# Gravel driveway layers: base, depth, and stone types Layer thickness, stone choice, crown, ditches, and ordering for a gravel driveway, from road agency manuals. Guide page: (published 2026-10-05, updated 2026-10-05). This Markdown version has the guide's key points, outline, FAQs and sources; the full article, with its worked examples and diagrams, is on the page. ## Key takeaways - Build in layers: a stable base, then a surface (wearing) course of crushed, well-graded stone that packs hard. - FHWA guidance: the surface course at least 4 in thick and preferably 6 in, with the gravel structure at least 12 in above natural ground. - Crown the surface about ½ in per foot of width from the center (about 4%) so water runs off instead of soaking in. - Use crushed gravel with fines, not rounded bank-run or pea gravel, for any layer that needs to lock together. - Order extra: loose loads lose roughly 25–30% of their volume once spread and compacted. ## In this guide 1. [How the layers work](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#how-the-layers-work) 2. [How thick each layer should be](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#how-thick-each-layer) 3. [Choosing stone for each layer](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#choosing-stone) 4. [Crown and cross-slope](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#crown-and-cross-slope) 5. [Ditches and drainage](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#ditches-and-drainage) 6. [How much gravel to order](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#how-much-gravel-to-order) 7. [Maintenance](https://www.howmanyyardsdoineed.com/guides/gravel-driveway-layers/#maintenance) ## Frequently asked questions ### Can I use pea gravel for a driveway surface? Rounded stone does not lock together under tires. Vermont's driveway guidance says stone that is round should not be used as packing gravel and recommends crushed gravel with packing dust instead. ### How much crown should a 12 foot wide gravel driveway have? At ½ inch per foot from the center to the edge, the center of a 12 ft driveway sits about 6 × ½ = 3 inches higher than its edges. ### Why did my gravel go further than I expected, or not far enough? Delivered gravel is loose. Idaho's gravel roads manual advises expecting a 25–30% loss in volume once it is spread and compacted, so a compacted layer needs more loose material than its finished volume. ### How often should a gravel driveway be graded? Vermont's driveway guidance recommends grading at least 2–4 times a year, in the spring and fall. Shape it when the top is damp, not dry, so the surface does not loosen and ravel. ### Why do driveway guides recommend crusher run? Vermont's driveway guidance recommends asking for quality crusher run gravel because it packs into a hard surface that resists erosion. Correct driveway gravel has packing dust plus irregular, broken edges that bind together. Ask your supplier for the gradation of the specific product. ## Related calculators and guides ### Calculators - [Gravel Calculator](https://www.howmanyyardsdoineed.com/gravel-calculator/) — Gravel, crushed rock, or landscape rock volume in cubic yards and meters, with an optional weight from your supplier's density. - [Topsoil Calculator](https://www.howmanyyardsdoineed.com/topsoil-calculator/) — Topsoil volume in cubic yards and meters for lawns, beds, and fill, with an optional weight from your supplier's density. ### Guides - [How Much Does a Cubic Yard of Gravel Weigh?](https://www.howmanyyardsdoineed.com/guides/how-much-does-a-yard-of-gravel-weigh/) — Tons per cubic yard for crushed aggregate, loose versus compacted, and how to convert a volume into an order by weight. - [What Is a Cubic Yard?](https://www.howmanyyardsdoineed.com/guides/cubic-yards-explained/) — What a cubic yard is, how to convert area × depth into yards, and how much ground one yard covers. - [How to Plan a Bulk Material Delivery](https://www.howmanyyardsdoineed.com/guides/planning-material-delivery/) — Rounding to supplier increments, questions to ask, and a checklist before bulk material arrives. - [How to Measure an Irregular Area](https://www.howmanyyardsdoineed.com/guides/measuring-irregular-areas/) — Split odd shapes into rectangles, triangles, circles, and trapezoids, then average width and depth. - [Bagged vs. Bulk Materials: Which Should You Buy?](https://www.howmanyyardsdoineed.com/guides/bagged-vs-bulk-materials/) — How to compare bags and bulk delivery using bags per cubic yard and your own local prices. ## Sources - [Unpaved Road Dust Management, Chapter 6: Construction and Additive Application](https://www.fhwa.dot.gov/clas/ctip/unpaved_roads_dust/ch_6.aspx) — Federal Highway Administration, Center for Local Aid Support. Used for: Wearing course ≥ 4 in, preferably ≥ 6 in; gravel structure ≥ 12 in above natural ground; target crown 5% ± 1%. Checked 2026-10-05. - [Crowned Driveways, Good Gravel, and Rock- or Grass-lined Drainage Ditches (Lake Wise BMP)](https://anrweb.vt.gov/PubDocs/DEC/WSMD/Lakes/Docs/LP_BMPCrownedDriveways.pdf) — Vermont Agency of Natural Resources, Lakes & Ponds Section. Used for: Crown ½ in per foot of width from the center; ¾ in top-layer stone; ditches 1.5–2 ft deep, side slopes no steeper than 2:1. Checked 2026-10-05. - [Gravel Roads Manual (2021)](https://lhtac.org/wordpress/wp-content/uploads/2021/04/Gravel-Roads-Manual-Final_Web-2021.pdf) — Local Highway Technical Assistance Council (Idaho). Used for: Crown ≈ ½ in per foot (4%), not above 6% or below 2%; loose loads lose 25–30% of volume when spread and compacted. Checked 2026-10-05. - [NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement](https://www.nist.gov/system/files/documents/2025/12/30/appc-26-HB44-20251222.pdf) — National Institute of Standards and Technology. Used for: 1 yd³ = 27 ft³; 1 US gal = 231 in³. Checked 2026-10-03. **Estimate only.** Results are planning estimates computed from the numbers you enter. They are not engineering, structural, or code advice. Confirm quantities, product yields, and installation requirements with your supplier, the product label, and your local building authority before you order or build.