Accessory Dwelling Unit construction: Costs, Codes, TimelineAccessory Dwelling Unit construction: your complete 2026 guide

Accessory Dwelling Unit construction is one of the smartest ways to add space, income, and long‑term value to your property in 2026. This clear guide covers costs, codes, timelines, and smart planning so you can build with confidence and avoid common delays. For a deeper walkthrough, see our Accessory Dwelling Unit Cost Estimate: 2026 Pricing Guide.

Because rules vary and choices can

Backyard cottage construction is one of the most practical ways to add living space, rental income, and long-term equity to a home you already own — and this guide gives you the complete roadmap from first sketch to move-in day. You will learn how to plan, budget, permit, finance, and build an efficient accessory dwelling unit (ADU), a self-contained secondary home built on the same lot as a primary residence. In addition,

Choosing the right accessory dwelling unit financing options is the single decision that determines whether your backyard cottage, garage conversion, or in-law suite gets built on schedule and on budget. Because ADU projects in California typically run from $150,000 to well over $400,000, the funding path you pick affects your monthly payment, your tax bill, and how quickly you can start construction. In this guide, you will compare every major way to pay