95% Compaction and 4 inch Lifts: San Antonio Driveway Base Preparation
O'Leary Development GroupSeptember 2, 2026
Contractor grade driveway base preparation for San Antonio homeowners and contractors: 4 inch lifts, 95% compaction, and same day delivery.
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Build a durable driveway base by stripping organic soil, proof-rolling the subgrade, placing aggregate in 4-inch lifts, and compacting each lift to 95% Standard Proctor density (AASHTO T99). Aim for 4 to 6 inches of compacted base for residential traffic, 6 to 12 inches under heavy loads or poor soils, and grade everything at a minimum 2% slope away from structures.
TL;DR:
Building a driveway base requires compacting aggregate in 4-inch lifts to 95% of Standard Proctor density, with a total thickness of 4 to 12 inches depending on load and soil conditions.
Proper grading with at least a 2% slope away from structures is essential to manage water runoff and prevent damage, using drains or swales as needed.
Excavation should include removing all organic materials and proof-rolling the subgrade to identify and fix soft spots before laying the base.
Material choices like angular crushed stone or recycled concrete are recommended, with geotextile fabric added on clay or silty soils to improve stability.
Final readiness for paving involves verifying no soft spots, achieving proper compaction, and ensuring correct grade and drainage before surface installation.
Every solid driveway base starts on paper, not with a shovel. Walk the site first and decide your width (10 to 12 feet for a single-car path, 16 to 24 feet for a double), then choose between a crowned center or a one-way cross-slope depending on how the land already drains. Flat lots usually need a crown; sloped lots often drain better with a simple one-way pitch toward the street.
Mark the footprint with stakes and mason’s string before any equipment shows up. Set a benchmark stake for your finished elevation so every grade check afterward has a fixed reference point instead of a guess.
Before you order a single yard of material, record these numbers:
Total length and width, so you can calculate cubic yards for each layer
Existing grade elevations at the high and low ends of the driveway
Distance from the driveway edge to the foundation, septic lines, and property boundaries
Any low spots where water currently pools
Call 811 before excavation starts. It is free, and it flags buried gas, electric, and water lines so you don’t turn a weekend project into an insurance claim. If your lot has fill soil, a steep grade, or sits near a slope that could shift, get a geotechnical read before you commit to a design. It costs less than redoing a base that fails in year two.
Excavation and Subgrade Prep: Getting the Ground Ready
Your excavation depth equals the total thickness of every layer you plan to place, plus roughly 1 to 2 inches of over-excavation to account for compaction settling. For a typical 6-inch base with a 2-inch top course, that means excavating 8 to 10 inches, though soft or clay-heavy sites often need more.
Strip all organic material first: topsoil, roots, grass, and any buried debris. Organic matter decomposes over time, and a driveway built on top of it will eventually settle unevenly no matter how good the base above it is.
Once the subgrade is exposed, proof-roll it. This means driving a loaded dump truck or heavy piece of equipment slowly across the entire footprint and watching for rutting, pumping, or visible deflection. Any spot that flexes or oozes water under load is a soft spot, and it has to be dealt with before you place a single scoop of aggregate.
Steps for driveway base preparation at the subgrade stage:
Strip topsoil and organics to solid, undisturbed native soil.
Proof-roll the entire subgrade with a loaded vehicle.
Excavate and remove any soft or pumping areas.
Backfill soft spots with engineered fill or crushed stone, compacted in lifts.
Compact the native subgrade to 95% Standard Proctor density before adding base material, per UNL’s Proctor density guidance.
Install geotextile fabric over clay or silty subgrades to stop fines from migrating up into the base.
Pro Tip:If you’re renting a plate compactor for a weekend job, don’t try to skip proof-rolling because it feels like an extra step. A rented reversible plate compactor can’t fix a soft spot buried under six inches of gravel, but it can hide the problem until your driveway cracks next spring.
Homeowners can usually handle stripping and compacting a small, dry, sandy lot with rented gear. Wet clay, visible groundwater, or a driveway longer than about 40 feet is where hiring an operator with a skid steer and a real roller starts paying for itself.
How Should You Grade a Driveway to Prevent Water Damage?
Water is the single biggest enemy of any driveway base, and grading is how you beat it. Building codes call for a minimum 2% slope away from structures for at least the first 10 feet, per ICC drainage guidance, and that standard is worth following even on a driveway a code inspector will never see.
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Decide crown versus one-way slope based on your site, then hold that grade consistently through every layer of base material, not just the finished surface. A crown works well down the center of a wide, flat driveway. A one-way slope is simpler to build and often the better call on a lot that already tilts toward one side.
