When installing an interlocking paver patio, walkway, or driveway, one of the most important steps is making sure you have a solid base. The depth you need to excavate and the type of base material used will depend on the project details. In general, a compacted aggregate base like Brock paver base provides a durable, well-draining foundation for pavers. Here’s a closer look at how deep to dig and tips for getting the base depth right.
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What is Brock Paver Base?
Brock paver base is a crushed stone aggregate material that compacts firmly and drains well. It typically contains a blend of stone dust, 3/4 inch crushed stone, and smaller stone particles. Brock paver base conforms to ASTM D2940 specifications for grading and quality.
The angular crushed stone particles interlock when compacted. This creates a dense, interlocking matrix that supports the weight of the pavers and traffic above. The mixture of particle sizes also allows for excellent drainage. Water can flow through the base instead of pooling below the pavers.
Brock paver base is an ideal choice for a structural base layer beneath concrete pavers. It provides a permanent, hard surface that resists erosion or deformation from freezing and thawing. The rigid paver base transfers the load of the pavers and traffic across a wider area instead of concentrating it in small spots like soft, shifting soil would.
How Deep to Excavate for Paver Base
For patios, walkways, and most standard paver applications, a 4 to 6 inch deep layer of compacted paver base is ideal. Here are recommendations based on the project details:
Patio or Walkways
For patios and walkways:
- Excavate 4 to 6 inches deep for the base layer
- Compact and level the soil subgrade
- Add and compact 4 to 6 inches of Brock paver base
- Screed 1 inch of bedding sand over the base
- Install pavers on the screeded bedding sand
A 4 inch depth is adequate for lighter foot traffic. For larger patios or walkways with more weight, use a 6 inch thick paver base.
Driveways
For driveways and areas with vehicle traffic:
- Excavate 6 to 8 inches deep for the base
- Compact and level the subgrade
- Install a 6 to 8 inch layer of compacted paver base
- Screed 1 inch of bedding sand
- Install pavers on the bedding sand
The thicker base depth handles heavier loads from vehicles without settling or deforming. Use 8 inches for driveways with heavy vehicles or in cold climates.
Over Soft Soils
If the soil subgrade is very soft, muddy, or sandy, excavate 2 to 4 inches deeper than the recommended base thickness. For example, dig down 8 to 10 inches total and add 6 inches of Brock paver base. The extra depth compensates for potential settling of soft soils over time.
Over Firm, Stable Soil
If the native soil is hard, compacted clay or undisturbed soil with excellent load-bearing capacity, you may be able to reduce the base depth slightly to 4 inches. This depends on the paver manufacturer’s recommendations and intended traffic loads.
Installation Tips for Getting the Base Depth Right
To achieve the proper compacted base depth, here are some installation tips:
- Use stakes and layout strings as depth guides when excavating.
- Account for the thickness of the bedding sand layer (typically 1 inch).
- Use a vibratory plate compactor to compact the soil subgrade before spreading any base material.
- Dump and spread Brock base in lifts or layers no more than 4 inches thick before compacting.
- Use the vibratory plate compactor to achieve maximum density and stability.
- Check thickness frequently with a measuring rod. Add or remove material carefully to meet the required depth.
- Screed rails can help maintain consistent depth when spreading and smoothing the bedding sand.
Taking the time to prepare a solid base helps prevent future problems. The base material and depth also depend on drainage and freeze-thaw considerations. Contact a professional paver installation contractor if you need additional guidance.
Key Factors for Determining Base Depth
The depth requirement can vary between projects depending on:
Drainage Needs
Well-draining soil allows using a thinner base. Poor drainage may require a thicker base and possibly a sub-base layer of drainage aggregate.
Load Requirements
Heavier loads from vehicles, equipment, or furniture require deeper bases. Lighter foot traffic needs less depth.
Soil Conditions
Firm, undisturbed soils may allow a thinner base. Soft, loose, or unstable ground needs more depth to prevent settling.
Freeze-Thaw Cycles
In cold climates with soil movement from frost heave, make the base thicker to prevent paver damage.
Manufacturer Guidelines
Follow the recommended base depths specific to the paver product used on the project.
Typical BASE Depths for Pavers
Here is an overview of typical compacted base thicknesses for paver installations:
| Application | Compacted Base Depth |
|---|---|
| Standard patio or walkway | 4 to 6 inches |
| Driveway or parking area | 6 to 8 inches |
| Over soft subgrade soil | 6 to 10 inches |
| Over firm, undisturbed soil | 4 inches minimum |
| Cold climates | 6 inches or greater |
The subgrade soil type, drainage, traffic loads, and climate are all important considerations for proper base thickness.
SUBGRADE Preparation Tips
Proper subgrade preparation is critical for ensuring the base layer performs as intended:
- Excavate 4 to 6 inches deeper than the planned base thickness.
- Remove all topsoil, organic material, debris, and sod.
- Cut through and compact any soft spots or loose soils.
- Level and contour the subgrade for proper drainage as needed.
- Use a plate compactor to consolidate the subgrade before base installation.
- Moisten sandy or dry soils before compacting.
The time taken to prepare a stable, load-bearing subgrade prevents problems down the road. Ensure any drainage pipes, electric conduits, or edging restraints are installed before adding the base.
Base Options for Enhanced Drainage
In low-lying or wet areas, a subsurface drainage system helps prevent water from pooling under the pavers. Options include:
Drainage Aggregate Sub-base
A 4-6 inch sub-base layer of clean, washed drainage aggregate adds drainage capacity below the paver base. Drainage aggregate contains larger crushed stone particle sizes around 1 to 2 inches.
Geotextile Fabric
Installing geotextile fabric between the subgrade and drainage aggregate layers prevents soil from migrating up into the sub-base. This keeps the drainage system clear.
Perforated Pipe
Perforated PVC or corrugated drainage pipes in the sub-base provide an exit point for excess water to drain away from the pavers into storm sewers or lower elevation areas.
Edge Drainage
Use drainage swales, gravel trenches, or French drains along property lines or edges to collect surface runoff and prevent subsurface pooling under the pavers.
Material Calculations
To estimate the amount of materials needed, determine the square footage of your project. For example, to pave an area of 10×20 feet (200 sq ft):
- Excavation depth: 6 inches over 200 sq ft is 100 cu ft
- 4 inch compacted base depth needs 67 cu ft of Brock paver base
- 1 inch bedding sand needs 17 cu ft
- Add 5-10% extra for cutting, waste, and compaction loss
Use an online material calculator to estimate needs for larger projects. Having extra base material on hand is better than running short.
Costs
Material costs for a 6 inch base beneath a paver patio or walkway typically run between $2 – $4 per square foot. The labor to excavate, compact, and install the layers adds $3 – $10 per square foot depending on site factors. Complex drainage installations can increase costs.
A professional contractor with the right equipment can complete installation much faster and efficiently than a DIY project. Their experience also ensures proper base installation and compaction.
Conclusion
Installing a proper base is one of the most important steps in a successful paver project. Allowing adequate depth for compacted Brock paver base creates a long-lasting pavement structure.
Base requirements vary depending on soil and site factors. For standard paver applications, a 4 to 6 inch thick base often provides the best results. Heavier traffic, poor drainage, or weak soils call for increased base depth.
With care taken on subgrade preparation, proper drainage, and consistent base installation, interlocking pavers can provide decades of service with little maintenance required. Investing in a high quality base pays dividends over the lifetime of the pavement.