Rate of Inhabited Mobile Dwellings on Residential Properties in One Portland Neighborhood

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Map of inhabited mobile dwellings on residential properties in the Cully neighborhood, Portland, Oregon. June, 2020

Executive Summary 

In June, 2020, I conducted some voluntary research to determine how many single family residential properties had an inhabited mobile dwelling. I used my own neighborhood, Cully neighborhood in NE Portland, Oregon, as the formally defined boundary of my study geography. I then proceeded to ride by bike, and assess every single family residential property to determine whether there was an inhabited mobile dwelling or not to the best of my ability. 

The Cully neighborhood consists of 12,595 residents, or 4,685 households. The majority of this neighborhood is residential, though there are some commercial, light, and even heavy industrial areas.

My survey found 65 inhabited mobile dwellings located on residentially zoned lots. 

I surveyed the mobile dwellings by type: recreation vehicle (RV) and tiny house on wheels (THOW). Of the 65 mobile dwellings, my survey found the following numbers of properties with:

• Inhabited RVs: 36
• Inhabited THOWs: 29

Given the 65 inhabited mobile dwellings, this gives us a density rate of 0.005 mobile dwellers on residential properties per resident.

Given the population of Cully neighborhood, it would therefore be reasonable to extrapolate that there are 3,273 inhabited mobile dwellings in Portland (0.005 x 654,741). 

Notably, based on an extrapolation of the rate of inhabited mobile dwellings found by this survey, the number inhabited mobile dwellings on residential properties (3,273) exceeds the number of permitted ADUs in Portland, which number roughly 3,139.

Here’s an album of images of the inhabited mobile dwellings found in my survey. 

Policy Overview

This housing type is unsubsidized, market-rate, and ultra-affordable housing stock. This ‘ultra-affordability’ is because there’s no land cost associated with these dwellings and because the dwellings are extraordinarily inexpensive relative to conventional housing structures, such as primary homes or ADUs.  

Let’s quickly review some of the questions and critiques that policy makers may have about this ultra-affordable market rate housing option. 

• Are they as safe or built to the same standard as permitted structures? No. 
• Are these housing options safer or better than living in a tent on the sidewalk or informal encampments (ie. tent dwellers living together under an overpass)? Yes, inhabited mobile dwellings on residential properties are safer and preferable to living in tents or mobile dwellings on public rights of way.  
• Are mobile dwellings on residential properties a way to address homelessness or does it solely address voluntarily tiny living? Both. More research is needed to be certain, but my survey indicates that the likely cost range for residing in these dwellings would be from free or ultra-affordable, to low-cost market rate affordability options. 
• Why not just continue to have people living mobile dwellings in public rights of way? We should. But, there are vast numbers of private property owners that would be willing and able to provide ultra-affordable market rate housing options on their private property in the form of mobile dwellings, or simply renting out space for them. And, more importantly, on residential properties, the mobile dwellers can have access to safe, protected spaces, residential zone lifestyle space amenities (eg. outdoor space), and better health and sanitation amenities (eg. RV sewer hookup), rather than solely dwelling on public rights of way, or other uninvited private land squatting encampments. 

The low-cost market rate for living in a mobile dwelling on a residential property would be roughly equivalent to the rental price of the lower end of the cost spectrum of an informal ADU. 

Despite the need for lower cost, market rate, affordable housing options, mobile dwelling options have not been investigated with much rigor, nor its potential explored. The zoning code does not facilitate, let alone promote, this housing alternative. 

And yet, my preliminary survey research indicates that this is a singularly untapped and underutilized housing alternative, through which vast potential exists for ultra-affordable and decent housing options in Portland. 

In other words, the regulatory abolishment of this housing option, whether implicit or accidental, is nonetheless a choice that Cities have made. 

At best, it ignores and does not promote this housing option. This aversion explicitly and directly contributes to unhoused populations sleeping in less safe, unharbored, unprotected, and non-sanitary conditions throughout forgotten, blighted, and ignored fragments of public land where homeless tend to reside today—under bridges, under store awnings, in parks and parklets, on sidewalks, and on urban streets throughout most major US cities. 

About Inhabited Mobile Dwellings

To my surprise, inhabited RVs outnumbered inhabited tiny homes on wheels in my survey. 

• 55% of the inhabited mobile dwellings were RVs (ie. motorized RVs or travel trailers). 
• 45% of the inhabited mobile dwellings were tiny houses on wheels (ie. wood clad, typically custom built mobile dwellings on chasses). 

