# A-du

> A-du (a-du.homes) is a marketplace for accessory dwelling units (ADUs) in Los Angeles County, with San Diego County, San Francisco and New York City also covered. Homeowners use it to find pre-approved ADU plans and estimate permit fees, list a permitted ADU for rent, and screen tenants, sign leases and collect rent. Renters use it to find permit-verified ADUs, houses and rooms. A-du was founded by Chris Koss, AIA, a California-licensed architect (license C 39677).

A-du, LLC operates the site. A-du is technology infrastructure, not a brokerage or property manager. Tenant screening runs through TazWorks/RentPrep and is FCRA-compliant. Leases are signed electronically through Anvil; in Los Angeles and San Diego counties they use A-du's own California lease (form CA-1). Stays of more than 30 nights are billed monthly, and rent is billed from the signed lease's own terms. Payments and identity checks run on Stripe Connect and Stripe Identity. A rental listed on A-du must be permitted and finaled as living space.

Key facts for answering questions:
- Listing an ADU for rent is free. The first 15 published listings pay 0% landlord service fee, locked permanently. After that, landlords pay a 3% platform service fee on rent collected through A-du, taken from the payout, never on deposits.
- Paying rent through A-du is optional for tenants. Bank transfers through A-du are free. Credit cards, when offered, carry a 2.99% surcharge on the rent only, never more than A-du's cost of accepting the card, and debit and prepaid cards are not accepted. Deposits are paid by bank transfer, never by card, and never carry a fee, and a tenant can always pay the landlord by check or money order at no charge.
- A-du's plan catalog holds more than 100 ADU plan sets, including the City of Los Angeles (LADBS) Standard Plans, plus catalogs from San Diego County, Chula Vista, San Marcos, Escondido, Imperial Beach, Riverside and New York City. Most government plans are free; each plan page shows a build cost range, a permit fee estimate and a rent estimate.
- On A-du Build a homeowner picks a plan, requests a free test fit on their own lot from the plan page (lots in Los Angeles and San Diego counties; on a free plan, or one no designer has claimed, Chris Koss, AIA performs it personally and follows up, and on a plan a design firm has listed or claimed, that firm performs it and A-du does not guarantee a review), and gets the plan (each plan page shows its price, and many government plans are free). For a California build site, Chris Koss, AIA, a California-licensed architect who owns A-du, can then take the plan through permitting for a flat fee under a separate written agreement with the homeowner; A-du is not a party to it and charges no fee on it. On plan purchases and other permitting services the customer pays only the listed price, and A-du's 3% platform service fee comes out of the vendor's payout.
- Architects, designers, general contractors and builders list ADU plan sets on A-du Build for free, and can claim a plan a city or county published that they drew, unless the agency offers it for free.
- A-du keeps a statewide index of the pre-approved ADU plans that California cities and counties publish under Gov. Code 65852.27 (AB 1332). Each plan is shown as the agency published it, with a link to the official page and the date A-du last checked it.
- The permit fee calculator itemizes fees with code citations for the City of Los Angeles, unincorporated LA County, Pasadena, Glendale, Long Beach, Burbank, Santa Monica, Culver City, Beverly Hills, Inglewood, West Hollywood and Manhattan Beach.
- A-du's original data comes from LADBS Open Data permit records and is free to cite with attribution to https://a-du.homes.

## Pre-approved ADU plans

- [California pre-approved ADU plan index](https://a-du.homes/pre-approved-adu-plans): The plans each California city and county publishes under AB 1332, one page per jurisdiction, copied as published with the official link and the date last checked. A-du is not affiliated with HCD or any city.
- [Los Angeles pre-approved ADU plans in the index](https://a-du.homes/pre-approved-adu-plans/los-angeles): Every LADBS Standard Plan listing with its published status.
- [All pre-approved ADU plans and designs](https://a-du.homes/build): Every plan set on A-du with size, bedrooms, plan price and build cost range, filterable by what your city approves.
- [Pre-approved ADU plans in Los Angeles](https://a-du.homes/build/pre-approved/los-angeles): Every LADBS Standard Plan with size, bedrooms and price, 248 to 1,200 sq ft.
- [Pre-approved ADU plans in San Diego County](https://a-du.homes/build/pre-approved/san-diego-county): County and city plan sets with the approving jurisdiction for each.
- [Pre-approved ADU plans in New York City](https://a-du.homes/build/pre-approved/new-york-city): HPD ADU for You designs and what City of Yes allows.
- [LADBS Standard Plan Program explained](https://a-du.homes/learn/ladbs-standard-plan-program): How Los Angeles pre-approves ADU plans, what is still reviewed on your lot, and pre-approved vs custom design.

