What to Put Under Artificial Grass for Drainage in Melbourne

A lush green lawn without mud, mess, or mowing sounds like a dream until drainage becomes a nightmare. 

In Melbourne’s shifting weather patterns, the underlay beneath synthetic turf isn’t just filler; it’s the backbone of effective drainage, long-term lawn health, and household satisfaction.

Artificial turf has taken off in suburbs across Victoria, driven by time-poor homeowners, rising water costs, and the growing desire for low-maintenance outdoor spaces.

Melbourne’s climate, while famously unpredictable, presents unique drainage challenges that natural lawns often struggle to manage. That’s where synthetic solutions shine, but only if laid on the right foundation.

Choosing the right sub-base can make or break the performance of artificial grass. Poor choices lead to pooling, odour build-up, or worse, premature replacement.

In this article, you’ll discover exactly what should be laid beneath artificial grass to ensure proper drainage, specifically in Melbourne homes, what materials to avoid, and how expert planning makes all the difference for a clean, green result.

Think of synthetic grass as a system rather than just a surface. Beneath the soft, realistic blades lies a multi-layered foundation designed to manage water, maximise longevity, and support daily use without the pitfalls of natural turf.

For Melbourne homes, where the weather can swing from drought to downpour in a day, this substructure is a must!

At the core of every high-performing synthetic lawn sits a carefully chosen base layer. This sub-base acts as a drainage blanket, allowing water to pass through the grass and escape into the ground below or a designated run-off channel.

Without it, even the most advanced turf becomes a soggy, stagnant patch.

Artificial Grass Sub-Base: Is Sharp Sand Right and How Much Do You Need?

Key Components of an Effective Base

For optimal drainage, the most recommended material is crushed rock or aggregate. Crushed rock, typically between 10–20mm in diameter, provides both stability and void space for water to travel freely.

Tightly compacted yet porous, this layer mimics natural soil structure but resists compaction over time. A finer topping, such as crusher dust or decomposed granite, often follows to create a smooth, level surface just beneath the turf.

A geo-fabric or weed barrier may also be placed beneath the rock to prevent soil contamination and organic weed growth. This additional layer helps maintain a weed-free and stable structure over time while still allowing water flow.

Types of Sub-Base Materials

• Crushed Rock (Class 2 or 3): Ideal for high-traffic or heavy-use areas. Provides excellent stability and water drainage.
• Crusher Dust/Granite Sand: Commonly used as a levelling layer. Offers a firm but slightly softer finish.
• Road Base: Budget-friendly but can compact too tightly, limiting drainage. Best suited only when topsoil issues are minimal.
• Recycled Concrete Mixes: Sustainable and eco-conscious, though consistency in drainage performance varies.

Benefits Worth Noting

A well-prepared sub-base ensures more than just drainage. It prevents turf wrinkling, eliminates soggy spots, and supports even load distribution, especially useful in homes with kids, pets, or outdoor furniture.

Plus, it extends the life of the grass system itself.

Common Pitfalls to Avoid

Over-compacting the base, using clay-based soil beneath, or skipping the drainage layer altogether often leads to standing water, bad odours, or premature turf failure. Many DIYers also forget edge compaction, resulting in shifting or sinking over time.

In short, synthetic grass is only as good as what’s under it. Laying the right foundation means creating a beautiful, functional outdoor space that works with (not against) Melbourne’s climate.

To create reliable drainage beneath synthetic grass in Melbourne’s ever-changing weather, selecting the right materials and layering method is critical.

You’ll need a thoughtful combination of items that transforms a lifeless patch into a durable, water-smart lawn.

Start with a Solid Base

Begin with a sub-base of crushed rock or road base no less than 75–100mm deep. Crushed rock with angular edges (like Class 2 or Class 3 aggregate) interlocks when compacted, creating stability while allowing water to flow freely between particles.

This layer forms the bedrock of your drainage system, which is essential in preventing waterlogging during Melbourne’s stormy months.

Add a Smoothing Layer

On top of that, apply 10–20mm of crusher dust or decomposed granite. This finer layer fills voids between the rocks and helps level the surface for smooth turf installation.

Because it still drains well, it won’t interfere with water flow. It will just make the turf sit flat, wrinkle-free, and ready for action.

Consider a Geo-Fabric Barrier

To block weeds while letting water pass, a geo-textile membrane (also called weed mat) can be rolled out beneath the sub-base.

This layer is especially important for long-term installations in garden-heavy suburbs, helping maintain clean drainage and preventing soil migration.

Drainage Channels or Piping (Optional)

For larger yards or sites prone to pooling, adding drainage cells, French drains, or perforated pipe systems beneath the base can significantly improve run-off management.

These features direct excess water away from the lawn into soak wells or stormwater connections.

