Inhabited Mobile Dwellings Survey 2024 (Cully Neighborhood, Portland, Oregon)

Four years ago, in June, 2020, I conducted the inaugural study of the rate of inhabited mobile dwellings on residential properties in the Cully neighborhood in Portland, Oregon. 

This study laid the groundwork for a follow-up survey I conducted four years later, which used the same parameters and methods. The decision to revisit this survey was influenced by a significant policy change in April, 2021, when Portland legalized recreational vehicles as a form of housing in residential areas.

Previously, residing in mobile dwellings was part of an informal market, but it was suddenly recognized as a legal housing type. This transition, happening just a year after my initial survey, offered a unique opportunity to observe how legalizing this once-informal housing option would affect its usage over time.

Review the initial survey post for extensive description of the survey methodology and neighborhood context, which I will not repeat here. It’s worth reviewing the methodology if you’re interested in this research, as well as the additional notes toward the end of this post. 

In this post, I’ll use the shorthand “RV” for a recreational vehicle, and “THOW” for a tiny house on wheels. Together, I refer to them as “mobile dwellings”. 

Now, let’s dive into the findings and analysis of this new survey. 

A map of the locations on inhabited mobile dwellings in the Cully neighborhood in April, 2024

Here’s a link to the photo album of each of the 94 properties that I identified in 2024. (It is difficult to make out the mobile dwellings in some of the images. They’re often discreetly located or obscured by trees.) 

The photo album of the 94 properties

2024 Survey Findings

There were 94 residential properties with either an occupied RV or an occupied THOW in the Cully neighborhood.

This increase of mobile dwellings used as occupied housing was substantial – a 45% increase from 2020 to 2024. 

The breakdown of inhabited RVs vs THOWs in 2020 and 2024 respectively was:

	2020	2024
RVs	36 (or 55%)	45 (or 48%)
THOWs	29 (or 45%)	49 (or 52%)
TOTAL	65	94

Of the 65 properties that had mobile dwellings in 2020, 17 of them no longer had mobile dwellings on them in 2024. The other 48 still did.

46 of the 94 host properties in the 2024 survey – nearly half of all properties – were therefore new land hosts to mobile dwellings. 

At least seven sites of the 94 that I identified had two or more inhabited RVs – for the purposes of this survey, I counted these as “1” site.

Analysis of Findings

The growth of mobile dwellings being occupied as housing appears to be very significant since the prior survey

The number of residential properties in Cully that had an occupied mobile dwelling increased from 1.6% to 2.3%.

Inhabited Mobile Dwellings in 2020	Inhabited Mobile Dwellings in 2024

In Cully, the total final ADU count increased from 106 to 119 (12% overall) from 2020 to 2024. However, inhabited mobile dwellings in Cully increased by 45% over that same time period.

Here’s an image of the 94 properties with inhabited mobile dwellings, overlaid alongside the 119 properties with permitted ADUs.

As with ADUs, the absolute numbers for properties with inhabited mobile dwellings remains fairly small. But it’s clear that this form of residential infill housing is experiencing rapid adoption relative to other common housing types. This notable increase is certainly attributable to Portland zoning changes in 2021, which legalized their habitation on residential properties.   

A shift towards THOWs instead of RVs

There was a 7% shift towards using THOWs instead of conventional RVs as housing. 

I’ll also note here that in our general contracting work installing RV hookups on residential properties over the last 2+ years, the vast majority of our installations have been for tiny houses on wheels. 

To add a little bit of color to this trend, it is reasonable to hypothesize that the legal formalization of this mobile housing option has possibly bolstered homeowner confidence to “invest” in a higher quality, more expensive RV (such as a custom-built THOW) rather than using a cheaper RV option. 

An inhabited RV	An inhabited THOW

You’d never even know that some of these were actually mobile dwellings

You would never know there was a THOW in the image below. But, I happened to install the RV hookups for this project, so I know that this light blue building in the center of the image is a THOW with skirting that hides the wheels, even though it appears to be a home on a foundation. 

This dwelling is lived in by an extended family member of the primary house, which is the case for most of the RV hookups that we’ve done. 

Mobile dwellings come and go 

Here’s an example of property that used to have a THOW but no longer does. This housing form separates ownership and utility of the dwelling from the primary home, allowing for housing to be used when needed and where it is needed. 

Property in 2020	Property in 2024

In this case, the THOW has apparently rolled along to greener pastures.

Of the 65 properties that had mobile dwellings in 2020, 17 (or 26%) of them no longer had mobile dwellings on them in 2024. 

The innocuous infrastructural RV hookups for a tiny house that used to be parked here: A spigot, and a power post. 

Of course, if the current property (a.k.a- land host) wanted or needed an instant backyard housing option again, they could likely do so, given that they had the capacity to do so in 2020.

This potential for dwelling transience is one of the defining attributes that makes this form of mobile housing extremely different from conventional housing on foundations, for RV owners, land hosts, and businesses alike. 

The other factor that is extremely different from conventional housing is the relatively low cost to get the proper setup for a mobile dwelling installed on a property. 

Given the inherently low cost (generally ~$10K or so) for installing RV hookups, there’s comparatively little investment or economic motivation for a homeowner to actually use the space for a dwelling if they lose their motivation or need to do so. The going rate for renting out an RV pad with hookups in Portland (at the time this post was published) is $500-800/month. 

By contrast, if a homeowner built a $225K ADU (the average all-in cost for a 400 sq ft ADU), they would be economically motivated to keep generating income from the unit on a full-time basis for 6-10 years to pay off the initial cost of development, or to at least defray the cost of the loan that they used to build it. 