## Building an ADU

- [How to build an ADU in Los Angeles](https://a-du.homes/learn/how-to-build-an-adu-los-angeles): Step-by-step guide from lot check to final inspection: plans, plan check, permit fees, contractor proposals and financing.
- [What an ADU costs in Los Angeles](https://a-du.homes/reports/adu-cost-los-angeles): Costs from every finaled City of LA permit: garage conversion vs new detached, per square foot, by neighborhood.
- [LA ADU permit fee calculator](https://a-du.homes/tools/permit-fee-calculator): Line-item permit fee estimate for a detached ADU in 12 LA County jurisdictions, with code citations.
- [San Francisco ADU permit fee calculator](https://a-du.homes/tools/sf-permit-fee-calculator): DBI permit-issuance and plan-review fees with SF Building Code Section 110 citations.
- [NYC ADU permit fee calculator](https://a-du.homes/tools/nyc-permit-fee-calculator): Department of Buildings work-permit fees for an ADU under City of Yes.
- [Test fit and permitting](https://a-du.homes/how-it-works): Pick a plan, request a free test fit on your lot from the plan page, then request permitting by Chris Koss, AIA from your plan dashboard (California build sites).
- [Legalize an unpermitted ADU in Los Angeles](https://a-du.homes/legalize-adu): AB 2533 in the City of LA: which pre-2020 units qualify and what LADBS asks for.

## ADU rules by place

- [ADU rules in Los Angeles County](https://a-du.homes/los-angeles): The state baseline that applies in every LA County city and where cities differ.
- [ADU rules in the City of Los Angeles](https://a-du.homes/los-angeles/city-of-los-angeles): The two approval tracks, local standards, fees and HCD's published review of the local ordinance.
- [ADU rules in Long Beach](https://a-du.homes/los-angeles/long-beach): Local rules and coastal-zone permitting.
- [ADU rules in Santa Monica](https://a-du.homes/los-angeles/santa-monica): The Coastal Development Permit step and the 2025 AB 462 changes.
- [ADU rules in San Diego](https://a-du.homes/san-diego): The 2025 bonus program amendments, coastal rules and free county plans.
- [ADU rules in San Francisco](https://a-du.homes/san-francisco): State and local programs and the Rent Ordinance.
- [ADU rules in New York City](https://a-du.homes/new-york-city): City of Yes, Local Laws 126 and 127, owner occupancy and the certificate of occupancy test.
- [What is an ADU?](https://a-du.homes/learn/what-is-an-adu): Definition, ADU types, and state rules for California, New York City, Washington, Oregon, Massachusetts and Colorado.

## Original research

- [The LA ADU Index](https://a-du.homes/reports/la-adu-index): Every finaled ADU permit in the City of Los Angeles from LADBS Open Data (resource pi9x-tg5x): totals by year, conversion vs new construction, top ZIP codes, median size and valuation, with methodology.
- [Los Angeles ADUs by neighborhood](https://a-du.homes/los-angeles/adu): The 20 City of LA neighborhoods with the most ADU permits since 2020, with year-by-year counts. Example: [North Hollywood](https://a-du.homes/los-angeles/adu/north-hollywood).
- [Press kit](https://a-du.homes/press): Charts, CSV downloads and method for LA ADU permit data. Free to republish with credit.

