze competition so that our company becomes irrelevant.

How’s that for a bold company vision statement!

My motivation for starting this company was to get a grounded basis for viscerally understanding the best practices for installing RV hookups on residential properties, the pros and cons of RVs vs ADUs as housing options, and also to gain some real life experience as a general contractor. 

Costs of the Projects

This post covers the cost aspects of this RV hookup work. Since I know that the low costs are why this type of housing is so compelling and the key differentiator between it and other forms of affordable housing, I wanted to share some intel about these costs. This post is intended to provide first-hand proof (with receipts to prove it) that this is the least expensive legal housing type available in a residential zone any city in the United States. 

By way of context, it is important to know that ‘Affordable housing’ in Portland as of 2022 costs approximately $400K per unit.

As I show in this post, these RV market rate housing solutions can cost as little as $20K, which is 1/20th of that $400K conventional “Affordable housing” development cost.

And, this approach is relying on for profit, market-based housing development, totally unsubsidized with no governmental help whatsoever, beyond relaxing the residential zoning code to allow it to occur.

In our initial $100 informational consultations, we tell our clients and even encourage them, to manage the projects themselves to save money. But, some homeowners prefer to have professionals perform the work because they simply don’t have the knowledge, time, or ability to manage the process themselves. Also, we guarantee that we will do the work the correct way, legally, with permits.  

The costs described below are the costs to our clients, after we build in our oversight, administrative costs, project management, and the site prep work. The costs and bids listed below include our profit. A homeowner could self-manage these projects, and do them for less than the costs listed below, sometimes much less.

These infrastructural connection costs vary a little bit, but this is usually a good starting point for us to provide an estimate. 

  • Sewer extension work- $3.6K
  • Water service extension and heated yard hydrants- $3K 
  • Electrical circuit and RV panel installation- $3.2K
  • Gravel pad- $3.5K for 25ft x 10ft parking pad

If we do all four of those services for them, that comes out to $13.3K.

I’ve attached three of our recent estimates as a visual reference of how these costs break down in some real life projects we’ve done in the last year. 




Here’s an example of the plumbing trade permit that we needed to obtain for one job, which cost $204. These trade permits are issued same day and extremely simple to obtain. No building permit is required, since the dwelling itself is not subject to inspection. Only the hookup infrastructure that our company installs is actually inspected to ensure that it complies with building codes.

The utility extension work involved has triggered additional infrastructural upgrade work to the primary dwelling on most projects that we’ve done. And, these utility upgrades to the primary house typically make the projects more expensive. Notably, these upgrades are things that a homeowner should probably do for the durability of their primary houses in most cases, independent of the RV hookup work. It’s just that during our initial assessments, we ‘discover’ these latent infrastructural issues for them.

These are the same types of utility upgrades that would occur if someone is adding a detached ADU to the property. For example, the sewer has a ‘belly’ due to the dirt under the sewer pipe settling over time, so blackwater is pooling up in their sewer and therefor the sewer needs to be redone; the lateral water connection line from the meter has a corroded galvanized steel and needs to converted to PEX before a plumber will touch it; the electric service is only 100 amps, and the electrician can’t add a new 50 amp circuit till it’s upgraded to 200 amps. 

Here are some of our typical costs for that work additional work. 

  • Electrical service panel upgrade- $4K
  • Electrical total package ($8K for new panel, service upgrade, new masthead, meter) 
  • Water service upgrade – $2.5K
  • Adding a dedicated ethernet service for the tiny house- $600

There’s other wildcard variables for each lot, ranging from garage demo, tree removal, septic tank demo, sewer lateral replacement, which cost varying amounts. Our hookup projects have tended to be about $15K, after all is said and done, due to the upgrades and wildcards.  But, they’ve been as low as $5K and as much as $25K. 

Here’s an album of some of the project work.

Notably, these aren’t glamorous shots. Our RV hookup work is precisely the opposite of glamorous work. 

Other Observations About RVs as Housing

Time to Deploy: The work itself typically takes about 2-3 weeks to do, but it takes quite a bit of planning and coordination to get the work lined up. So, we tend to plan out 2-3 months in order to get all of the contractors’ schedules aligned. But, notably, the site work and the tiny house construction can take place concurrently in different locations, and this has happened with half of the sites where we’ve installed infrastructure. Also, as noted above, the permits for this type of housing are inexpensive and can be obtained on the same day without any delays since the site work electrical and plumbing hookup connections are all that are inspected.

Housing quality: Our business has nothing to do with the actual dwellings and whatever the homeowner wants to install is up to them. We just provide the infrastructural RV hookups and are impartial about what mobile dwelling they opt to use, although we also help them connect their mobile dwelling to the hookups that we install if they would like our assistance with that work.

