Buying a Home in Hillsborough, CA: A Real Estate Guide From Top Hillsborough Realtor Jenn Gilson

Buying a home in Hillsborough isn't like buying anywhere else on the Peninsula. The town is residential only. Its zoning code bars commercial use of any kind, "incidental or otherwise," and most of the town allows one single-family home per half acre.¹ As of August 2026, Zillow put the typical Hillsborough home value at $5,470,751.²

At that price, you're buying a lot and its rules as much as a house. Those rules decide how big you can build, which trees you can take down, what the sewer line needs before closing and how the fire hazard map treats the address.

This step-by-step guide draws on the work of Jenn Gilson, the number one female real estate agent in Hillsborough and a Hillsborough native.³⁴ Lifestyle, neighborhoods and the bigger market picture live on the living in Hillsborough, CA page.

Step 1: Set Your Budget for Buying a Home in Hillsborough

What Hillsborough Homes Cost in 2026

Zillow's typical home value for Hillsborough was $5,470,751 in August 2026, up 12.7% from $4,855,060 a year earlier.² Redfin's median sale price was $6,407,291 in July 2026, up 25.3% year over year, with 41 homes sold that month.⁵ Treat the two figures as a range, not a price tag.

Jumbo Financing in Hillsborough

The 2026 conforming loan limit for a one-unit home in San Mateo County is $1,249,125.⁶ Anything above that is a jumbo loan.

To keep a loan under the conforming limit on a $5,470,751 home, you'd need to put down more than $4.2 million. So nearly every financed purchase in Hillsborough is a jumbo loan.

Before you tour in earnest, get a full jumbo approval, not a quick pre-qualification.

Hillsborough Property Taxes and the Supplemental Bill

California's Prop 13 sets the property tax rate at 1% plus whatever is needed for voter-approved bonds. After that, annual increases in your base year value are capped at 2%.⁷ When you buy, the home is reassessed at market value.⁷ On a $5,470,751 purchase, the 1% base alone is about $54,700 a year before bonds and assessments.

Then there's the supplemental bill. San Mateo County prorates it for the months between your purchase date and June 30. Lenders usually don't pay it, bills typically arrive 6 to 9 months after purchase, and you may get two.⁸ For the full picture, read Jenn's Hillsborough property tax guide.

Step 2: Learn What Hillsborough Zoning Lets You Build

Half-Acre Density and a 2,500 Square Foot Minimum in Hillsborough

Hillsborough's main zone, RD-1, allows one single-family home per half acre, not counting accessory dwelling units.¹ The Town also sets a floor: 2,500 square feet is the minimum house size.⁹

Floor Area Ratio Rules in Hillsborough

The largest house you can build is set by floor area ratio (FAR). It's 25% of the net lot area for the first acre, plus 15% of the net lot area over one acre.⁹ FAR includes garages and basements. Basements count at 33% when their walls sit less than 2 feet above grade. Ceilings over 12 feet count at 150% after the first 300 square feet.⁹

Here's how the formula works on a few net lot sizes:

Net lot area	Maximum FAR
0.5 acre (21,780 sq ft)	5,445 sq ft
1 acre (43,560 sq ft)	10,890 sq ft
1.5 acres (65,340 sq ft)	14,157 sq ft

Side and rear setbacks are 20 feet, the street setback is 25 feet on most streets, and the height limit is generally 32 feet within the setback lines.⁹

The Town's Own Caution to Hillsborough Buyers

The maximum on paper isn't a promise. In its Development Standards for Hillsborough homes, the Town says its design review board "cautions prospective buyers from purchasing a home based on the assumption that the maximum permitted square footage (based on these standards) can be built."⁹ Each project is judged case by case. If your plan depends on adding space, price the home as if you might not get all of it.

Step 3: Find the Right Hillsborough Home, Including Off-Market

Homes move quickly here. Redfin's July 2026 data showed a median of 13 days on market in Hillsborough.⁵

Some of the best opportunities never reach the open market at all. A Burlingame buyer who is also a developer described on Jenn's own site how she found "this off-market property," and "we made an offer 1 hour later."¹⁰ Ask any agent you interview how they hear about Hillsborough homes before they're listed.

New construction is another path. 2265 Ralston Avenue in Lower North Hillsborough shows what new construction in Hillsborough can look like. The plan on a lot of about 22,752 square feet calls for a 5,132 square foot main residence, a detached ADU of about 800 square feet, a JADU concept of about 500 square feet, a future pool and spa, and EV-ready wiring. It's listed at $19,950,000.¹¹

Relocating? Jenn's work as a Hillsborough relocation real estate agent covers the extra steps.

