Quick Answer: A primary suite addition (a new bedroom plus en-suite bathroom) in San Jose, California costs $180,000-$350,000 for a typical 400-600 square foot addition. This includes: new foundation, framing (for the bedroom, bathroom, and walk-in closet), plumbing rough-in and finish (toilet, double vanity, tub/shower), electrical (dedicated circuits, recessed lighting), HVAC (ductwork extension or mini-split), insulation and drywall, flooring (typically tile in bath, hardwood or LVP in bedroom), and all finishes. The wide cost range is driven by the quality of finishes: a mid-range primary bath with quartz countertops, subway tile, and standard fixtures costs $40,000-$70,000 while a luxury primary bath with marble, heated floors, and a soaking tub can cost $80,000-$150,000. A permit is required — San Jose building permit processing for a room addition typically takes 6-10 weeks.
Primary Suite Addition Cost Breakdown — San Jose 2025
| Cost Component | Mid-Range | High-End |
|---|---|---|
| Foundation (400-600 sq ft) | $18,000 – $28,000 | $22,000 – $38,000 |
| Framing and roofing | $22,000 – $35,000 | $28,000 – $50,000 |
| Plumbing rough-in + finish | $15,000 – $25,000 | $25,000 – $50,000 |
| Electrical | $8,000 – $14,000 | $12,000 – $22,000 |
| HVAC (mini-split) | $4,000 – $7,000 | $6,000 – $12,000 |
| Insulation, drywall, texture, paint | $12,000 – $22,000 | $16,000 – $30,000 |
| Flooring (tile + hardwood/LVP) | $8,000 – $18,000 | $18,000 – $45,000 |
| Bathroom fixtures and tile | $18,000 – $35,000 | $45,000 – $100,000 |
| Permit fees and engineering | $6,000 – $12,000 | $8,000 – $15,000 |
| Total | $111,000 – $196,000 | $180,000 – $362,000 |
Quartz Construction builds primary suite additions throughout San Jose and the Bay Area. We handle everything from architectural design to final finish. CSLB #1003436 | Call (650) 749-7436.
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