Paver Patio Base Preparation: Excavation, Gravel & Sand

Pavers don't sink because the stones are weak. They sink because the ground underneath them was never prepared. A paver that sits flush for five years then drops half an inch did not fail, its base did. The pavers are just the skin. What holds them up, the compacted gravel, the leveled sand, the buried edge restraint, is invisible after the job is done and forgotten by the next spring when the low spots show up. This guide is about that invisible layer. > **Get your material estimate first:** Use our [free paver base calculator](/paver-base-calculator/), enter area and traffic type to get base gravel and bedding sand totals in cubic yards and tons in seconds. --- ## The Base Is the Patio Every paver failure traces back to the base. Three forces are always working against a paver surface: water, frost, and load. A proper base resists all three. Water is the first enemy. A patio that drains poorly collects water under the pavers, softens the soil beneath the gravel, and creates a slurry that lets the whole surface sink. The gravel base gives water a path out. Frost is the second. In freezing climates, wet soil expands as it freezes and lifts the pavers unevenly. The base has to sit below the frost line or the surface will heave. Load is the third. A driveway carries the weight of a car, roughly 3,000 to 4,000 pounds concentrated on four small contact patches. Without enough compacted stone under it, the weight pushes the pavers down and forward. Build the base wrong and you will redo the patio in three to five years. Build it right and the pavers will outlast the house. ## Base Depth by Application The depth of the base depends entirely on what will drive or walk over it. More load means more stone. | Application | Gravel Base Depth | Bedding Sand | Total Excavation | |------|:--:|:--:|:--:| | **Patio / walkway** | 4 inches | 1 inch | 5 inches (plus paver thickness) | | **Driveway (cars)** | 6 inches | 1 inch | 7 inches (plus paver thickness) | | **Heavy driveway / RV** | 8 inches | 1 inch | 9 inches (plus paver thickness) | The total excavation is the base plus sand plus the paver thickness, usually 2 to 3 inches for standard pavers. A car driveway at 6 inches of base, 1 inch of sand, and 2.5-inch pavers needs a 9.5-inch hole. Measure from the finished surface you want, not from the existing ground. The [paver base calculator](/paver-base-calculator/) applies these depths automatically. Enter the area and pick pedestrian or vehicle, and it returns base gravel and sand in cubic yards plus an approximate tonnage. ## Two Layers: Gravel Base, Then Bedding Sand A correct paver base is never a single material. It is two layers with two different jobs. The **gravel base** is the structural layer. It spreads the load from the pavers across the soil below, so no single point sinks. It also drains, moving water sideways and down so it cannot pool under the surface. The **bedding sand** is the leveling layer. It sits on top of the compacted gravel and gives you a fine, adjustable surface to bed each paver into. One inch is the standard, enough to fine-tune level without being so deep that the pavers shift. The order matters and it does not reverse. Gravel on the bottom, sand on top. Sand alone as a base is a common mistake that fails within a year, sand erodes and washes out from under the pavers. ### Material Specs | Layer | Material | What to Buy | What to Avoid | |------|------|------|------| | **Base** | 3/4-inch crushed stone with fines (crusher run) | Angular, mixed-size stone that locks under compaction | Round pea gravel (rolls, never compacts), clean stone without fines (no binding) | | **Bedding** | Coarse washed concrete sand | Sharp, gritty sand that drains freely | Play sand (too fine), mason sand (too much clay) | Crusher run matters. The "fines" are the fine dust and small particles mixed with the 3/4-inch stone. They fill the gaps between stones and bind the whole layer into a near-solid pad when compacted. Clean stone without fines stays loose, like marbles, and a paver patio built on it will creep. ## Excavation: How Deep to Dig Most first-timers dig too shallow. The instinct is to remove just enough dirt to fit the pavers, but the finished surface has to end up at the right height and the base has to reach below the trouble zone. 1. **Mark the finished height.** Set stakes and string lines at the exact finished grade. Remember the drainage slope, about 1/4 inch of fall per foot, built into this height. 2. **Excavate to full depth.** Dig out base depth plus sand depth plus paver thickness, all the way across, and slightly wider than the patio by 6 to 12 inches for the edge restraint. 3. **Get to firm soil.** The bottom of the excavation, called the subgrade, must be undisturbed soil, not loose fill or topsoil. Topsoil is full of organic matter that compresses and rots; it must come out. 4. **Compact the subgrade.** Run a plate compactor over the exposed soil before adding any gravel. Loose subgrade means a soft foundation under your base. For a 300-square-foot patio with a 4-inch base, you are excavating about 2.7 cubic yards of soil before you add anything back. ## Compaction: Lifts, Not Dumps Compaction is the step that separates a patio that lasts from one that sinks, and it is the step most people rush. A plate compactor is not optional. A hand tamper cannot generate the force needed to lock crusher run together, and it cannot reach the bottom of a deep lift. Rent a plate compactor for about $60 to $80 a day. The rule is 2-inch lifts. Add 2 inches of gravel, compact it, add the next 2 inches, compact again. Dumping all 4 to 6 inches in one pile and compacting once only firms the top 2 inches. The bottom stays loose, and that loose bottom is exactly where the pavers sink into later. The base is done when a heel pressed hard into it leaves no mark. The surface should feel nearly as firm as concrete. Do **not** compact the bedding sand. The sand goes down loose and gets screeded smooth with a straight board pulled across level rails. The pavers are bedded into the loose sand, then a final pass of the compactor over the pavers vibrates them into the sand and locks the whole surface together. ## Edge Restraint and Drainage Slope Two details at the edges decide whether the pavers stay put. **Edge restraint.