A few years ago, if you owned a house on a regular residential lot in Portland, that's pretty much all you could have there. One house, one family. That's changed in a big way, and I think a lot of homeowners and investors still haven't caught up to what's possible now.
What changed
Two big things happened.
Portland's Residential Infill Project (passed in 2020) opened up most of the city's former single-family zones to duplexes, triplexes, and fourplexes. On a lot of standard residential lots, you can now build more than one home.
Oregon's middle housing law (House Bill 2001, passed in 2019) required larger cities across the state, including the Portland metro, to allow the same kinds of "middle housing" in neighborhoods that used to be single-family only. So this isn't just a Portland thing, the rules apply in a lot of the suburbs too (each city has its own specific standards).
And on top of that, ADUs (accessory dwelling units, like a backyard cottage, a converted garage, or a basement apartment) are allowed on most residential lots in Portland, and you can often have up to two.
Why this matters for homeowners
If you already own a home, especially one you bought with a low rate, an ADU can be a way to:
- Generate rental income to help offset your mortgage.
- House family, like aging parents or adult kids, while keeping everyone's independence.
- Add value to your property by creating a second livable unit.
- Stay put instead of selling and giving up your low rate.
Why this matters for investors
For investors, middle housing opens the door to strategies that weren't possible before. You can buy an older home on a large lot, keep the house, and add units. Or you can buy a property with an existing house and an underused backyard and build a detached ADU. More units on the same piece of land means more rent from the same land cost.
A big incentive right now
Here's the part that's very timely. To encourage more housing, the City of Portland is temporarily waiving system development charges (SDCs, one-time fees the city charges on new construction to pay for things like sewers, water, parks, and roads) on most newly created housing units. The building permit has to be issued between August 15, 2025 and September 30, 2028, and you have to hit certain construction milestones within a year of getting the permit. SDCs can add up to thousands or even tens of thousands of dollars per unit, so this is real money!
ADUs aren't part of that particular exemption, but they have their own separate SDC waiver program you can apply for. Either way, if you've been thinking about adding units, the next couple of years are a good window to do it.
How to pay for it
This is where I come in, and there are a few different ways to finance an ADU or middle housing project:
- HELOC (home equity line of credit). If you have a low first mortgage rate you want to keep, a HELOC lets you borrow against your equity without touching that first loan. The rate is usually variable and higher than a first mortgage, but you only pay interest on what you've drawn.
- Home equity loan. Similar idea, but a fixed amount at a fixed rate.
- Cash-out refinance. This replaces your current mortgage with a bigger one. At today's rates, it usually only makes sense if your current rate is already close to market rate.
- Renovation loans. Programs like Fannie Mae's HomeStyle and FHA's 203(k) let you roll the purchase price and the cost of the improvements into a single loan, which can be a great fit if you're buying a property with the plan to add a unit.
- Construction loans. For bigger projects, like building a new triplex or fourplex.
A few things to know first
- Talk to the city before you get too far. Lot size, setbacks, utilities, and trees can all affect what you can build, and the rules vary by city and zone.
- Get real cost estimates. Construction costs in Portland aren't cheap, so make sure the numbers work before you commit. A detached ADU can easily run into six figures.
- Know the landlord rules. If you plan to rent it out, Portland's tenant protection rules apply.
- Check on short-term rentals. If you're thinking Airbnb, check the city's rules first, and know that some fee waivers come with restrictions on how the unit can be used.
Bottom line
The rules for what you can do with a residential lot in Portland have changed more in the last few years than in the previous several decades, and right now there's a real financial incentive to build. Whether you're a homeowner looking to add a unit or an investor looking for your next project, it's worth exploring.
If you've got a property in mind, let's talk through the financing options. I'm happy to help you figure out which approach makes the most sense for your situation.
This information is general and not legal, zoning, or tax advice. Zoning, permitting, and fee waiver rules are set by each city and are subject to change; confirm requirements with the local permitting office. Financing is subject to credit, property, and program approval. Some loan products may be offered through approved lending partners.
Want this run on your actual numbers?
Everything above is a worked example. Give me your real figures and I'll tell you what it looks like for you, with no application and no credit pull.