Gravel, Stone and Soil Delivery in San Mateo, CA

Cut, fill and pavement at the survey point

The USDA soil survey labels the map unit at the ZIP's center point Urban land-Orthents, cut and fill complex, 0 to 5 percent slopes. Each part of that long name carries meaning. Orthents are young soils with almost no layering, and the phrase cut and fill says the ground was scraped, moved and spread again during construction. What lies under one yard can be native earth, while the yard next to it may sit on hauled-in fill mixed with old brick, gravel or clay.^[1]

The survey counts 50 percent of the map unit as urban land, meaning paved or built over. Half of the mapped area is sealed under streets, roofs and slabs, and the other half is the reworked earth between them. Rain that lands on the sealed half has nowhere to soak in, so it runs toward whatever open ground is left, and a lawn edge or a planting strip can take far more water than its own share of a storm.^[1]

Reading reworked ground before you dig

Because cut and fill ground varies from spot to spot, a test hole is the best first step. Dig a narrow pit to the depth of the planned base and look at the walls. Dark, crumbly earth with roots is old topsoil that should come out before stone goes down. Gray or mottled clay holds water and will want a fabric layer. Chunks of rubble or loose sand mean the fill was never packed, and the crew should compact the floor of the hole before building on it.^[1]

Once the subgrade is firm, a woven fabric across the footprint keeps soft fill from mixing into the stone above it. Road Base spread in thin lifts and rolled hard gives a stable platform for a drive, a shed pad or a patio. Crushed Concrete makes a good substitute and compacts much the same way. Where runoff from paved neighbors crosses the site, a trench of Drain Rock along the uphill edge catches it before it reaches the base, and a short run of #57 Crushed Stone at a downspout spreads the flow so it does not cut a channel.^[1]

Rain at the airport station, and no hard freeze

The nearest NOAA normals station is San Francisco Intl AP, CA, about 4 miles from the ZIP. It averages 19.6 inches of precipitation a year. That much rain, landing on a mix of pavement and open fill, is enough to soften a poorly built base and to wash fines out of a surface that has no crown, so drainage carries more weight in a project plan than any other weather factor.^[2]

The airport station records 0 days a year with a low of 32 F or colder. Frost heave, the lifting that cracks slabs and loosens gravel in cold places, plays no part in the design. That leaves water as the main force that wears a gravel surface down, and it lets bed work, seeding and stone projects go ahead in any month that suits your schedule.^[2]

The ground at the center point stands 10 feet above sea level. On a site that low and nearly flat, there is little natural fall to carry water away, so building in a gentle slope with the base itself does the job that the land does not.^[3]

Patios, pavers and compact yards

A paver patio on reworked ground needs a firm, even bed. Lay fabric over the compacted subgrade, add Road Base in lifts and pack each one, then screed a thin layer of Concrete Sand to set the pavers in. Stone Dust Screenings can take the place of the sand in a walkway that sees light traffic, and Mason Sand swept into the joints locks the pavers together. A row of River Rock or 3/8" Crushed Stone along the edge catches drip from the eaves and keeps splash off the siding.^[1]

Small planting areas between paved surfaces do best in raised beds or deep containers filled with Garden Soil, since the native fill under them is a gamble. Blend Compost into Topsoil for a lighter mix where vegetables will grow. Brown Shredded Mulch or Wood Chips over the top hold moisture through the dry stretches and soften the impact of runoff from nearby pavement. For a side yard too narrow for a mower, Pea Gravel or Walkway Gravel over fabric gives a clean, low-care surface that lets the 19.6 inches of yearly rain soak through.^[1],[2]

Road Base or Crushed Concrete under a shed pad

A shed, a hot tub or a storage pad on reworked ground needs a base that will not settle unevenly, and two materials do most of that work. Road Base is crushed rock with the fines left in, so the larger pieces lock together and the dust fills the spaces between them. Wetted and compacted in thin lifts, it sets up into a hard, flat layer that holds a level for years. It is the safer pick where the fill underneath is soft or mixed, because its even grading spreads the load and resists punching through.^[1]

Crushed Concrete comes from broken slabs, curbs and foundations run through a crusher. It packs almost as firmly as Road Base and suits the same jobs, and the recycled source appeals to buyers who want a lighter footprint on the region's quarries. Its pieces can carry a little leftover cement dust, which helps it stiffen once it gets wet. On either material, the build is the same: test-dig the subgrade, compact it, lay fabric, add the base in lifts and pack each one until a boot heel barely marks it. Slope the finished pad slightly so the 19.6 inches of yearly rain at the airport station runs off its face instead of soaking along one edge. A border of 3/4" Crushed Stone around the pad keeps soil from creeping onto it and gives drip from the roof a place to land.^[1],[2]

Homes in ZIP 94401 and the state base standard

ZIP 94401 holds 13,818 housing units by the latest Census count. The city of San Mateo as a whole holds 42,641 units.^[4]

Only 30 percent of homes in ZIP 94401 are detached single-family houses, compared with 42 percent across San Mateo. Owner-occupied homes make up 43 percent of the occupied housing in the ZIP. Apartments and attached homes therefore make up most of the addresses here, and Gravel Valet sizes many of its loads in this ZIP for courtyards, shared walks and small patios.^[4]

The median home in ZIP 94401 was built in 1964. The citywide median is 1965, one year newer.^[4]

Caltrans, the state transportation department, sets its aggregate base standard as Class 2 Aggregate Base, Section 26-1.02B, in its Standard Specifications (2026). That rule governs the stone layer under state pavements and gives contractors a common reference point for graded, compacted base.^[5]

ZIP 94401 is in San Mateo County, and Gravel Valet also runs loads to Daly City, Hayward and Fremont.^[5]