** Pavers under load want to spread outward. Without a solid edge, the outside row walks sideways, the joints open up, and sand leaks out. Plastic or aluminum paver edging, spiked down through the compacted base with 10 to 12-inch galvanized spikes, holds the perimeter. For a driveway, use a concrete haunch instead, a triangular wedge of concrete poured against the outer edge. It resists far more lateral force than spiked edging. **Drainage slope.** Every paver surface must slope away from the house and any structure. The standard is 1/4 inch per foot, a 2 percent grade, for patios and walkways. That slope is built into the base, not added later with extra sand. Dig the subgrade with the slope already in it so the gravel layer stays a uniform thickness. A 20-foot-deep patio drops 5 inches from the house edge to the outer edge. ## Step by Step: Building the Base 1. **Excavate and grade.** Dig to full depth with the drainage slope built in, then compact the exposed subgrade. 2. **Add gravel in 2-inch lifts.** Spread, level, compact, repeat, until the base reaches 4 to 6 inches depending on traffic. Check level constantly with a 4-foot level. 3. **Screed the sand.** Spread 1 inch of coarse sand and screed it smooth over leveled rails. Do not compact it. 4. **Set the edge restraint.** Install paver edging and spike it through the base, not just into the soil. 5. **Lay and compact the pavers.** Bed each paver into the sand, then run the plate compactor over the surface, ideally with a rubber mat or carpet scrap under the plate to protect the faces. 6. **Sweep and activate the joints.** Sweep polymeric sand into the joints, compact once more, and mist with water to harden it. The joints lock the pavers together so they cannot shift independently. ## What It Costs The materials for a paver base are the cheap part of the project, which is why skimping here is so shortsighted. | Item | Unit | Cost | 300 sq ft Patio | Line Total | |------|------|:--:|:--:|:--:| | Base gravel (crusher run) | per ton | $25-40 | 5.2 tons (3.7 cu yd) | $130-208 | | Bedding sand (coarse) | per ton | $25-45 | 1.3 tons (0.9 cu yd) | $33-59 | | Paver edging | per 8 ft | $6-10 | 4 sections | $24-40 | | Spikes | per 10 | $5-8 | 2 packs | $10-16 | | Polymeric sand | per 50 lb bag | $25-35 | 2 bags | $50-70 | | **Total base materials** | | | | **$247-393** | The full patio, pavers included, runs $8 to $15 per square foot for materials and $15 to $30 installed. The base materials are under $400 of that. Spending an extra $50 on better gravel and an extra hour on compaction is the cheapest insurance in the whole project. ## 5 Paver Base Mistakes ### 1. Skipping the Gravel Base Entirely The classic shortcut is pavers on sand on dirt. It looks fine for one season. Then a rainstorm saturates the sand, it washes into the soil, and the pavers settle into the low spots. There is no structural layer to spread the load, so every step and every tire pushes the surface down a little more. The fix is the same work you skipped, plus hauling the old pavers out of the mud. ### 2. Compacting Too Deep in One Pass A 6-inch lift of gravel compacted once firms only the top. The bottom two to three inches stay loose, and the patio sinks into them over the first year. The 2-inch lift rule is not a suggestion. It is the difference between a base that is solid top to bottom and one that looks solid on top and is hollow underneath. ### 3. Using the Wrong Sand Fine sand and play sand do not drain. They hold water, which freezes and heaves in cold climates, and they wash out through the joints in any climate. Mason sand carries too much clay and turns to a paste when wet. Only coarse, washed concrete sand works. Gritty between your fingers is the test. ### 4. No Edge Restraint Without edging, the outside row of pavers migrates outward under load and temperature swings. The joints open up, the sand spills out, and the whole field loosens. It happens fastest on driveways and curved edges. Edge restraint is not a trim detail. It is part of the structure. ### 5. Ignoring the Drainage Slope A patio built dead flat, or worse, sloped toward the house, sends water under the pavers and toward the foundation. The surface holds puddles, the base stays saturated, and frost or soft soil does the rest. Build the 1/4-inch-per-foot slope into the excavation from the start, falling away from the house. Retrofitting slope after the base is compacted means tearing it out. --- Ready to prep your paver base? Use our [free paver base calculator](/paver-base-calculator/) to get base gravel and bedding sand totals for your exact area and traffic type. Need gravel for the surrounding beds or a path? The [gravel calculator](/gravel-calculator/) handles any dimensions in tons and cubic yards. Converting between units? The [cubic yard calculator](/cubic-yard-calculator/) does the volume math for any material. For the driveway leading up to your paver patio, see our [gravel driveway guide](/blog/2026-08-07-gravel-driveway-guide/), and if the patio is cut into a slope, the [retaining wall guide](/blog/2026-08-11-retaining-wall-guide/) covers the wall that holds the hillside back.