Market demand for mobile dwelling clusters in spite of the regulations

At least seven sites of the 94 that I identified had two or more inhabited RVs. 

For purposes of this site survey, I counted these locations as “1” site, but if we count them on their own, it means there were actually closer to 101 inhabited mobile dwellings on the 94 sites.

Interestingly, inhabiting multiple RVs on a residential property is not allowed by Portland. However, in my decade-long experience working directly in this field with tiny house dwellers, it is obvious to me that there is very significant demand to live in “tiny house communities”. 

The reason that Portland does not allow multiple inhabited RVs on residential properties is that two or more RVs on a single tax lot are considered to be an RV park under Oregon law. RV parks are only allowed in zones in Portland that authorize a “Residential Manufactured Dwelling Park”, which are very limited. 

Incidentally, the Cully neighborhood DOES have legacy, legal RV parks, which have many permanently occupied RVs in these zoned areas. 

Example of one RV park in the Cully Neighborhood

One shining example of the market viability of a tiny house community is Tiny Tranquility, located along the coast in Waldport, Oregon. It is fully occupied and has a wait list.

Image from Tinytranquility.com 

Similarly, there appear to be only a handful of RV parks in Portland. Of those that exist, the long-term rental spots are largely taken. I have observed that RV parks are generally in short supply in areas where land values are high, whereas there are plentiful RV parks in more rural (and less expensive) areas. 

To fix the mismatch between the demand for this obvious affordable housing solution for high value urbanized areas, and the lack of legal means to achieve it, there are two zoning fixes that come to mind. 

First, there is nothing in state law precluding Portland or other cities from changing their zoning to allow RV parks more broadly in Residential zones rather than limiting RVs parks solely to Residential Manufactured Dwelling Park zones. 

Second, the State of Oregon could update its law from stipulating that RV parks are 6 or more RVs on a tax lot, rather than 2 or more. 

Then, Oregon cities would be able to alter their ordinances to allow up to 6 RVs on a residential property without calling it an “RV park”. 

In this case, much like manufactured homes can be used to create a “cottage cluster” under Oregon state law, RVs could be classified as an alternative option for creating a “mobile cottage cluster” in residential zones. 

From Oregon’s HB 2001 Interpretation and Implementation FAQs

Neither of these two options are especially complicated or controversial. My experience is that there simply seems to be a lack of interest on the City’s part to engage on these mobile dwelling zoning solutions. 

This is terribly ironic, given the amount of political attention and capital that the City of Portland and State of Oregon are allocating to “affordable housing” solutions that now cost well north of $400,000 per door to develop. 

Legislative analysis

The reality is that RVs are already used as informal housing all over the country. This is especially true in lower-cost rural areas, but also true in cities. People create their own affordable housing solutions whether or not it is legal for them to do so.

Informal ADUs long preceded the contemporary ADU movement. It is by recognizing, legalizing, and daylighting ADUs into an accepted form of housing that we were able to foster an ADU explosion, at least on the West Coast. 

Similarly, RVs appear to be another example of a housing solution “desire path”; RVs are already the solution that average people are using to meet their housing needs. Rather than using a top-down approach to creating more affordable housing, it makes more fiscal and political sense to simply scale up this existing bottom-up approach to housing. 

Oregon law allows for RVs to be used as legal housing in manufactured home parks. What is necessary is simply to expand the entitlement of where RVs can be used as housing to all residential zones. This particular solution is not that hard, actually, as Portland has now proven.

Methodology Notes

This survey method of the 4,000 properties in the Cully neighborhood was a bit time-intensive and required expertise with recognizing this housing type, but there’s no other way to conduct this survey. 

For example, none of Google aerial imagery, Google Street View imagery, or any type of GIS analysis could provide much value in this type of survey.

There are no building permits for these dwellings. Instead, only trade permits for the hookups on the property are required, and there’s no mechanism to track those permits. And, even if there were such a mechanism, the presence of RV hookups does not indicate there would actually be an inhabited mobile dwelling located along with them (see section above Mobile dwellings come and go).

Instead, it required literally peering over fences on my tiptoes from the street, viewing backyards from strange angles, and walking down shared driveways, to catch glimpses of the tops of these dwellings in many cases as you can see from the full photo gallery. 

A shared private driveway that leads to another property, where a tiny house on wheels is parked.  Google Street view data doesn’t collect images from private driveways. See THOW in yellow box below. 

Using aerial imagery, a THOW is essentially indistinguishable from sheds and other accessory structures. 

In other words, AI can’t do this survey. 

Take that, AI. You are not my overlord.

A Request for Additional Qualitative Research on Mobile Dwellings on Residential Properties

While this type of drive-by survey is informative, it also has major limitations. It inherently lacks the ability to penetrate into the qualitative variables involved in this housing choice for both the land host and mobile dwelling occupant. 

• What motivated the owner to have a mobile dwelling on the property?
• What’s the relationship between the mobile dwelling occupant and the primary home occupant?
• Is this form of dwelling satisfactory for the occupant?
• Who owns the RV? 

There’s also many quantitative variables that it can’t address. 

• How much does the occupant of the RV pay to live there? 
• How long have they lived there? 
• What are the age and economic profiles of the occupants?
• How many vehicles are added as a result of the new occupants living in the RV?

A deeper study will require funding, or bootstrapped doctoral thesis research. If you are interested in funding additional research on this topic, or you are an academic who would like to conduct formal research to answer some of these questions, please reach out to me. I’ll share the granular locational data with those who intend to further this foundational research.