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Drainage Is the Backbone of Every Hardscape (and Landscape) Project

  • Writer: Jonathan Garcia
    Jonathan Garcia
  • Sep 22
  • 4 min read
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When people think “patio” or “outdoor kitchen,” they usually picture pavers, colors, and patterns. We start somewhere else: drainage. If water doesn’t leave the site the way it should—above and below the surface—your investment is at risk from day one. That’s why our base system is engineered with drainage first, using 3/4" clean, open-graded stone and detailing that moves water away from structures, freeze–thaw cycles, and soils that can’t carry the load.

Below is exactly how and why we do it—supported by ICPI guidance and Unilock resources.

Why Drainage Comes First

Water is the #1 force acting on your hardscape. It saturates soil, reduces bearing capacity, expands when frozen, and transports fines that cause settlement. Industry guidance reflects this reality:

  • Minimum slopes: ICPI’s construction guidance calls for finished pavement slopes of at least ~1.5% in most cases (with roadway cross slopes of ~2%), so water sheds predictably instead of ponding. orco.com

  • Under-the-surface drainage: ICPI details the role of perforated drains, outlets, and open-graded bases to move subsurface water safely off the project. orco.com

Permeable interlocking concrete pavement (PICP) takes this further by using open-graded aggregates that temporarily store and convey stormwater before it infiltrates or exits via drains—recognized by transportation and stormwater agencies nationally. Federal Highway Administration+1

Our Base System: 3/4" Clean, Open-Graded Stone

On projects where it’s appropriate, we build the base with open-graded, no-fines aggregates—commonly ASTM No. 57 (≈ 3/4" clean)—because it performs three critical jobs at once:

  1. Rapid drainage & temporary storage (void space).

  2. Load distribution under pavers.

  3. Freeze–thaw resilience (less water retained = less heave).

ICPI technical details illustrate typical sections with No. 57 base and No. 8 bedding, showing how these layers store and route water through the system. Willow Creek Paving Stones+1

In short: our base isn’t just “rock under pavers.” It’s a drainage structure.

Surface vs. Subsurface: We Engineer Both

Surface drainage is about finished grades, cross-slope, and where water visibly flows. Subsurface drainage is about what happens after water enters joints or edges:

  • Finished grades & slope: We set stringlines and laser references so patios, walkways, landings, and drive lanes shed water at code-appropriate slopes—no flat “birdbaths.” ICPI’s tolerances and slope guidance anchor our layout. orco.com

  • Open-graded base: Our default base system uses 3/4" clean (No. 57) stone to create void space for water. Cambridge Pavers

  • Bedding layer: We use a thin No. 8 layer (or appropriate bedding per design) that won’t trap water the way dense, fine sands can. Willow Creek Paving Stones

  • Edge restraints & outlets: Where needed, we integrate perforated underdrains, daylights, or tie-ins to storm infrastructure—keeping water moving. orco.com

Why We Often Recommend Permeable Paver Systems

Permeable pavers look like traditional pavers but are designed with wider joints and open-graded bases to let water pass, reducing runoff and filtering pollutants before water reenters the ground or leaves through a managed outlet. Unilock’s technical resources highlight how these systems protect waterways and reduce strain on municipal storm sewers, while enabling beautiful, durable outdoor living spaces. Unilock+1

In many Chicagoland backyards, parkways, and pool decks, a permeable assembly is the smartest insurance policy against ponding, icy patches, and foundation stress.

Landscapes Need Drainage, Too

Plants and soils are just as vulnerable to poor drainage as pavers are. Soggy beds suffocate roots; clay soils hold water against foundations; downspouts that dump into mulch create erosion. Our landscape designs pair grading, swales, and subsurface solutions (e.g., French drains, dry wells) so hardscape and softscape work as a single water management system—not two separate projects stitched together.

Our Process on Your Project

  1. Site Walk & Water MappingWe identify collection zones (downspouts, slope breaks, low spots) and safe discharge points.

  2. Grades & TolerancesWe establish precise finish grades and cross-slopes per ICPI guidance before any excavation begins. orco.com

  3. Engineered BaseWe install open-graded No. 57 base (thickness per soil/loads/freeze depth) with a thin No. 8 bedding—built to drain. Cambridge Pavers+1

  4. Edge Restraints & OutletsWe lock the system in place and provide controlled exits for water (daylight, dry well, storm tie-in) as conditions dictate. orco.com

  5. Pavers & JointingWe select pavers (including permeable options) that suit the architecture and water strategy, supported by Unilock technical recommendations. Unilock

  6. Maintenance PlanFor permeable systems, we include simple upkeep (occasional sweeping/vacuuming of joint stone) per ICPI maintenance guidance so infiltration stays high. Unilock

The Bottom Line

  • Drainage missteps lead to settling, heaving, joint washout, efflorescence staining, icy hazards, wet basements, and plant failure.

  • Drainage-first design—with 3/4" clean, open-graded base and correct slopes—keeps your project stable and beautiful for the long run.

  • Authoritative guidance (ICPI, FHWA) and manufacturer support (Unilock) align with how we build every day. orco.com+2Federal Highway Administration+2

If you’re planning a patio, driveway, outdoor kitchen, or landscape renovation in the western Chicagoland suburbs, start where we do: with the water plan.

Sources & Further Reading

  • ICPI, Tech Spec 2: Construction of Interlocking Concrete Pavements — slopes, drainage, compaction, tolerances. orco.com

  • ICPI, Tech Spec 18 & permeable base diagrams — typical No. 57 (3/4" clean) base and No. 8 bedding for PICP. Cambridge Pavers+1

  • FHWA, Permeable Interlocking Concrete Pavement Tech Brief — overview of PICP hydrologic/structural design and maintenance. Federal Highway Administration

  • Unilock, Permeable Pavers and Advantages of Permeable Paving — benefits, water quality, stormwater relief. Unilock+1

  • Unilock, Reducing Flooding with Permeable Pavers — stormwater and resilience context. Unilock

  • ICPI/Unilock, Maintenance for PICP — routine care to keep infiltration high. Unilock



 
 
 

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