ADU vs. Home Addition: Which Is Right for You?

Comparing cost, permitting, and use cases for ADUs and traditional additions.

Published March 20, 2025

Two ways to add space

An ADU and a home addition both add usable space, but they serve different goals and follow different rules. An ADU is a separate, self-contained unit; an addition expands your main home.

The right choice depends on how you'll use the space, your lot, and zoning.

ADU: a separate living unit

An ADU is a self-contained space with its own kitchen and bathroom, often used for family, guests, or rental income. Feasibility depends on zoning, lot size, and setbacks.

ADUs require their own utility connections and permitting, and not every property qualifies.

Home addition: expanding the main house

A home addition expands your main living space — a larger kitchen, a new primary suite, or a second story. Additions require engineering, permits, and integration with the existing structure.

Additions are subject to setbacks and zoning but don't require a separate unit's utility setup.

How to choose

If you want a separate, self-contained space (for family, guests, or rental), an ADU may fit — if your property qualifies. If you want to expand your main home's living space, an addition is the answer.

We help you compare feasibility, cost, and use cases based on your property and goals.

Quick answers