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Short Summary
Main recommendation: Before buying, become an expert in your local ADU zoning code and verify that an accessory dwelling unit is an allowable use at the specific property, then favor an attached ADU as the cheapest, most efficient entry point. The speaker frames an attached ADU as "one step above the famous house hack," while detached units cost more but can command higher rents.
Key Points
- Confirm legality first: the speaker's biggest warning is buying a house in a zone where an ADU isn't allowed, and recommends calling and emailing the planning office, or visiting in person, to ask whether an ADU can be built, converted, or attached and what standards apply.
- Focus on single-family zones: the speaker says to look for single-family houses that can be converted into a duplex, not multifamily zones, which carry higher development standards.
- Check building standards, not just allowability: common hurdles include parking (a third off-street spot is often required, sometimes paved as an impervious surface), side and rear setbacks, building height, and HOA restrictions.
- Legal units add value: the speaker says an ADU gives two legal units with two certificates of occupancy, which can increase rents, resale value, and appraisals.
- Buy an existing ADU where appraisers undervalue them: in markets that value ADUs at about 70 cents on the dollar, the speaker suggests buying a primary house at market rate with a completed ADU as a way to acquire the second unit at a discount.
Details Worth Noting
- Concrete instructions:
- Research the local ADU code: identify the target area, find the ADU section of the municipal code (usually one to three pages, sometimes around 10 pages), and read the building standards.
- Contact the planning office directly by phone or email, or go in person, and ask whether an ADU can be built, converted, or attached at the specific property and what standards must be met.
- Build the criteria before shopping: for attached ADUs, the speaker's example is a single-family house in an R1 zone with at least 2,000 square feet, two bathrooms, at least three off-street parking spots, and a lot of at least 6,000 square feet.
- For detached ADUs, look for a flat, large backyard, known allowability, achievable side and rear setbacks, plenty of parking, and ideally alley access that could allow dividing the yards with a fence.
- For a low-cost attached conversion, look inside the existing structure, often the master bedroom and master bath: wall off one section with one walk-through door into a common hallway, add an exterior entrance, and build a patio and walkway to the parking area.
- Costs cited are from the Pacific Northwest in 2022: conversions start around $100 per square foot, and detached standalone units on a fairly flat lot within 50 to 100 feet of the primary house start around $225 per square foot.
- Some conversions have been done for less than $30,000, but system development charges (SDCs), which fund roads, parks, and city services, start around $10,000. A kitchenette plus an HVAC mini-split can bring the total to about $20,000, and electrical panel or old sewer line upgrades can add more.
- Financing options mentioned include home renovation loans, cash, private money, and 401(k) or 457(b) loans from yourself. The speaker mentions Tarl's BRRRR strategy videos as a related resource, without this being a BiggerPockets product plug per se.
Bottom Line
An ADU can be a practical, legally sound way to turn one single-family property into two units, but its value depends on local rules, parking and setback limits, construction costs, and how appraisers in your market value ADUs.
