Affordability, by design

The ADU Affordability Unlock

In a market this expensive, the most credible lever isn't a cheaper house, it's an income unit. Buy a well-built fixer with real potential, add an ADU whose rent covers its own construction debt, and a home you couldn't otherwise carry becomes carryable. Move the sliders.

Your scenario

Does the ADU pay for itself?

+$336 / mo
Self-funding
Fixer + Reno + ADU$7,605/mo
Total project cost$1,460,000
Loan amount$1,160,000
Mortgage P&I$7,524
Property tax + ins + maint$2,121
Less: ADU net rent−$2,040
Fixer + ADU (net)$7,605
Buy turnkey (no ADU)$8,225
Keep renting$4,230

Concept estimates only, not an appraisal, quote, or financial advice. Assumes a renovation/construction-to-perm loan financing reno + ADU on as-completed value, property tax ~1.25%, insurance + maintenance ~$600/mo, ADU vacancy/management 15%, ADU financed at the project's loan-to-value. Historic-overlay (HPOZ) neighborhoods can raise ADU cost and timeline.

Curious if this works for a real address?

Send me a listing and I'll run the design and the numbers: structure, potential, ADU feasibility, and the all-in math.

Reference

How ADU Unlock works

The model compares two monthly numbers: the cost of carrying the main home alone, versus the cost of carrying the main home plus an ADU minus the net rent that ADU generates. When net rent (rent minus vacancy and upkeep) covers the construction-loan payment, the ADU pays for itself. Anything beyond that lowers your real monthly cost on the main home.

Assumptions

Property tax 1.25%, insurance 0.35%, and maintenance 1% of value per year on the main home. ADU build cost is financed at the chosen construction-loan rate over the chosen term (typically 30 years for stabilized financing). Concept estimates only; permits, timeline, lot fit, and zoning are not modeled.

Common questions

What does "ADU pays for itself" mean?

Net ADU rent (rent minus a vacancy and upkeep allowance, typically 12%) is greater than or equal to the construction-loan payment for the build. At that point the unit is self-sustaining and any additional rent reduces your main-home monthly cost.

What does it cost to build an ADU in Los Angeles in 2026?

A 600-to-900-square-foot ADU typically runs $180K to $300K all-in, depending on site conditions, finishes, and whether it's a conversion, attached addition, or detached build. Premium designs and difficult sites run higher.

What rent does an ADU pull on the Westside?

A well-built one-bedroom ADU on the Westside typically rents in the $2,200 to $3,400/month range; coastal pockets and design-led builds reach $3,800+. Inland pockets land closer to $1,800 to $2,400.

What about permits and time?

Not modeled here. LA ADU timelines run 12 to 18 months from concept to occupancy, with the permitting and design phase typically 4 to 6 of those months. Plan for the carry cost during the build window.

Why a 30-year term on the build loan?

The model uses stabilized long-term financing (cash-out refi or HELOC at amortized terms) as a planning baseline. Short-term construction loans typically refinance into 30-year financing once the ADU is complete and producing rent.