For water that has nowhere else to go, consider:
A French drain or perforated edge drain along the low side of the driveway
Shallow swales that redirect surface water around the pad instead of across it
Geotextile fabric separating base material from wet or clay-heavy soil beneath it
Never grade a driveway so it slopes toward your foundation. It sounds obvious until you’re staring at an uneven lot and the easy fix is the wrong one.
What Materials Should You Use for a Driveway Base?
A durable base is built in layers, and each layer does a specific job. The bottom drainage layer, often an open-graded stone like #57, lets water move through instead of pooling against your subgrade. On top of that sits the structural layer, typically crusher run or dense-graded aggregate (DGA), which locks together under compaction to spread vehicle loads across a wider footprint. FHWA’s geotechnical guidance backs this layered approach specifically because open-graded and dense-graded stone solve different problems, and neither one does the other’s job well alone.
If you’re building for pavers, add a bedding layer of coarse glass sand on top of the compacted base, screeded flat right before the pavers go down.
A few sourcing notes that save headaches later:
Recycled concrete aggregate (RCA) or crusher run works fine as structural base material on most residential jobs and is often cheaper than virgin stone.
Avoid rounded river rock in structural layers. Rounded stone won’t interlock under compaction the way angular crushed stone does, so it stays loose and shifts under load.
Non-woven geotextile fabric is worth the extra cost on any clay or silt subgrade, separating layers so fines don’t work their way up into your base over time, as Concretemetric’s subbase guide explains.
Cement or asphalt stabilization is rarely necessary for a residential driveway, but it’s worth discussing with a contractor if your subgrade is persistently wet or has a low bearing capacity.
Pro Tip:Order 10 to 15% more material than your calculated volume. Loose aggregate compacts down, and running short mid-job means a second delivery and a stalled weekend. A supplier offering road base for driveways or 3/4-inch base delivery can usually walk you through the volume math before the truck ever leaves the yard.
Placing and Compacting Each Lift Correctly
This is the step where most DIY driveways fail, not because homeowners use the wrong material, but because they place it too thick and skip proper compaction.
Spread each lift no thicker than 4 inches loose. Practitioner guidance is consistent on this: thicker lifts leave an uncompacted core underneath a compacted crust, and that core settles later, cracking whatever you built on top of it.
Check moisture before compacting. The material should feel damp, like it holds a shape when squeezed, but never dripping. Too dry and it won’t bind; too wet and the compactor just pushes it around instead of locking it down.
Choose equipment for the scale of the job. A plate compactor handles a single-car driveway fine. Anything wider than two cars, or any job with a tight timeline, calls for a vibratory roller.
Run 4 to 6 passes per lift as a starting baseline, watching for the point where the surface stops visibly deforming under the machine.
Compact every lift before adding the next one. Never bury an uncompacted layer under a fresh scoop of aggregate.
Compaction target: Residential driveway subgrades and base courses should reach 95% of Standard Proctor Density (AASHTO T99) before you move on to the next step, according to University of Nebraska research. Without a nuclear density gauge or sand cone test on hand, watch for two field signs instead: the surface stops rutting under equipment, and a probe rod meets firm, consistent resistance across the whole pad.
Moisture control matters more than most homeowners expect. A base compacted too dry will never reach target density no matter how many passes you run, and one compacted too wet just squeezes water sideways instead of locking particles together.
How Thick Should a Driveway Base Be?
Base thickness depends on what’s driving over it and what’s underneath it. There’s no single right number, but the ranges below hold up across most residential situations. These draw on figures reported by BuildCalcHub’s driveway base guidance and pavement design standards from Cement.
Standard passenger vehicles: 4 to 6 inches of compacted base is typically sufficient on decent native soil.
Heavy trucks, RVs, or frequent deliveries: Plan for 8 to 12 inches, since repeated heavy loads punch through a thin base over time.
Poor or clay-heavy subgrade: Add 2 to 4 inches beyond the standard range, or bring in imported structural fill to raise the load-bearing capacity before building up.
Low CBR soils: If proof-rolling reveals persistent soft spots even after remediation, a geotextile separation layer combined with extra base thickness usually solves it without full soil stabilization.
If you’re planning for a boat trailer, a delivery truck that visits weekly, or a future RV pad, size the base for that heaviest expected load now. Retrofitting a driveway that’s already failing costs far more than building it right the first time.
How Do You Know the Base Is Ready to Pave?