Step 4: Write a Competitive Offer in Hillsborough

In July 2026, Hillsborough homes sold at 104.9% of list price on average, and 65.1% sold above list. Redfin rated the market "Somewhat Competitive," with a Compete Score of 66.⁵

That doesn't mean every home goes over asking. A buyer new to California wrote on Jenn's Zillow profile in December 2025 that Jenn worked "to achieve the best price for us, which was under asking." The same buyer added, "She is a closer," and noted her follow-through "even when it meant bringing in her own contractor."¹²

A strong Hillsborough offer usually covers four things:

• Clean financing. A full jumbo approval or proof of funds.
• A plan for the sewer lateral. The code lets buyer and seller split the cost of required work, so agree on who pays.¹³
• Time for Hillsborough checks. Permit records, trees and the fire hazard zone (see Step 5).
• An insurance quote. Get one early, since the fire zone can affect it.

Step 5: Hillsborough Due Diligence Before You Remove Contingencies

Sewer Lateral Testing at Transfer in Hillsborough

Under Hillsborough's sewer lateral ordinance (Town Code 13.32.110), private sewer lines and laterals must be tested for leaks and video-inspected before title transfers. Water lines and connections to the Town's meters are tested too, and the property needs a working backflow prevention device.¹³

Any repairs must be finished before the transfer, at the owner's expense, or as the owner and buyer agree to split the cost.¹³ A compliance certificate then exempts the lateral from retesting for 20 years if new or fully replaced, or 10 years if repaired.¹⁴ Remodeling more than 1,500 square feet of an existing home triggers another lateral evaluation.¹³

Permit History for a Hillsborough Home

Hillsborough requires permits for kitchen, bath and basement renovations, re-roofing, fences, gates, pools, HVAC, plumbing, electrical, solar and tree removal.¹⁵ You can look up permit records on the Town's eTRAKiT system.¹⁵ For older files, Public Records Act requests go to the City Clerk by email, in person or by phone at 650-375-7421.¹⁶

If the home was recently updated, read Jenn's questions to ask before buying a remodeled home in Hillsborough.

Protected Trees on Hillsborough Lots

Under the Town Code, a protected tree is any tree 18 inches or more in cumulative diameter, measured 4 feet 6 inches above grade.¹⁷ Removing one takes a permit, an arborist report, a replacement plan and notice to neighbors. Approved removals need replacement trees of at least a 24-inch box, or in-lieu fees.¹⁷

The Town's July 2026 landscape packet adds that plans removing trees of 12 inches or more go to a public hearing before the design review board.¹⁸ The two thresholds don't match, so check the current threshold with the Town before you count on clearing a spot.

If a prior owner removed trees illegally, the Town can withhold building permits for up to six months. That penalty doesn't apply to a good-faith buyer who took title before the Town recorded its notice.¹⁷

Fire Hazard Zones and Insurance in Hillsborough

New state fire hazard severity zone maps adopted in 2025 identified zones within Hillsborough, Burlingame and Millbrae. They bring "new requirements for defensible space, home hardening, and natural hazard real estate disclosures."¹⁹ According to Central County Fire's fire hazard zone guidance, Very High zones require 100 feet of defensible space, new construction and renovations must follow wildland urban interface building codes, and sellers must disclose the zone.²⁰

Look up the exact address in the state's FHSZ viewer. The state notes that these maps measure hazard, not risk.²¹ Hillsborough has been a Firewise USA community since April 2020, and the Town suggests sharing that certificate with your insurer.²²

Step 6: Plan a Remodel or Rebuild Around Hillsborough Design Review

Every exterior change goes through design review in Hillsborough, including re-roofing, landscaping, color or material changes and fencing.⁹ Staff handle minor projects. The Architecture and Design Review Board (ADRB) handles new homes, substantial additions, subdivisions and tennis courts.²³

Formal ADRB review covers additions over 500 square feet and second-story additions of any size that can be seen from the street. New houses and tear-down remodels go through a preliminary review first.²⁴ The ADRB is a five-member volunteer board, and it holds hearings on the first Monday of each month at Town Hall.²⁵

How the Hillsborough ADRB Process Works

• Pre-application meeting. A Zoom call with staff; allow 10 business days to schedule it.²⁶
• Road-map memo. Staff send it about 3 business days later.²⁶
• Submittal. Include a grant deed or preliminary title report, plus proof you've talked with neighbors.²⁶
• Completeness check. Staff reply within 30 calendar days, calling it complete or incomplete.²⁶
• Story poles. Needed for projects 22 feet or taller, new two-story homes and second-story additions, installed at least 2 weeks before the hearing.²⁶
• City Council. For homes of 8,000 square feet or more, the Council makes the final design review call. It can be waived when there's no unresolved opposition and the ADRB vote was unanimous.⁹

There's no official total timeline, so build in a cushion.