The ‘tiny house movement’, which has been growing in prominence since roughly 2010, and even more recently, the #vanlife movement, have brought a new demographic to inhabiting mobile dwellings as a lifestyle choice. It has also aesthetically overhauled small housing with novel space-efficient technology-based solutions and spurred new communities of practices (eg. Forums, Facebook groups, blogs, YouTube channels) which have accelerated and democratized the transfer of knowledge among practitioners and dwellers alike. I contend that these advancements are also rapidly exceeding the rate of technological advancement in common single family home construction methods.  

Nonetheless, despite the pop-culture popularity of tiny homes and vanlife, my survey indicated that inhabited RVs still play an equal or slightly dominant role in terms of providing informal housing in mobile dwellings on residential properties. 

“The economy, stupid” 

• James Carville, 1992.

Given the tremendous pop-culture exposure of THOWs, why are RVs still more dominant?

Used travel trailers and RVs for under $10K are abundant in every US market on Craigslist, including Portland. An average price for a custom-built tiny house on wheels is $50K. 

I assume that the substantially lower cost of used RVs is the primary reason they’re more commonly being used as dwellings on residential properties than custom built tiny homes on wheels in my survey area. 

This is also why I’ve opted to include both dwelling types in this survey and have explicitly grouped them together under the term, “inhabited mobile dwellings”, rather than calling them “tiny house dwellers”, or “RV dwellers”, or some other term that would limit what type of creative mobile dwellings (eg. skoolies) could be considered a viable housing option. 

Methodology 

Here was the method I used for determining whether a mobile dwelling on a residential property was inhabited or not. If there was a permanent plumbing sewer connection, I classified it as inhabited. Other than that particular signal of habitation, I would seek several indications of habitation in order to classify it as inhabited. Those indications of habitation included opened retractable awnings and opened RV extension/pop-out components, home curtains drawn, an active electric connection, stairs leading to RV, and furniture set up around the entryway of the mobile dwelling. There were far more non-inhabited RVs than inhabited RVs. I did not count uninhabited RVs in my survey 

This survey mythology is not perfect. A perfect methodology would actually confirm whether these dwellings were inhabited. A perfect methodology would do a more thorough site survey as well- I wasn’t able to see behind homes, for example. 

As a practical matter for the findings of this survey, I’ll rationalize my imperfect methodology as follows. 

I have an atypically well-trained professional eye for this discreet housing type, so if anyone could spot hidden but inhabited mobile dwellings tucked away behind garages on residential properties, it would be me. But, I definitely missed some of the mobile dwellings that I could not see from the street or other public rights of way. I would guess that I missed 10-15% of the mobile dwellings, in part due to deep lot configurations. 

Here’s an image of a property that I know to have a mobile dwelling behind the primary home shown on the right side of this image, but the THOW is not visible from the street. I counted this particular property in my survey, but this is an example of a situation in which I would have certainly not counted this property in my survey of inhabited mobile dwellings, had I not had first-hand knowledge of the dwelling through my personal network.

Conversely, I likely included a number of inhabited mobile dwellings that weren’t actually inhabited. For sake of this ‘informal’ research, let’s say that I overcounted the actual number of inhabited vehicles by 15%.

It would be a safe assumption that I actually missed more of the inhabited mobile dwellings altogether than the collective number of mobile dwellings that I counted as inhabited, that actually weren’t. For simplicity’s sake then, let’s just have those two assumptions of manual error, cancel each other out. That’s a fair trade, and it certainly makes the math easier 🙂

Images of inhabited vs non-inhabited RV, to show survey methodology

Here’s an inhabited RV, which I classified as such due the extended pop-out component of the RV, the drawn custom curtains, the retracted step, and the electrical connection. 

Here’s a non-inhabited RV. It did not show any of the indications of habitation listed above, so I assumed it was simply an RV being stored, rather than actively used.

Status of Inhabited Vehicles and RVs on Public Rights of Way

Here’s some inhabited RVs on public, commercially zoned street ways in the heart of the Cully neighborhood. Officially, this habitation of vehicles and RVs is forbidden under current regulations on public rights of way. But, in practice, there’s kind of an implicit acceptance that RV habitation, really anywhere in Portland, is more or less condoned in light of the declared housing emergency, whether it’s formally allowed or not. This is, in fact, a quite common phenomenon in Portland.

One estimate from a staff person who works at a homeless support organization called StreetRoots, guessed that 20% of homeless in Portland live in vehicles or RVs such as those shown above. These individual mobile dwelling occupants could be classified as ‘secret homeless’ or ‘stealth homeless’. I’m speculating here, but this is likely a transitional sheltering option for many people first moving out from a more formalized housing due to life circumstances. 

Cully Neighborhood

Here’s an image showing the Cully neighborhood, one of Portland’s 94 neighborhoods. Cully had a population size of 12,959 in 2000.

