Sample brokerage on Antenna's Pollinator platform. Agents and listings are fictional.View Antenna →
An agent at Antenna Realty Los Angeles · (555) 555-0100
Free tools

Make the math work with an ADU

In an expensive market, the most credible lever is an income unit. See whether a rental ADU pays for its own construction and what it does to your real monthly cost.

Buy vs. Rent True Monthly Payment Seller Net Proceeds Commercial Cap Rate ADU Unlock
05

ADU Unlock

A concept model. Move the sliders to see whether a rental ADU pencils out on the home you have in mind, and how much it lowers your real monthly cost.

Live
Real monthly cost, after rent
$7,420 / mo
ADU pays for itself
Home monthly payment$6,227
ADU build payment / mo$1,693
Net ADU rent (after vacancy)$2,112
Without the ADU$8,629
Monthly savings vs. no ADU$1,209

Assumes property tax 1.25%, insurance 0.35%, maintenance 1% of value per year on the main home. ADU build financed at the construction-loan rate over the chosen term. A concept estimate, not a quote, appraisal, or financial advice.

How to read this

When does an ADU actually pay off? Three honest tests.

An ADU is a real lever only when all three of these clear at once. Numbers shift block to block. Treat this as a starting point, then talk to an agent and a builder who know the neighborhood.

01
Pays its own way
Net rent covers the construction payment.
When rent minus vacancy clears the monthly cost of financing the build, the unit is self-sustaining.
02
Carries the home
Real monthly drops below your "no ADU" baseline.
The remainder after rent applies against your home payment. If it lowers your real monthly meaningfully, the home becomes carryable.
03
Fits the lot
The lot, zoning, and access actually allow it.
Numbers are nothing without setbacks, utilities, and a parking strategy. Walk the lot before you write the offer.
Reference

How does ADU Unlock work?

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 the real monthly cost on the main home.

What are the model 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.

What people ask most

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 the 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.

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?

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.

Want this run on a specific address?

A Collective agent can pressure-test the build cost, the rent comps, and the zoning on the home you have in mind. Free, no pressure.