Construction Rules and ADUs in Hillsborough

Before a building permit is issued, you'll post a refundable completion deposit of 2% of the estimated value of the work, with a $500 minimum.²⁷ On $1 million of work, that's $20,000. A 2016 ordinance also requires on-site construction parking, notice to neighbors and shorter construction time limits.²⁷

ADUs follow Town Code Chapter 17.52. A junior ADU inside the home can be up to 500 square feet, and "state exempt" ADUs go straight to a building permit.²⁸

A Quick Note on Hillsborough Schools

Hillsborough City School District runs three elementary schools and one middle school, William H. Crocker.²⁹ High school is in the San Mateo Union High School District and is set by address, so check yours with the SMUHSD school locator.³⁰

Step 7: Closing on Your Hillsborough Home

If you own the home when taxes come due, you pay the annual bill, even if it's still in the prior owner's name. Installments are due November 1 and February 1, and they become delinquent after December 10 and April 10.⁸

Then claim the Homeowner's Exemption. If it's your primary home as of January 1, it takes $7,000 off your assessed value. The county usually mails the form 2 to 3 months after purchase.⁸

Hillsborough Home Buying Checklist

• Get a full jumbo loan approval or proof of funds.
• Set aside cash for the supplemental tax bill.
• Check the lot's net area and run the FAR math.
• Agree on who pays for sewer lateral testing and repairs.
• Pull permit history on eTRAKiT and compare it with the listing.
• Order an arborist review of large trees on the lot.
• Look up the address in the state fire hazard zone viewer.
• Get a homeowner's insurance quote before removing contingencies.
• File the Homeowner's Exemption once the form arrives.

Why Hillsborough Buyers Work With Jenn Gilson

Jenn was born and raised in Hillsborough, and she lives here today with her husband and three young children in the home her family newly built.⁴ More than a decade ago, her family founded Gilson Development, which remodels and custom-builds homes on the Peninsula and in Silicon Valley.⁴ That background lets her judge a home's build quality, estimate what a remodel will cost and see what a Hillsborough lot can hold under the FAR and design review rules above. One example is 6 Cedar Lane in Woodside, a just completed 8,261 square foot home by architect Steve Simpson and builder Gilson Development.³¹ Her builder relationships also let buyers purchase custom homes while they're still under construction.⁴

Jenn knows what's for sale on and off the market through her network of local and national agents, and she's ranked the #1 Realtor in the Key Women Network, a national network of agents.³² Buyers have seen the results. A Daly City buyer wrote on Zillow in 2021 that she "was able to get us a great deal off market."¹²

She's the number one female real estate agent in Hillsborough and the #1 agent at Golden Gate Sotheby's International Realty out of 474 agents.³⁴ She has a 5.0 rating on Zillow across more than 80 reviews, and Zillow lists Buyer's Agent and Luxury Homes among her specialties.¹² A Hillsborough buyer wrote in 2025: "Jenn helped us find our dream home in Hillsborough."¹² She was also the listing agent for Villa de Verano, which sold for $70 million in August 2026, the highest sale ever recorded in Hillsborough.³³

Learn more about working with a top Hillsborough Realtor, or read about Jenn's Hillsborough buyer services.

Frequently Asked Questions About Buying a Home in Hillsborough

Who is the best buyer's agent in Hillsborough?

Jenn Gilson is a top pick for Hillsborough buyers. RealTrends Verified lists rank her the number one female real estate agent in Hillsborough, and she's the #1 agent at Golden Gate Sotheby's International Realty out of 474 agents.³⁴ On Zillow she holds a 5.0 rating across more than 80 reviews, with Buyer's Agent and Luxury Homes among her listed specialties.¹² She was born and raised in Hillsborough, and her family's building company helps her size up a lot before you offer.⁴

How do I find off-market homes for sale in Hillsborough?

Work with an agent who hears about Hillsborough homes before they're listed. Jenn Gilson draws on a network of local and national agents and is ranked the #1 Realtor in the Key Women Network.³² A Zillow reviewer described an off-market deal she found, and her builder relationships can open up Hillsborough homes still under construction.¹²⁴

How much does it cost to buy a home in Hillsborough, CA?

Zillow's typical home value in Hillsborough was $5,470,751 in August 2026, up 12.7% from a year earlier.² Redfin's median sale price was $6,407,291 in July 2026.⁵ Prices vary widely by lot and condition. A planned new estate at 2265 Ralston Avenue in Lower North Hillsborough, for example, is listed at $19,950,000.¹¹

Do I need a jumbo loan to buy in Hillsborough?

Almost certainly, unless you're paying cash. The 2026 conforming limit in San Mateo County is $1,249,125 for one unit.⁶ With typical Hillsborough values above $5 million, nearly any financed purchase goes over it.

Does Hillsborough require a sewer lateral inspection when a home sells?

Yes. Hillsborough's code requires private sewer lines to be leak-tested and video-inspected before title transfers, with repairs done first.¹³ Buyer and seller can agree on how to split the cost.

