Turn an area and a depth into cubic yards, tons, and a delivered Bay Area cost range for Class 2 base, drain rock, pea gravel, or recycled base.
Every result is a planning estimate, not a quote or an engineering determination. Real pricing depends on soil conditions, access, existing structure, engineering requirements, and your jurisdiction’s current fee schedule. For structural questions we coordinate with a licensed engineer — we do not perform engineering ourselves. Get a site-specific estimate before committing to a budget.
Base rock is not filler. It does three jobs under a slab or driveway: it spreads wheel and structural loads over a wider patch of subgrade, it gives the crew a flat compacted platform to form and pour on, and it breaks capillary rise so ground moisture stops wicking up into concrete. Skip it or under-compact it and you get differential settlement, and the concrete above telegraphs that as cracking a season or two later.
Class 2 aggregate base is the workhorse for driveways, slabs, and flatwork because its graded fines lock together and compact to a dense, stable platform. Recycled base is crushed concrete and asphalt processed to a similar gradation; it performs well for most residential work, costs less, and keeps material out of a landfill. Drain rock is the opposite product on purpose: clean, open-graded, no fines, so water moves through it. That makes it right for French drains, under-slab drainage layers, and crawl space work, and wrong as a compacted structural base. Pea gravel is rounded and decorative, which means it never locks up under compaction and should not be used as structural base at all.
Depth follows what your plans or engineer specify, not a rule of thumb, but the pattern in the field is familiar: 4 inches is common under an interior residential slab on decent subgrade, 6 inches is typical under a driveway carrying vehicles, and 8 to 12 inches shows up where subgrade is soft, expansive, or seeing truck traffic. Compaction is where most DIY and low-bid jobs fail. Base has to go down in lifts, get moisture conditioned, and be compacted with a plate or roller. Dumping 8 inches at once and running a plate over the top compacts the top two inches and leaves the rest loose.
We spec, place, and compact base as part of every foundation, ADU slab, and flatwork pour we build, and we test compaction where the plans call for it.
Because loose aggregate compacts. The tool adds a 25 percent factor so the finished, compacted depth matches your plans instead of ending up an inch short after the plate compactor goes over it.
Recycled base is crushed concrete and asphalt graded to perform much like Class 2 at a lower delivered cost, and it is widely accepted for residential driveways and flatwork. Virgin Class 2 is still specified on some plans and for some agency work, so check what your drawings call out.
They are different products for different jobs. Drain rock is open graded so water can pass through it, which is why it belongs in French drains and drainage layers. Compacted structural base needs fines to lock up, which drain rock does not have.
Most Bay Area quarries and recyclers set a minimum load in the range of 5 to 10 tons, and short loads carry a minimum charge either way. For small patches it is often cheaper to pick up material by the yard than to pay for a delivery.
Tell us what you're building — a new home, an ADU, an addition — and we'll get back to you with next steps, usually within one business day.
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