Achieving the Perfect Slope: Ensuring Drainage in Permeable Hardscapes
A well-designed permeable hardscape is only as effective as its ability to manage water. Proper slope in the base and surface layers is crucial for directing water away from foundations and preventing pooling, erosion, or structural failure. Skipping this step can compromise even the most well-intentioned installations.
Are Slope and Pitch the Same?
Yes, in construction, “slope” and “pitch” are often used interchangeably, but both refer to the intentional incline designed to manage water flow. For permeable hardscapes, this slope ensures water moves efficiently toward infiltration zones or drainage systems. Without it, water stagnates, undermining the installation and increasing the risk of long-term damage.
The Correct Calculation for a 2% Slope
Key Rules for Permeable Pavement Installation
1. Never Install Level:
- Permeable hardscapes must always slope to facilitate drainage. The excavation of the base should direct water away from structures and foundations. Higher slope percentage will be required.
2. Direct Water with Precision:
- Use a slope to guide water toward perforated pipes for collection and controlled exfiltration in the base.
- Install pipes with holes facing down in the 4 o’clock and 7 o’clock positions, ensuring efficient water capture and flow.
3. Choose the Right Pipe:
- Use solid PVC pipes to prevent crushing and ensure a straight, debris-free run.
- Avoid sumps (dips) in piping to eliminate water pooling and sediment accumulation.
Tailoring Slope to Drainage Needs
1. Full Infiltration:
- Ideal for well-draining soils.
- Combine with ROMEX TRASS BED, which maintains base stability while allowing water to infiltrate efficiently. Slope away from buildings.
2. Partial Infiltration:
- Suitable for areas with slow-draining soils, like clay-heavy regions.
- Redirect excess water using a perforated pipe system while maintaining surface permeability with ROMEX jointing materials. Slope the excavation towards the middle or all to the far side from a foundation.
3. Full Exfiltration (No Infiltration):
- For locations with non-draining subsoils or purpose-built to capture and hold rainwater for special use,
- Proper excavation and pitch ensure effective water movement to where it is required. Pond liners and storage tanks are typically used with this method.
Swales & Strip Drains
Swales are areas purposefully sloped toward each other to direct water to where they meet.
This area where two slopes meet is ideal for strip drains. Strip drains are easily made using ROMEX Profi Deko resin to bind clean aggregate. This creates a long-lasting and highly permeable zone.
Risks of Improper Slope
- Pooling: Increases freeze-thaw damage and creates hazardous slip zones.
- Erosion: Stagnant water undermines base layers, leading to instability.
- Structural Failure: Without adequate drainage, surfaces may crack, shift, or settle unevenly.
Why ROMEX Products Are Essential for Success
ROMEX TRASS BED and jointing materials are engineered to optimize water management:
- TRASS BED provides a stable, void-rich base, supporting infiltration or controlled drainage.
- ROMEX jointing materials allow for water to infiltrate through the joints and can be easily cleaned/maintained with a pressure washer to remove debris and prevent clogging of the joint. Surface maintenance is recommended on a bi-annual basis.
Together, they complement the correct slope, ensuring durable, long-lasting hardscapes.
Plan for Long-Term Success
Every project is unique, requiring customized slope planning based on site conditions, climate, and drainage objectives. Combining the right excavation techniques with ROMEX products ensures water flows efficiently, protecting your investment and enhancing durability.
Ready to start? Contact ROMEX Hardscapes for professional guidance and materials designed for worry-free installations.