Like everything else, the costs and quality of these dwellings can range tremendously. The RVs and tiny houses themselves have varied quite a bit in terms of their quality, charm, and livability. The least expensive of them was an old 27ft RV that cost the homeowner $6K, but required some additional internal plumbing work to get it up to livable standards. Look on any Craigslist in the country, and you can find used RVs with a kitchen and bathroom for under $10K. The most expensive dwelling was a $140K tiny house on wheels.

Recently, we’ve had a couple of clients who are buying and installing larger RVs called Park Model RVs, such as this 384 sq ft park model, which is costing her $55K after adding in transport and other optional upgrades to the $45K base price. I’ve been involved in the sale of three tiny charming, but used, 120-160 sq ft tiny houses on wheels in the past six months for $30K, $42.5 and $45K, respectively. These days, $50K seems to be reasonable budget for a custom, used tiny house on wheels or a vintage Airstream. A custom, new tiny house or fancy new RV can cost closer to $100K.

Who Are RVs Serving: So far, 2/3rds of our (10 or so) clients have been installing RV hookups for family members (typically, moms, dads, or siblings). The family members are typically paying for the hookup work to be done by us, and buying their own RVs and THOWs from other entities. 1/3rd of our clients are installing an RV hookup for rental income purposes. All of them have had a particular mobile dwelling in mind by the time we have installed the hookups for them. Both the $6k and $140K example above, were used for an older parent who has relocated to Portland to live with their adult child.

Given the escalating costs of construction for both material and labor, I’ve been calling THOWs the ‘new ADU’ in Portland. They seem to be functionally filling the housing role that ADUs played in this market ten years ago, emerging as a new attainable, market rate, grassroots housing development option.

Our homeowner clients, and the mobile dwellers, seem to be totally satisfied with this housing option, given the comparatively modest costs involved in getting them set up compared to having an ADU built.

If the costs and level of complexity involved were the same, these clients may have gone for an ADU over an RV. But, they aren’t nearly the same. These days in Portland, an 384 sq ft custom ADU would cost $225K on average and takes a year to develop.

Unlike ADUs, RVs are treated as a personal asset just like any other vehicle, and can be liquidated and bought, sold, and traded. Along with lower cost, this lifestyle flexibility and financial flexibility is the key differentiator, making RVs and tiny houses into a killer app that runs circles around conventional housing.

RVs and tiny houses are like Spotify is to music. ADUs are more like a record player. Some people prefer record players for the acoustic quality, but Spotify is way better if you’re just trying to listen to music.


Of course, these dwellings are indeed ‘tiny’, so they aren’t for everyone.

Entrepreneurially speaking: After one year of working in this capacity, in addition to the hookup work that we do, I can see that there’s ample room for other small business pioneers. There’s a number of interesting side hustles and new small business specialty needs for this sector of housing, including building tiny houses themselves, tiny house inspections, and tiny house and RV repairs.

Simply moving and placing the 8,000 pound tiny houses on a residential site is a specialized job that can cost $500-$5,000, depending on how far the dwelling is being delivered. A professional tiny house mover we work with regularly, estimates that he’s moved 40 THOWs in the last year at an average cost of $600 per move.

Policy: My hope is that we can start to study this form of housing to see how it’s actually working in terms for both people who have them and live in them, akin to what we did with ADUs via a formal study of them in Oregon in 2014. This survey and research turned out to be pivotal in the early days of ADU movement a decade ago.

Park Models RVs are an especially interesting hybrid type of housing that falls somewhere between RVs and HUD Manufactured Homes that definitely merits more policy attention for those who care about enabling affordable housing solutions. They may offer a housing policy middle ground that won’t cause as much heartburn for anxious policy makers and building code bureaucrats. Park Models RVs are actually allowed as type of detached ADU in various markets in California, but notably, they are not being developed as ADUs to the same degree that RVs are being adopted in Portland. This delta in rate of utilization merits research, but that research would require jurisdictional permitting data about how many of these dwellings are being developed.

Which brings me to my final point…

Amazingly to me, the City of Portland is completely clueless in terms of how many people are adding these RV hookups to their property. They don’t have any way to track these hookup installations in their permitting database. This is laughable, because they have actually stumbled upon a means to provide the most affordable housing type in the country, as I’ve laid out in this post. Given the housing affordability crisis that the entire country seems to be facing since COVID, it’s ironic that the City of Portland itself has not yet taken notice that they have actually fumbled their way into potentially solving the housing crisis, if only they cared to realize it. 

About Kol Peterson

Kol is an ADU consultant, advocate and author of Backdoor Revolution: The Definitive Guide to ADU Development. Read more here: AccessoryDwellingStrategies.com and learn about building your own at BuildingAnADU.com. Email at Kol@accessorydwellingstrategies.com

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This entry was posted on January 11, 2023 by in 399 SF or Smaller, Policy & Trends and tagged .

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