Final Touch: Turf Backing and Perforation

Don’t overlook the turf itself. High-quality artificial grass, like what we supply at Reelgrass, includes perforations in the backing. These allow rain or hose water to pass through efficiently so the base materials can do their job below.

Recap: Best Layering System for Drainage in Melbourne

1. Geo-fabric (optional) – Blocks weeds, lets water through.
2. Crushed rock base – Rough, stable, and porous.
3. Crusher dust – Smooths the surface while maintaining flow.
4. Artificial turf with drainage holes – Channels water through quickly.
5. Optional drainage pipe or cell system – For complex or high-runoff areas.

This layered approach adapts perfectly to Melbourne’s diverse soil conditions and keeps your lawn looking pristine, rain or shine.

Melbourne is a patchwork of different soil types, council zones, and property sizes. When planning the sub-base for artificial grass, drainage isn’t a one-size-fits-all solution.

Homeowners need to factor in conditions on-site, local requirements, and approval pathways before rolling out turf.

Soil Conditions Across Melbourne

Melbourne’s soil varies widely from suburb to suburb. Inner-city areas often have clay-heavy soils that retain moisture, while outer suburbs like Hoppers Crossing or Geelong might see sandy loam or reactive clay.

Clay-Based Soils

Clay holds water, which means poor natural drainage. In these areas, drainage channels or deeper crushed rock bases are essential to prevent water from sitting beneath the turf.

Sandy or Loamy Soils

These soils drain quickly but may lack compaction strength. Underlay in these zones should focus on creating firmness through added crushed rock and geo-fabric reinforcement.

Ideal Lawn Sizes and Slopes

Drainage planning changes dramatically based on lawn size and gradient.

Small Yards (Under 50m²)

Small areas can typically rely on basic crushed rock and dust layers if the soil isn’t water-retentive. Drainage holes in the turf usually suffice without additional infrastructure.

Medium to Large Lawns (50–200m²)

Wider installations benefit from deeper crushed rock and consideration for surface runoff direction. Incorporating sloped grading helps water flow away from the home.

Sloped or Uneven Ground

For steep gradients, tiered bases or retaining edges may be necessary. Professional levelling ensures water doesn’t settle at the lowest point.

Local Council Recommendations

While artificial grass doesn’t typically require full development permits, it’s wise to check with your local council, especially when altering stormwater flow or hardscaping in front yards.

Front Yard Rules

Some councils, including those in Melbourne’s inner north and coastal areas, discourage excessive hardscaping visible from the street. Using permeable underlay materials like crushed rock helps meet soft landscaping ratio requirements.

Drainage Infrastructure

In flood-prone areas, councils may request drainage plans if the lawn interferes with existing systems or alters water flow to neighbouring properties.

When Permits or Approvals Might Be Needed

Artificial grass itself rarely requires a permit, but if your project includes excavation, levelling, or new drainage lines, approvals may apply.

• Excavation deeper than 600mm may fall under local building code scrutiny.
• Stormwater redirection into sewer systems or council drains needs approval.
• Shared driveways or body corporate areas might require written approval from all parties involved.

Always consult your council’s landscaping or planning department if unsure. Reelgrass clients often ask us to liaise directly with councils or builders to simplify this step.

Getting drainage right under artificial grass isn’t just smart, it’s non-negotiable for long-lasting performance in Melbourne’s unpredictable climate.

Whether it’s a backyard play space or a peaceful garden retreat, proper groundwork sets the stage for a lush, low-maintenance lawn that works year-round.

Here’s what to remember:

• Use crushed rock as a solid, water-permeable base.
• Apply crusher dust or granite sand for levelling and smoothness.
• Include geo-fabric to block weeds and stabilise layers.
• For sloped or clay-heavy sites, add drainage channels or pipes.
• Always check council guidelines when changing runoff or soil levels.
• Size, soil type, and location all affect sub-base choice and depth.

Every lawn is different, and your drainage solution should match the conditions beneath it. Rather than guess, consult with a professional who understands local ground conditions and installation best practices.

Choosing the right base for artificial grass is an important construction detail, but it’s also a long-term investment in your outdoor space.

At Reelgrass, we’ve spent over 15 years perfecting the art of drainage, installation, and premium turf supply across Melbourne.

Our team knows the soils, the weather, and exactly what works underfoot.

Avoid the guesswork. Avoid the mess. Avoid costly fixes down the line.

With a legacy built on trust, innovation, and real-world results, Reelgrass stands as Melbourne’s go-to name for synthetic turf solutions that perform as beautifully as they look.

Whether you’re going DIY or want expert installation, we’ll help you get the foundation spot-on.

Call us today on 1300 306 389 or send us your plans for a free quote –  usually within 3 business days.

Let’s build a better backyard from the ground up!