Hillsborough jumbo loans and 2026 loan limits.

Hillsborough was incorporated in 1910. It runs from El Camino Real, at the Burlingame and San Mateo lines, west up the hills to Interstate 280 and Skyline Boulevard, with Crystal Springs Reservoir beyond. Ralston Avenue, Crystal Springs Road and Black Mountain Road are among the roads that climb through it. The Burlingame Country Club is in the lower part of town, and the Carolands chateau stands on a hill near the middle.

The town’s zoning is its defining feature. Lots must be at least half an acre, houses must meet a minimum size, and there are no commercial districts, no apartment buildings and no condominiums. Streets wind with the hills and follow no grid. Homes include mansions from the early 1900s on the lower streets, ranch and split-level houses from the 1950s and 1960s across the middle hills, and large recent houses throughout.

The lot’s slope, the appraisal, and how a large loan’s income and assets are shown.

Much of the town is steep. An appraiser separates the usable part of a lot from the hillside and notes retaining walls, drainage and any sign of slope movement. Where the report raises a concern, a lender can ask for a soils or structural engineer’s letter. Ask the town what geotechnical review it requires for new building on a slope, which is useful to know before buying with a remodel in mind.

Houses differ widely in age and size, so appraisers often have to adjust heavily between sales. On larger jumbo loans, two appraisals are routine.

Jumbo lenders also look at what is left after closing. They commonly want to see reserves, meaning months of housing costs held in savings or investments, and they document large deposits. Vested company shares can count as assets at a discount, and retirement accounts at a further one. Parts of the town are fire hazard zones on the state’s map, so check the address there.

Lower Hillsborough is the common name for the eastern, more level part of town, nearest El Camino Real and the downtowns of Burlingame and San Mateo. It includes the streets around the Burlingame Country Club and those off Ralston Avenue, Eucalyptus Avenue and Forest View Avenue, shaded by very large old trees.

This part of Hillsborough was built up early, as country estates around the time the town was incorporated, and later divided into smaller lots that still meet the half-acre rule. Homes include grand older houses, some of them carriage houses or wings of former estates, and newer houses built to a similar scale. Level ground removes most hillside questions. What a lender looks at is age and uniqueness: a house a century old may need its wiring, plumbing or foundation checked before an insurer will write a policy, and an appraiser has to find sales of like character. Expect a second appraisal on a large loan. Creeks run through some lots toward the bay, so look up the flood map. A legal guest house counts toward value and leaves the home one unit.

Carolands is the neighborhood around the Carolands chateau, a very large French-style house built in the 1910s on a hilltop in the middle of Hillsborough. The estate’s grounds were subdivided in the years just after the Second World War, and streets such as Remillard Drive, where the chateau stands, now cross what were its gardens and woods. The chateau itself still stands and is owned by a foundation.

The homes are mostly ranch and split-level houses from the 1950s and 1960s on hilly lots of half an acre and more, together with larger houses that have replaced some of them. Many look east over the bay. Lots slope, sometimes sharply, so the usable yard can be much smaller than the lot size suggests, and an appraiser will say so. Mid-century houses on hillsides can also show their age in drainage, retaining walls and settling, which an inspection should cover. Views carry value that needs support from sales with similar views. If you intend to rebuild, the town’s limits on floor area and its design review apply, and the building work needs a construction loan.

The Tobin Clark Estate is in the southern part of Hillsborough, on high ground east of Crystal Springs Road, toward the San Mateo line and Highway 92. It takes its name from the estate that once covered these hills, whose manor house, designed by the architect David Adler for Celia Tobin Clark, remains. The land around the house was developed in the 1970s, making this one of the newer parts of town.

Homes here are large houses built from the 1970s onward, newer than most in Hillsborough, on sizable hillside lots, some with views toward the bay. Being newer, they raise fewer questions about wiring and plumbing than the older houses downhill. The points for a loan are the hillside and the edge of open land. Lots are steep in places, and graded pads, retaining walls and drainage are noted in an appraisal. The slopes here are wooded, so check the address on the state’s fire hazard map and ask for an insurance quote early. Where a street has an owners’ association, a lender counts its dues with the housing cost. Large individual houses mean few close sales and a slower appraisal.