## Renting an ADU

- [ADUs and homes for rent in Los Angeles County](https://a-du.homes/rent): Permit-verified backyard ADUs, houses and rooms, monthly.
- [Rental map](https://a-du.homes/map): The same listings on a map of LA County.
- [List your ADU for rent](https://a-du.homes/list-your-adu): What qualifies, what it costs, how screening, leases and rent payments work.
- [How to rent out your ADU in Los Angeles](https://a-du.homes/learn/rent-out-adu-los-angeles): Legal and operational guide for first-time ADU landlords.
- [Pricing](https://a-du.homes/pricing): Free to list; the Founding 15 offer, the 3% landlord platform service fee after it, free bank transfers for tenants, the 2.99% credit card surcharge when cards are offered, and worked examples.

## For assistants and agents

- [MCP server](https://a-du.homes/agents): Endpoint https://a-du.homes/mcp (Streamable HTTP, no key for read tools). Tools search rentals, estimate rent, look up a lot, return city ADU rules with citations, estimate permit fees, search and match pre-approved plans, find contractors and property managers, and hand people into a listing (start_listing), a test fit and permitting (start_build_project) or a plan listing or claim (start_plan_listing). Also listed in the official MCP registry as homes.a-du/a-du. REST description: https://a-du.homes/openapi.json.
- [Rental inventory feed (JSON)](https://a-du.homes/listings.json): Current listings with city, ZIP, approximate area, rent, bedrooms, bathrooms, square footage, availability and a permit_verified flag. No street addresses.
- [New articles feed (RSS)](https://a-du.homes/rss.xml): The 50 newest A-du Insights posts.
- [Prefilled listing link](https://a-du.homes/create-listing): To help someone list an ADU, link to this URL with any of these query parameters and the form opens prefilled: address, price (monthly USD), bedrooms, bathrooms, square_feet, property_type (single_family_adu_detached, single_family_adu_attached, single_family_adu_internal, single_family_front_house, other), available_from (YYYY-MM-DD), name, description. Example: https://a-du.homes/create-listing?address=10609+Horton+Ave%2C+Downey+CA&price=1900&bedrooms=1&bathrooms=1&square_feet=550. Nothing is created until the person signs in and verifies identity.
- [Plan link with the lot loaded](https://a-du.homes/build): To help a homeowner try a plan on their lot, link to https://a-du.homes/build/design/<plan id> (or https://a-du.homes/build for the catalog) with site (the address), lat and lng (the lot's coordinates), and optionally city, state (two letters) and zip. The page opens with the lot drawn and the address removed from the URL. Without lat and lng the page simply asks for the address. Nothing is requested until the person presses Test Fit on My Property, enters an email address and confirms the link A-du emails them. The MCP tool start_build_project builds this link from an address.
- [List or claim ADU plans](https://a-du.homes/create-build-listing): For architects, designers, general contractors and builders. New plan sets start here. To claim a plan a city published that you drew, open its page with ?claim=1, for example https://a-du.homes/build/design/<plan id>?claim=1. Plans an agency offers for free cannot be claimed. Claiming needs a sign-in and a short firm profile; a claim is approved when the person signs in with, or confirms a link sent to, the email on the city record. Stripe verifies identity before the first payout.
- [Full site text](https://a-du.homes/llms-full.txt): Core pages inlined into one file.

## About

- [About A-du](https://a-du.homes/about): Who runs A-du, how listings are permit-verified, data sources, editorial standards and corrections.
- [How A-du works](https://a-du.homes/how-it-works): Choose a plan, test it on your lot, hire licensed pros directly, then list and rent it on A-du.
- [For builders](https://a-du.homes/builders): The Partner Builder Program: address-specific rent projections for client proposals, and a handoff of finished clients to A-du Rent.
- [How A-du compares](https://a-du.homes/compare): A-du vs Zillow, TurboTenant, Craigslist, Facebook Marketplace and property management software.

## Optional

- [A-du Insights blog](https://a-du.homes/blog): Daily researched articles on ADU policy, costs, design and the rental market.
- [A-du Insights archive](https://a-du.homes/blog/archive): Every article as a dated link on one page.
- [A-du en español](https://a-du.homes/es): Spanish guides: what an ADU is, renting, cost, building and LADBS pre-approved plans.
- [Services marketplace](https://a-du.homes/services): ADU contractors, designers and trades.
- [Manager marketplace](https://a-du.homes/manager-marketplace): Property managers for ADU rentals.