Before any surface goes down, run these checks:
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Proof-roll again. A final pass with a loaded truck should show no rutting, pumping, or visible flex anywhere across the pad.
Test compaction where it matters. A nuclear density gauge or sand cone test confirms you’ve hit 95% Standard Proctor density; if testing isn’t available, firm, uniform resistance under a probe rod is a reasonable field substitute.
Check grade with a straightedge. Lay a 10-foot straightedge across the surface; gaps larger than about ¼ inch signal a low spot that needs correcting before paving.
Watch for ponding after rain. Any standing water 24 hours after a storm means your slope isn’t doing its job yet.
Do not pave over a base showing soft spots, failed compaction checks, or ponding. Fixing any of those after the surface goes down means tearing it back out.
Finishing Notes by Surface Type
The base does most of the structural work, but the final course determines how the driveway actually performs day to day.
Gravel: Spread and screed a top course 2 to 3 inches deep using an angular stone rather than rounded pea gravel for better lock-up, though pea gravel still works well as a decorative top layer on lighter-use paths. Gravel driveways are usable almost immediately after the top course is graded.
Asphalt: A standard residential asphalt surface runs 2 to 3 inches thick, compacted with a roller while the mix is still hot. Keep vehicles off it for at least 24 to 48 hours, longer in cool weather.
Concrete: Residential slabs typically run 4 inches thick, poured with control joints spaced to manage cracking as the slab cures. Curing takes about a week before light traffic and closer to a month for full strength, all riding on how well the base beneath it was compacted.
Pavers: A 1 to 1.5 inch bedding sand layer sits directly on the compacted base, screeded flat, with edge restraints locking the perimeter pavers in place. A poorly compacted base is the single most common cause of paver driveways shifting or settling unevenly within the first couple of years.
Why We’re Qualified to Talk About Driveway Base Materials
O’Leary Development Group hauls fill dirt, road base, crusher run, and sand to construction and residential sites across Greater San Antonio every week, which means we see firsthand what base materials hold up and what customers reorder after a failed first attempt. Our online booking system lets you request a quote for road base or crushed aggregate before you finalize your excavation plan, and contractor accounts with net-30 invoicing keep larger jobs moving without payment delays. Same-day delivery means your compaction schedule doesn’t stall waiting on a truck.
When to DIY a Driveway Base and When to Call a Pro
Stripping topsoil, running a rented plate compactor, and grading a small, dry, sandy driveway are all reasonable DIY tasks for a motivated homeowner with a free weekend. Where it stops being a good DIY candidate: persistent soft spots that reappear after remediation, wet clay subgrades, or any driveway wide enough to need a vibratory roller instead of a plate compactor. Heavy equipment access and drainage design for a sloped lot are where an experienced operator earns their fee.
If you’re at the planning stage right now, take one concrete step before you do anything else: measure your driveway footprint, call 811 to check for buried lines, and request a materials quote so you know your real budget before you rent a single tool.
— BRIAN
Get Your Driveway Base Materials Delivered Same Day
Ordering the right aggregate is the one part of this process you don’t have to handle alone. O’Leary Development Group delivers road base, crusher run, sand, and gravel across Greater San Antonio with same-day service, so a compaction schedule doesn’t stall waiting on a supplier.
Once you’ve measured your driveway and decided on base thickness, ordering is simple: pick your material (most residential jobs need road base for the structural layer and 3/4-inch base or manufactured sand for bedding), enter your project address online, and get a transparent per-load quote before you commit. GPS-tracked trucks mean you know exactly when your delivery is arriving instead of guessing whether the day’s schedule is still on track. Contractor accounts with net-30 invoicing are available for larger or recurring jobs. Request a quote for dump truck hauling and material delivery and get your base materials moving toward the site today.
A layered design works best: an open-graded stone like #57 for drainage topped with a dense-graded crusher run or DGA for structural strength, compacted in 4-inch lifts to 95% Standard Proctor density.
What Should I Put Down Before a Gravel Driveway?
Strip the topsoil, proof-roll and compact the subgrade, then place a compacted structural base 4 to 6 inches thick before adding a 2 to 3 inch gravel top course.
Can I Pour Concrete Directly on Dirt?
No. Concrete needs a compacted, uniform base beneath it, typically a properly compacted aggregate subbase, or the slab will crack and settle unevenly as the native soil shifts underneath it.
How Should I Prepare My Base for Driveway Pavers?
Compact a structural base to 95% Standard Proctor density, then add a 1 to 1.5 inch bedding sand layer screeded flat, with edge restraints installed before the pavers go down.
