Gravel Delivery FAQ: What Gets Measured or Named Wrong

Stand at the job with a tape in your hand and almost every question below is answerable from what you can see: the area, the depth you want when it is finished, and what the ground under it is doing today. The questions that cause trouble are the ones where the thing in front of you and the thing on the order form use different units or different names. Those come first.

The number that goes wrong before anything is ordered

Spread three inches deep, how far does a single yard reach?

A cubic yard is 27 cubic feet, so the coverage depends entirely on the depth you spread it at: at 3 inches, about 108 square feet. That is the figure worth memorizing, because a great many bed and path jobs land near that depth and it gives you a quick sanity check on any result. For any other depth the arithmetic is 27 divided by the depth in feet, and the material calculators will run it and give you the tonnage with it.

Names and seasons that catch Maryland buyers out

CR-6, GAB, #57: what are those names telling a buyer?

Maryland aggregates are specified by MDOT SHA Section 901, and graded aggregate base, shortened to GAB, is the highway base course term. On residential work the same dense-graded material is called CR-6, and that is what it is listed as here. Crusher Run is a separate product at 3/4 inch minus, not another name for the same thing. Washed stone is ordered by number, so #57 and #8 describe a size range and a grading rather than a brand. Stone dust and screenings are the same material. These are descriptions of how material is specified locally, not a certification held by this storefront, so if your job is being inspected against a written spec, compare it with the size and grading printed on the product listing.

Which months will Maryland ground actually let me build this?

Base, driveway and paver work runs spring through late fall. The limit at both ends is compaction: frozen ground and saturated ground will not take it, whatever the calendar says. That window is shortest on the Garrett County plateau, where winters are the longest in the state and the thaw holds work up well into spring, and longest on well drained sandy loam. Planting and lawn work has a second good stretch in autumn, when the ground is still warm and the rain is more reliable. Storm season is the argument for doing drainage work before you need it rather than after.

Which jobs belong with a licensed engineer before any stone is chosen?

Retaining walls above a modest height, shoreline work on tidal water, stormwater design and anything near a sinkhole-prone limestone valley. Those need a designed answer from a licensed engineer or a ruling from your county office, not a material recommendation, and they need it before any product is chosen. The same applies within 1,000 feet of tidal waters and tidal wetlands, the band the Chesapeake and Atlantic Coastal Bays Critical Area covers. Lot coverage inside it is capped, and the cap explicitly counts areas covered with gravel, stone, shell, pavers and permeable pavement, so a parking pad in stone counts against it. There is no single statewide percentage: a Limited Development Area is held to 15 percent, Resource Conservation Areas are stricter, and the county Critical Area program administers the rules and is the authority to ask. Get the requirement in writing, then bring it back and match it against the catalogue.

Stone and soil that look alike on a screen

Fines in or fines out: which one drains and which one compacts?

The fines decide it. A base blend such as CR-6 or crusher run contains crushed stone, gravel and dust in a graded range, so the small particles fill the gaps and the layer locks up dense under a roller. That is what you want under a drive, a pad or pavers, and it is exactly what you do not want in a drain, because the dust silts it closed. Drainage wants washed, open stone with the fines taken out: #57 Stone, #67, drain rock, or #4 where the flow is heavy. If you remember nothing else, remember that a material which compacts and a material which drains are opposites, and no single product does both jobs well.

Fill dirt, screened topsoil, garden soil: can one stand in for another?

No, and substituting one for another is an expensive mistake to undo. Fill Dirt is screened earth with minimal organic matter, used to raise a grade, backfill or close a low spot, and nothing is meant to grow in it. Screened topsoil is a balanced sand, silt and clay blend for the top few inches where seed or sod goes. Garden soil is enriched with compost for raised beds and planting areas. The usual sequence on a regraded yard is fill dirt to bring the level up, then topsoil in the upper layer, then seed. They also weigh differently, about 2,400, 2,200 and 2,000 lb per cubic yard respectively, so the tonnage changes with the choice.

Ground from Garrett to Talbot, and what goes under the stone

Does Garrett County ground want different stone from Talbot County ground?

More than most buyers expect for a state this size. Thin, stony soils over shale in Garrett and Allegany counties come with a 36 inch frost depth and steep runoff, so drives need a base that drains and water carried across rather than down. In the limestone valleys around Hagerstown and Frederick, spread drive and downspout water out instead of concentrating it, since funneled runoff can open a sinkhole. Central Piedmont silt loam goes soft when saturated and needs a base thick enough to bridge it. Coastal Plain ground on the Western and Eastern Shores is unconsolidated sand, silt and clay with a high water table in low spots, so the base sits above the wet. Frost runs about 30 inches across most of the state and 24 inches in several Eastern Shore counties.

Fabric under stone, under riprap, under a base: which of those?

It depends on which layer you are laying. Under decorative stone on a bed or a path, fabric earns its place by keeping stone out of the soil and slowing weeds. Under riprap on a bank or shoreline it is part of the detail, keeping the soil from washing out between the rocks. Under a compacted base it is a judgment call, and a woven separation fabric on soft, silty subgrade can stop the base grinding down into the ground. What fabric will not do is substitute for depth or for drainage; on wet Piedmont silt it holds nothing together if the layer above is too thin. It is not a catalogue item here either, so source it from a local landscape supplier rather than adding it to this order.

Once the material and the depth are settled, choose the tonnage on the catalogue. Rounding, a bed that curves round a deck and turning a tape measure into a tonnage all sit in the calculators. The delivery day itself, and what the checkout screen settles, are on the delivery page.

Who operates Maryland Rock Supply?