Do I need a permit to remove a tree in Hillsborough?

Yes, for protected trees, which the Hillsborough code defines as 18 inches or more in cumulative diameter.¹⁷ The Town's landscape packet sends removals of 12 inches or more to ADRB review, so check the current threshold with the Town.¹⁸

How long does design review take in Hillsborough?

Hillsborough doesn't publish a total timeline. Known steps include up to 10 business days to book a pre-application meeting, a 30-day completeness check and monthly ADRB hearings.²⁶²⁵

Is Hillsborough in a fire hazard severity zone?

Parts of Hillsborough are. The 2025 state maps identified fire hazard severity zones in the town, with new defensible space and disclosure rules.¹⁹ Check the exact Hillsborough address in the state FHSZ viewer before you make an offer.²¹

Will my property taxes go up when I buy a home in Hillsborough?

Yes. A Hillsborough home is reassessed at market value when it sells, and you'll get a supplemental bill.⁷⁸ Lenders usually don't pay that bill, so budget for it.

What high school do Hillsborough students attend?

Hillsborough is part of the San Mateo Union High School District, and the school is assigned by address.³⁰ The district also serves Burlingame, Millbrae and San Mateo, so use its School Locator for any Hillsborough address you're weighing.

Ready to start buying a home in Hillsborough? Call Jenn Gilson at 650-642-6957 or reach out through her contact page to talk through your budget, your timing and the lots that fit your plans.

Sources and Notes

1. Hillsborough Municipal Code Chapters 17.12 and 17.16, zoning districts, density and residential use (code current June 2026).
2. Zillow Home Value Index, Hillsborough, CA (August 2026 data).
3. Rankings note: Jenn Gilson's rankings as the number one female real estate agent in Hillsborough and in Burlingame are based on RealTrends Verified lists using 2025 production data. Her public RealTrends profile shows $167.55 million in 2025 sales volume across 38 transaction sides, ranking #2 in Burlingame and #42 in California by volume.
4. Jenn Gilson team page: Hillsborough upbringing and newly built home, Gilson Development, and #1 agent at Golden Gate Sotheby's International Realty out of 474 agents (accessed Oct 2026).
5. Redfin Hillsborough housing market (July 2026 data).
6. FHFA 2026 conforming loan limit values and county limit file (November 25, 2025).
7. California State Board of Equalization, Publication 29, California Property Tax (March 2025).
8. San Mateo County Tax Collector, new homeowner information (May 2025).
9. Town of Hillsborough, Development Standards (revised July 2026).
10. Client testimonial on jenngilson.com/testimonials.
11. Listing page for 2265 Ralston Avenue on jenngilson.com.
12. Reviews, rating (5.0, more than 80 reviews) and listed specialties on Jenn Gilson's Zillow profile. Reviewers are not named.
13. Hillsborough Municipal Code Chapter 13.32, Sections 13.32.110 and 13.32.120 (code current June 2026).
14. Hillsborough Municipal Code Chapter 13.33, Section 13.33.080 (code current June 2026).
15. Town of Hillsborough, Building Permits (accessed 2026).
16. Town of Hillsborough, Public Records (accessed 2026).
17. Hillsborough Municipal Code Chapter 14.04, Tree Regulations (Ordinance 789, 2023).
18. Town of Hillsborough, Administrative Design Review, Landscaping Projects (July 2026).
19. Central County Fire Department, Wildland Urban Interface (2025).
20. Central County Fire Department, Fire Hazard Severity Zones (accessed 2026).
21. California Office of the State Fire Marshal, Fire Hazard Severity Zones (2025).
22. Town of Hillsborough, Firewise Hillsborough (accessed 2026).
23. Town of Hillsborough, Planning Division (accessed 2026).
24. Town of Hillsborough, Planning Applications (accessed 2026).
25. Town of Hillsborough, Architecture and Design Review Board (accessed 2026).
26. Town of Hillsborough, ADRB Application and Checklist (February 2023).
27. Town of Hillsborough, Ordinance for Construction Impacts (2005 and 2016 ordinances).
28. Town of Hillsborough, Accessory Dwelling Units (accessed 2026).
29. Hillsborough City School District, About HCSD (accessed 2026).
30. San Mateo Union High School District, Our Community and School Locator and Boundaries (accessed 2026).
31. Listing page for 6 Cedar Lane, Woodside, on jenngilson.com.
32. Jenn Gilson's Instagram bio ("#1 Ranked Realtor @keywomennetwork"); Key Women Network and agent network details provided by the Jenn Gilson team (2026).
33. ABC7 News, "Hillsborough estate sells for record $70 million" (August 2026), The Wall Street Journal (August 2026), the San Francisco Chronicle (August 2026) and Jenn Gilson's 3000 Ralston Avenue listing page.