Backyard ADU Lot Setback, Max Footprint & Rental Cash-Flow ROI Calculator
Verify whether a 16×24, 20×30, or 24×36 detached ADU fits your rear yard setback rules and calculate projected monthly rental cash flow, Net Operating Income (NOI), Cap Rate %, and Cash-on-Cash return.
Compare IRC R304-compliant backyard ADU floor plans with consolidated wet-wall plumbing cores.
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
How to Use This Tool & Frequently Asked Questions
Tips for customizing dimensions, exporting vector .SVG files, and estimating build costs
What are the standard side and rear yard setbacks for a detached backyard ADU?
In ADU-friendly states and municipalities (including California, Oregon, Washington, Texas cities, and many updated zoning codes), side and rear setbacks for detached ADUs have been reduced to 4 feet or 5 feet, with a typical 10-foot separation required from the primary dwelling.
What is a good Cap Rate and Cash-on-Cash return for a backyard ADU?
Because you already own the underlying land, detached backyard ADUs routinely achieve unlevered Cap Rates between 8.5% and 14.5%—far outperforming retail single-family rental purchases—while adding substantial appraised equity to the primary residence.
What is the most cost-effective ADU footprint size to build?
A 20' × 30' (600 sq ft, 1-Bed / 1-Bath) or 24' × 32' (768 sq ft, 2-Bed / 1-Bath) rectangular footprint with a single consolidated wet-wall plumbing core delivers the lowest cost per square foot and frequently qualifies for municipal impact-fee exemptions under 750 sq ft.