Hillsborough is one of the wealthiest, most architecturally protected residential communities on the Peninsula — and its building review process reflects that. Anyone planning a remodel, addition, or new construction in Hillsborough should understand the process before they design, because the design review here meaningfully shapes what's possible.
What's different about Hillsborough
Hillsborough has no commercial development. Every property is single-family residential, most on lots over 0.5 acres. The town's building department exists primarily to protect the architectural character and the natural setting. That means:
- Design Review applies to most exterior changes
- Heritage Tree Ordinance is strictly enforced
- Front and side setbacks are large and not flexible
- Floor Area Ratio (FAR) limits total enclosed square footage relative to lot size
- Height limits are tightly enforced (typically 25–30 ft depending on zone)
The Hillsborough permit timeline
Interior-only remodel (no exterior changes)
- Plan check: 4–8 weeks
- Permit issuance: 1–2 weeks after final approval
- Typical fees: $3,000–$8,000
The fastest path through Hillsborough's process is an interior-only kitchen, bathroom, or whole-home remodel that doesn't change any exterior elevation.
Exterior changes, additions, or new construction
Design Review is required. The process:
- Pre-application meeting (1–2 weeks to schedule)
- Preliminary design review (concept-level) — 4–8 weeks
- Architectural Design Review Board hearing — 6–12 weeks after submittal
- Building plan check (after ADRB approval) — 6–10 weeks
- Permit issuance — 1–2 weeks
Total timeline: 5–9 months from initial submittal to permit in hand.
What the Design Review Board cares about
- Architectural compatibility with neighborhood character
- Massing and bulk (no boxy or "out of scale" volumes)
- Roof line and pitch
- Material choices (stone, stucco, wood — synthetic siding is heavily scrutinized)
- Window proportions and style
- Driveway placement and landscape impact
- Tree preservation and replanting
The board is genuinely design-focused. Projects that respect the existing character pass faster.
The Hillsborough Heritage Tree Ordinance
Heritage trees in Hillsborough are protected at trunk diameters of 12" or more (varies by species). Removing or significantly altering one without a permit triggers fines of $5,000+ per tree. Most projects involve a tree report before submittal — budget $1,500–$4,000 for an arborist.
Floor Area Ratio (FAR)
Hillsborough enforces FAR strictly. Maximum allowed enclosed floor area is a function of lot size and zone. For most properties, the FAR is 0.35–0.50, meaning a 1-acre lot caps at 15,000–22,000 sq ft of total enclosed area. Many remodels involve FAR analysis to confirm the proposed addition is allowed.
Typical Hillsborough project costs
Construction pricing in Hillsborough runs higher than the surrounding cities because of the design level expected. Plan for:
- Kitchen remodels: $200,000–$500,000
- Primary bath remodels: $100,000–$280,000
- Single-story additions: $1,000–$1,400 per sq ft
- Two-story additions: $1,200–$1,800 per sq ft
- New construction: $1,200–$2,500+ per sq ft
Considering a Hillsborough project? Visit our Hillsborough page or request a confidential consultation — we work with architects familiar with Hillsborough's Design Review process.
Planning a Bay Area remodel?
High Touch Consulting & Development is a licensed general contractor serving the San Francisco Peninsula and Silicon Valley. We provide free on-site consultations and fixed-scope written proposals.
