Gravel, Rock and Decomposed Granite Delivery in Thousand Oaks, CA

Clay That Moves With the Seasons

At the center point of ZIP 91360 the USDA soil survey maps Cropley clay, 2 to 9 percent slopes, warm MAAT, MLRA 19. The Cropley series makes up 90 percent of that map unit, so the yard is almost all clay, with little else mixed in.^[1]

Shrink-swell for this clay is rated very high, at 10 percent. Clay like that swells when the winter rains soak it and pulls apart into deep cracks by late summer. A patio, walk or retaining wall set right on top of it rises and drops a little each year, and the movement shows up as cracked concrete and tilted pavers.^[1]

The survey lists the ground as well drained and in hydrologic group C, with slow infiltration. Water runs off the slope rather than soaking in quickly, which means a downspout that empties onto bare clay can flood a low corner during a winter storm even though the soil itself is not waterlogged.^[1]

Hardscape on clay this active holds up best with a stone layer under it and good drainage around it. Put a layer of crushed stone between the clay and the finished surface, keep roof water away from the slab edges, and avoid watering patterns that soak one side of a patio while the other stays dry.^[1]

By the USGS elevation reading, the ground at the ZIP's center point lies 770 feet above sea level.^[2]

A Patio Base for Expansive Clay

Dig the patio area down several inches below the finished height and remove the loose top layer of clay. Lay a woven geotextile on the cut surface. The fabric keeps clay from pumping up into the base when it gets wet and keeps the stone from sinking into it.^[1]

Build the base from Road Base or Crushed Concrete in thin lifts, compacting each lift with a plate compactor. A thicker base than you would use on sandy ground spreads the load and smooths out the small rise and fall of the clay below. Slope it gently away from the house so rain leaves the patio.^[1]

Finish with an inch of Concrete Sand and pavers, or with Decomposed Granite packed in thin layers. Pavers forgive clay movement better than a poured slab, since each unit can shift slightly without cracking, and Decomposed Granite can be raked and rolled back into shape.^[1]

Dry Months at the Camarillo Station

The NOAA normals station closest to the ZIP is Camarillo AP, CA, about 12 miles away, and it averages 12.0 inches of precipitation a year. Most of that falls in a few winter storms, and the rest of the year is dry.^[3]

Long dry spells are when expansive clay shrinks the most. A deep layer of mulch or stone over the soil slows that drying, and a drip line that waters evenly keeps the clay from swinging between soaked and cracked near a foundation or a wall.^[1],[3]

Frost is close to absent at Camarillo AP, where a low of 32 F or colder shows up on 1 day in a typical year. Freeze damage to a base is not a concern, and tender plants rarely need cover.^[3]

Plan the hardscape for the few hard rains rather than the dry months. A gravel drive or patio that sheds water well in a January storm will stay sound the rest of the year.^[3]

Winter storms on a slope of group C clay can carry soil off a bare bank in a single night. Cover open banks with Brown Shredded Mulch on gentle grades and with River Rock or Riprap where the water gathers and speeds up, so the clay stays where it is and the storm water reaches the street clear instead of muddy.^[1],[3]

Low-Water Beds on Clay

Clay holds nutrients well but packs hard and drains slowly through its pores. Planting holes dug straight into Cropley clay can act like a bowl that fills with water in winter. Loosen a wide area instead of one deep hole, and mix in Compost or Garden Soil to open up the texture.^[1]

Raised beds filled with Topsoil and Compost let you grow vegetables or flowers without fighting the clay at all. A few inches of Brown Shredded Mulch on top holds moisture through the dry months and adds organic matter as it breaks down.^[1],[3]

For low-water gardens, River Rock and 3/4" Crushed Stone make good ground cover between drought-tolerant shrubs. Lay landscape fabric first, and leave planting pockets filled with Garden Soil so roots have loose ground to start in.^[3]

Homes and Hillside Driveways

The Census counts 15,613 housing units in ZIP 91360, and 71 percent are detached single-family houses. Thousand Oaks as a whole counts 48,084 housing units, with 66 percent detached.^[4]

The median home in the ZIP was built in 1973, against a median year of 1978 for the city. Owners live in 70 percent of the ZIP's occupied homes.^[4]

A gravel drive or parking pad on sloping clay ground needs fabric, a compacted base and a crowned top so storm water runs off to the sides. Driveway Gravel or #57 Crushed Stone over Road Base gives a firm surface, and a stone-lined swale along the uphill edge catches runoff before it crosses the drive.^[1]

Where a drive climbs the slope, keep the grade gentle at the bottom so tires do not spin the top stone loose, and use #57 Crushed Stone, whose angular pieces bite better than round gravel on an incline. A few steel stakes along the edge timbers stop the border from creeping downhill as the clay swells and shrinks under it.^[1]

Caltrans lists Class 2 Aggregate Base, Section 26-1.02B, Standard Specifications (2026) as the aggregate base for state highway work.^[5]

Decomposed Granite or Stone Dust Screenings for a Path

Decomposed Granite is the classic path material in dry California yards. It packs into a warm tan surface that fits a native garden, and when it is laid in thin, wetted layers over a stone base it stays firm. On swelling clay, that stone base matters more than the surface.^[1],[3]

Stone Dust Screenings pack even tighter and smoother, and their gray color suits a modern yard. They hold up well under a wheelbarrow or a garden cart. Each material needs a solid edge, and each will crack less than concrete when the clay below moves.^[1]

Under either path surface, a couple of inches of compacted Road Base over fabric is what keeps the clay from showing through as soft spots after the first wet winter. Without it, Decomposed Granite mixes with clay and turns into a sticky mud that clings to shoes and tracks indoors.^[1]