Bluestone Installation & Base Preparation Guide

Why Base Preparation Matters

Bluestone itself is extremely durable—but even the best stone can fail if the base underneath shifts, traps water, or freezes. Most issues (uneven stones, cracking joints, frost heave) are caused by base problems, not the stone.

• Prevents settling and rocking
• Improves drainage and frost resistance
• Extends the life of the installation
• Creates a flatter, safer walking surface

Step 1: Planning & Layout

Before digging, define the finished size, shape, and elevation of your project.

• Mark the area with stakes and string
• Allow for stone thickness, base layers, and final grade
• Plan for a slight slope (about 1/8"–1/4" per foot) away from buildings for drainage

Tip: Dry-lay a few stones nearby to confirm spacing and joint width before committing to excavation.

Step 2: Excavation

Excavate deep enough to accommodate the full base system and the stone thickness.

• Typical depth: 8"–12" total (varies by soil and climate)
• Remove all organic material, roots, and loose soil
• Dig slightly wider than the finished area for edge restraint

In freeze/thaw climates, deeper excavation with a well-draining base is critical for long-term performance.

Step 3: Geotextile Fabric (Recommended)

Installing landscape fabric over the subgrade helps prevent soil migration into the base material.

• Separates native soil from crushed stone
• Improves base stability
• Helps reduce future settling

Step 4: Base Material Installation

The base layer provides strength and drainage. Use a high-quality crushed stone with fines.

• Material: Crusher run / modified stone / ¾" minus
• Depth: 4"–6" minimum (more for heavy traffic or poor soils)
• Install in lifts of 2"–3" and compact each layer thoroughly

Use a plate compactor for best results. A properly compacted base should feel solid and not shift underfoot.

Step 5: Bedding Layer Options

The bedding layer allows fine leveling of the stone. The best option depends on the installation method.

Stone Dust / Screenings (Dry-Set)

• Common for patios and walkways
• Easy to adjust and level
• Compact lightly before setting stone

Concrete Sand

• Improved drainage compared to stone dust
• Less prone to erosion
• Popular for flexible installations

Mortar or Concrete Bed

• Used for steps, landings, and structural applications
• Requires proper drainage and expansion joints
• Best handled by experienced installers

Step 6: Setting the Bluestone

Place stones carefully, working from one end outward.

• Set stones gently—do not drop into place
• Check level frequently
• Maintain consistent joint spacing
• Adjust bedding as needed for thickness variation

For natural variation stone, rotate pieces to distribute color evenly across the project.

Step 7: Joint Filling

Once stones are set, joints must be filled to lock everything in place.

• Polymeric sand: clean look, resists weeds and washout
• Stone dust: traditional look, may require occasional refilling
• Mortar: used for rigid installations and formal designs

Sweep joint material in gradually and compact lightly to ensure full joint depth.

Step 8: Edge Restraint & Final Compaction

Edge restraint keeps the installation from spreading over time.

• Use aluminum, plastic, or stone edging where appropriate
• Backfill edges with soil or stone for support
• Lightly compact around the perimeter

Drainage & Freeze/Thaw Considerations

Bluestone performs best when water can drain away freely.

• Avoid trapping water under the stone
• Maintain slope away from structures
• Use open-graded base materials where drainage is critical

Common Installation Mistakes to Avoid

• Insufficient base depth
• Poor compaction
• No drainage slope
• Using rounded gravel instead of crushed stone
• Ignoring thickness variation in natural stone