Casita ROI is approximately 100% in neighborhoods where existing homes cost $400-$500 per square foot as of May 2025. A 1,000-square-foot addition at $200 per square foot roughly doubles the property value of the added square footage. Loft conversions in older homes offer even better returns due to existing vertical space. Beyond monetary returns, casitas add functionality like office space, guest suites, or gyms that enhance daily living, making them valuable investments even beyond pure equity gains.