Comparison of Inhabited Mobile Dwellings to the Distribution of Permitted ADUs in Cully: Uncanny Coincidences

Now, let’s make some observations about permitted ADUs to inhabited mobile dwellings. When comparing the geographic and numeric distribution of inhabited mobile dwellings to permitted ADUs in Cully, to the geographic and numeric distribution of inhabited mobile dwellings on residential properties, a couple of things popped out. 

The map above shows ADUs as blue dots, and inhabited mobile dwellings as little circle images, in the Cully neighborhood, which is the area shown in green.

There is a geographic and numeric distribution correlation of inhabited mobile dwellings and ADUs, down to the block level. 

I’m not sure what to make of this. Is it sheerly just a coincidence? Or, maybe I’m exaggerating this observed geographic clustering correlation altogether? You can look at the map above and decide whether there’s a significant or non-significant geographic clustering correlation for yourself.  

If there is actually a geographic correlation, why might this be? Do certain blocks culturally attract, or organically foster, these forms of secondary housing development, informal and formal alike, while other blocks do not? Or, do certain blocks have larger or oddly shaped lot configurations that generally lend themselves more so to secondary dwellings, whether they’re mobile or fixed?

The number of ADUs and inhabited mobile dwellings is also very close. Indeed, the number of permitted ADUs in Cully as of 2020 was 60. I’m a bit baffled by this one as well. Again, is this just sheerly a coincidence? I welcome theories. But, only more surveys like this one would provide a more defensible reasoning of whether there’s any numeric correlation in general between inhabited mobile dwellings and ADUs. 

Cully is ‘friendly’ to inhabited mobile dwellings

The number of inhabited mobile dwellings on residential properties was 65. So, in this particular neighborhood, there’s actually slightly more inhabited mobile dwellings than there are permitted ADUs (ie. 60).

It’s likely that Cully as a neighborhood has a disproportionately high number of inhabited mobile dwellings on residential properties. If Portland is sometimes thought of as a ‘tiny house capital’, Cully may be understood as one of the most ‘popularly settled’ neighborhoods of Portland in terms of mobile dwellings on residential properties.

They’re neither ubiquitous or in your face, but for those who are involved in the culture of the tiny house movement in Portland would likely concur that Cully is especially ‘tiny house friendly’.  Even so, most Cully residents would be unaware that their neighborhood would be thought of as a ‘center of tiny house activity’. Indeed, neighbors may have never seen or noticed any examples of them in the neighborhood, as they blend in pretty seamlessly to the native architectural fabric of the neighborhood. 

But, let me take a moment to enumerate an ill-defined notion of why the Cully neighborhood may be thought of as tiny house friendly. 

Cully is located on the outer edge of older central city neighborhoods of Portland. It has larger and unusual lots due its history of being platted from fruit orchards and only being annexed into the City-proper in the 1990s. It has smaller-than-average cottage homes, many of which were built in the early to mid-1900s. There are odd and deep lot configurations, rural-feeling unimproved streets. 

The land has slightly lower costs than neighborhoods to its west. It’s slightly on the funky side, with a light-industrial zoned area, homelessness, a strip club, mixed in with an almost ‘rural feeling’ set of urban values that are evident in yards and streets in the neighborhood: homesteading, CSAs, cyclists, and lots of home and vehicle repair DIY-ing. Many of the roads have no sidewalks, so the pedestrian and cyclist activity is intermixed with vehicles on the streets. 

To augment those rural-feeling attributes, Cully is also home to an outsized share of permanent mobile home parks. Notably, I did not count any of the inhabited mobile dwellings in the mobile home parks as they were not the subject of my survey research of residential properties. Mobile dwelling in mobile home parks would have added 100-200 to the count. This means that formal mobile dwellings (ie. manufactured home and mobile homes) are relatively common and are part of the ethos of Cully. 

And based on some combination of those factors, parts of this neighborhood seem to naturally lend themselves to homeowners including mobile dwellings on their property, and maybe why Cully could be considered ‘tiny house friendly’. 

Conclusion

Regardless of whether this particular neighborhood is especially ‘tiny house friendly’ or not, this survey indicates that the utilization of this housing form is potentially fairly common, or as commonplace as ADUs anyhow. And this is despite the fact they are inhabited under a only tenuous and temporary amnesty declaration, rather than being a formally permissible housing option, a status conferred to ADUs for decades.

Cities that are experiencing an affordable housing crisis should investigate the residential market potential that this flexible housing type singularly offers as a completely viable and simple way to add ultra affordable market rate housing. This housing type is already being used, and as long as it is criminalized, it is eliminating the viability of this untapped market. Furthermore, criminalization of the habitation of mobile dwellings on residential properties exacerbates the likelihood that the occupants will end up unhoused and unsheltered on the streets, sidewalks, and other fragments of underused urban lands.

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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