Best Drainage Rock for French Drains:
Crushed Angular Gravel (½” – 1 ½”)
A French drain is a gravel-filled trench. It redirects excess water away from your home. Moving water away helps prevent foundation damage and over-soil saturation. The key to an effective French drain is using the right drainage rock to keep water moving freely.
Best Rock for a French Drain:
- Crushed angular gravel (½” to 1 ½” size): Angular edges interlock, preventing shifting while allowing excellent drainage.
- Washed, clean stone: Avoid fine dust and debris that could clog the drain over time.
- Limestone, granite, or trap rock: The durable materials resist compaction and last for decades.
Installation Tips:
- Dig a trench 12” wide and 18-24” deep. Slope it 1 inch per 8 feet.
- Line with geotextile fabric. It helps prevent soil from getting in and clogging it up.Add a 3-4” layer of crushed angular gravel as a base.
- Place a perforated drain pipe on top, then cover with 6” of drainage rock before folding the fabric over and backfilling.
🔹 Why this rock? Crushed angular gravel stays in place while allowing water to flow through. It ensures long-term drainage efficiency.
Best Drainage Rock for Dry Wells
Large Crushed Stone (1 ½” – 3”)
Dry wells are underground pits filled with drainage rock. It collects and slowly disperses excess water into the soil. The best rock for a dry well leaves large voids. This prevents clogging and allows water to percolate efficiently.
Best Rock for a Dry Well:
- 1 ½” to 3” crushed stone: Larger rocks create voids for water storage and gradual absorption.
- Washed rock only: Sediment-free rock prevents clogging and maximizes drainage efficiency.
- Basalt, granite, or limestone: Strong, non-decomposing rocks for long-term durability.
Installation Tips:
- Select a low-lying area. Dig a hole 3-4 feet deep and at least 2 feet wide.
- Line with geotextile fabric. It helps keep the soil out of the stone.
- Fill with large crushed drainage rock (at least 1 ½” in size).
- Cover with soil and sod, or use decorative rock for an open design.
🔹 Why this rock? Larger crushed stones allow maximum water flow and prevent clogging over time.
Best Drainage Rock for Swales
River Rock (¾” – 2”)
A swale is a shallow, sloped trench. It moves water across a yard without causing erosion. The best drainage rock for a swale slows water flow while allowing infiltration.
Best Rock for a Swale:
- ¾” to 2” river rock or pea gravel: Smooth, rounded stones slow water and reduce erosion.
- Mix Sizes: Using a combination of ¾” to 2” stones. It allows for varied water absorption and stability.
- Washed rock only: Prevents soil buildup and maintains drainage efficiency.
Installation Tips:
- Dig a shallow trench 6” to 1’ deep, following the natural slope of the land.
- Use river rock as a base layer, then add larger stones to slow water movement.
- Line with geotextile fabric underneath to keep soil from mixing into the rock.
🔹 Why this rock? River rock prevents erosion while allowing controlled water drainage through the swale.
Best Drainage Rock for Around Downspouts
Pea Gravel & Crushed Rock Mix (½” – 1”)
Downspouts that release water too close to your foundation can cause serious foundation issues. The best drainage rock for this area should quickly disperse water while preventing erosion.
Best Rock for Around Downspouts:
- ½” to 1” pea gravel: Smooth, rounded stones allow water to drain without compacting.
- Crushed angular gravel (¾” size): Prevents shifting and holds the base in place.
- Limestone or granite mix: Durable materials that resist washout.
Installation Tips:
- Extend downspouts no less than 5 feet away from the foundation.
- Create a 2×2-foot gravel pad where water exits.
- Use a mix of pea gravel and crushed stone to absorb runoff efficiently.
🔹 Why this rock? Pea gravel prevents splashback, while crushed rock stabilizes the area and directs water flow.
Best Drainage Rock Around Foundations
Crushed Stone (¾” – 1 ½”)
A gravel barrier around your foundation prevents water from pooling. It also improves drainage. The right rock must allow water to pass freely while preventing soil erosion.
Best Rock for Around Foundations:
- ¾” to 1 ½” crushed stone: Medium-sized angular gravel provides excellent drainage.
- Limestone, trap rock, or granite: Durable, long-lasting materials.
- Washed stone only: Eliminates fine particles that can cause blockages.
Installation Tips:
- You will create a 12-inch-wide border around the foundation. Cover it with crushed stone.
- Slope the ground away from the foundation. The slope needs to be at least 6 inches over 10 feet.
- Use geotextile fabric beneath the gravel. It helps prevent soil from washing away.
🔹 Why this rock? Crushed stone maintains its structure, ensuring long-term foundation protection.
Foundation Drainage Rock Chart
| Drainage Application | Best Rock Type | Size | Why It Works |
| French Drain | Crushed Angular Gravel | ½” – 1 ½” | Provides stability & excellent water flow |
| Dry Well | Large Crushed Stone | 1 ½” – 3” | Prevents clogging & allows deep water infiltration |
| Swale | River Rock | ¾” – 2” | Reduces erosion & slows water flow |
| Downspouts | Pea Gravel & Crushed Rock Mix | ½” – 1” | Prevents splashback & stabilizes drainage |
| Foundation Borders | Crushed Stone | ¾” – 1 ½” | Keeps water away from the foundation & prevents erosion |
Choose the right drainage rock. This way, you ensure your home stays dry. You keep your yard stable. Your foundation remains happy and healthy.
Final Thoughts: Best Drainage Rock for a Dry Foundation
Water damage is one of the biggest threats to any home. Use the right drainage rock in the right places. You can protect your foundation. It helps prevent erosion. You keep your yard dry year-round. Use our guide and take a proactive approach to managing runoff. You’re solving immediate water issues and fortifying your home against future moisture problems. If you think you have foundation problems, contact Arch Foundation Repair for help.
Grab your shovel. Stock up on the best drainage rock. Transform your landscape into a well-drained, flood-resistant fortress!
See All In Series:
- Six Foundation Drainage Systems Options
- Best Types of Foundation Systems, Mix & Match
- Foundation Drainage Maintenance
- Foundation Water Damage Problems & Solutions
- How to Improve Clay Soil Drainage
- Foundation Drainage Material – DIY Water Control
- Foundation Drainage Installation Costs
- Foundation Drainage Material, Why and How they Work
- Best Drainage Rock to Safeguard Your House Foundation
