ADU Construction in Lafayette, CA

Quartz Construction designs and builds ADUs (Accessory Dwelling Units) in Lafayette, CA. Whether you want a detached backyard ADU, an attached addition, or a garage conversion, we handle design, permitting, and construction. Licensed CSLB #1003436 | BBB A+ | 4.9⭐ (65+ Reviews)

ADU Cost in Lafayette, CA

ADU construction in Lafayette costs $155,000–$290,000 depending on type, size, and finishes. Garage conversions are least expensive ($60,000–$120,000). Detached ADUs (400–1,200 sq ft) run $120,000–$280,000. Junior ADUs (JADU, ≤500 sq ft within existing home) run $40,000–$90,000. Quartz Construction provides free ADU feasibility assessments and detailed estimates.

ADU Types We Build in Lafayette

• Detached ADU — Freestanding backyard cottage (400–1,200 sq ft)
• Attached ADU — Added to side or rear of your existing home
• Garage Conversion ADU — Convert attached or detached garage to living space
• Junior ADU (JADU) — Up to 500 sq ft within existing home, with separate entrance
• Two-Story ADU — Maximizes sq ft on a small lot footprint

Why Build an ADU in Lafayette?

• Rental income: ADUs in Lafayette rent for $2,000–$4,500/month — covering your mortgage payment
• Multigenerational living: House aging parents or adult children on your property
• Home office: Private, separate studio or office space
• Home value: ADUs add $150,000–$400,000 to Bay Area home values

Free ADU Assessment in Lafayette

Call Quartz Construction at (650) 749-7436 for a free ADU site assessment in Lafayette. We’ll review your lot, zoning rules, and setbacks, and give you a clear path to ADU approval. CSLB #1003436 | BBB A+ | Serving Lafayette and all Bay Area cities.