Quick Answer: Yes, you can add a second master bedroom (also called a secondary master suite or in-law suite) to a San Jose home, and it’s one of the highest-ROI room additions for Bay Area multi-generational households. A second master suite typically includes a bedroom (12×14 feet minimum), walk-in closet (6×8 feet), and full private bathroom with shower, vanity, and toilet. Cost: $80,000-$180,000 for a 400-600 sq ft addition that connects to the main house. A ground-floor second master suite is particularly valuable for aging parents or in-law use — it avoids stair access. This is different from an ADU (which has its own entrance and kitchen) — an in-law suite is attached and accessed through the main house. Both require a building permit in San Jose. The second master suite adds approximately $150,000-$300,000 to the home’s resale value in San Jose’s $1M+ market.
Second Master Suite Addition Cost — San Jose 2025
| Scope | Cost Range | Notes |
|---|---|---|
| Bedroom + private bath (no closet) | $65,000 – $110,000 | 400 sq ft addition |
| Bedroom + walk-in closet + full bath | $90,000 – $160,000 | 500 sq ft addition — most popular |
| Full in-law suite (bedroom + sitting room + bath) | $130,000 – $200,000 | 700 sq ft addition |
| Private entrance addition (for in-law access) | +$5,000 – $15,000 | Separate exterior door from addition |
| Estimated home value increase (San Jose $1M+ home) | $150,000 – $300,000 | Based on comparable sales with in-law suites |
Quartz Construction designs and builds second master suites and in-law additions throughout San Jose. Room addition services. CSLB #1003436 | Call (650) 749-7436.
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