Silica Sand vs Rubber Crumb Infill for Australian Backyards

What infill does in a backyard lawn

Infill is the loose material brushed down into the pile after the turf is laid. You barely see it once it settles, but it does more work than most people expect. It weighs the turf down so the backing can't ripple as it expands in summer heat, it props the fibres up so they don't lie flat under foot traffic, and it shields the backing from UV so the whole lawn lasts longer.

Pile height gets most of the attention when people shop for turf, and our pile height guide covers that choice in detail. Infill is a separate decision, and it affects how hot the lawn gets, how it smells with a dog on it, and what washes off it in a storm.

Home lawn infills in Australia fall into two families: mineral infills, led by silica sand, and rubber infills, led by rubber crumb.

Silica sand in plain terms

The sand used for turf is washed, kiln-dried silica sand with a fairly even grain size. Kiln drying matters because damp sand clumps and won't brush evenly down into the pile. Ordinary builder's sand or brickie's sand is the wrong product here, since it holds moisture and fine particles that can clog the drainage holes in the backing.

Silica sand is the standard infill for residential turf in Australia, and there are good reasons for that. It's heavy, so a modest amount ballasts the lawn well. It's cheap and sold at most landscape suppliers. It drains freely. And being a natural mineral, it adds no plastic to your yard.

The downsides are real but manageable. Sand is firm, so it adds little cushioning of its own. On a sparse, low-density turf it can show at the surface as a sandy look between the blades. It also compacts over the years, and a busy lawn needs a brush and an occasional top-up to stay springy.

Rubber crumb in plain terms

Rubber crumb is granulated rubber, most often SBR (styrene butadiene rubber) made from recycled car and truck tyres. You'll also see EPDM and TPE granules, which are manufactured rubbers and polymers sold as cleaner, more colour-stable alternatives at a higher price.

Crumb exists because of sport. On a football or hockey pitch, players need shock absorption when they fall and a consistent bounce from the ball, so fields are usually built with a layer of sand for stability topped with rubber for give. Nearly all of the research on rubber crumb comes from those fields.

In a backyard, the case for crumb is much weaker. The lawn doesn't need the shock absorption of a sports field, and the pile on a 30-40mm landscape turf already gives a softer feel underfoot than a short sports surface.

Side-by-side comparison

Factor	Silica sand	Rubber crumb (SBR)
Main job	Ballast and fibre support	Cushioning for sport
Heat in full sun	Lighter colour, runs cooler	Black granules absorb more heat
Weight	Heavy, stays put	Light, floats and scatters
Stormwater runoff	Natural mineral	Plastic and rubber particles
Pets	Easy to rinse, works with antimicrobial coatings	Can hold odours, dogs may track it inside
Smell	None	Can smell of rubber on hot days
Cost	Low	Usually higher
Common use	Residential lawns	Sports fields

Heat: where the difference shows

All synthetic turf gets hot in direct summer sun, whatever the infill. The yarn and backing do most of that heating, so switching infill won't turn a hot lawn into a cool one.

Black rubber granules absorb a lot of solar energy, so under the same sun they heat up more than lighter mineral infills. Tan-coloured sand reflects more light and doesn't add that extra load. If you have kids or dogs using the lawn barefoot through January, that's a point for sand before you consider anything else.

Shade, turf colour and a quick hose-down on hot afternoons still matter more than infill choice.

Runoff and what escapes the yard

This is the biggest practical difference for a home lawn in Australia. Rubber crumb is light enough to float, so heavy rain carries it out of the pile, off the edges and into gutters and stormwater drains.

The NSW Chief Scientist and Engineer's independent review of synthetic turf in public spaces, released in 2023, found evidence of both rubber infill and turf fibres in NSW waterways. Expert advice quoted in the review estimated that a synthetic field without containment measures can wash tens to hundreds of kilograms of infill a year into stormwater or waterways. The review also flagged gaps in what's known about the chemical makeup of imported rubber crumb, including heavy metals and polycyclic aromatic hydrocarbons, and recommended further research rather than a ban. The European Union has gone further and moved to restrict loose polymer infill.

Those findings relate to sports fields, which use far more infill than any backyard. Still, the direction is clear. Sand is heavy, sinks rather than floats, and is a natural mineral if some does wash away. Our guide on whether artificial grass is bad for the environment goes through the wider research.

Infill for dogs and pets

Sand works well with pets. Urine passes down through it and out through the backing, and a rinse with the hose flushes it through again. Rubber crumb is less forgiving. The granules sit loose on top, stick to damp paws and end up on the couch, and some owners find crumb hangs on to odour on hot days.

For a pet lawn there are two sand-adjacent upgrades worth knowing about:

• Antimicrobial-coated sand is ordinary silica sand with a coating that slows the bacteria behind urine smell. It costs more than plain sand and won't replace regular rinsing, but it buys some slack between hose-downs.
• Zeolite is a natural mineral with a porous structure that traps ammonia, the compound behind the sharp urine smell. Many owners mix it into the toilet corner under or alongside sand, rather than using it across the whole lawn.

The turf matters as much as the infill. Pet Premium Super uses a yarn with a silver-based antimicrobial treatment that, in the manufacturer's testing, gives up to a 99% reduction of microbes, and the manufacturer states its punch-hole backing drains up to around 2,000mm per hour. Both claims come from APT's own testing rather than independent trials, so pair them with a sensible rinsing routine. Our turf for pets page and the longer best artificial grass for dogs guide cover the rest of a pet setup.

How much infill and how to spread it

The amount depends on pile height, density and the product's own guidance, so check that first. Taller pile holds more infill, and a dense turf needs less to stand up. As a rough rule, you want the infill to sit low in the pile, supporting the fibres at the base, with a good length of blade still showing above it.

Spread it with a drop spreader or by hand in thin passes, brushing against the grain with a stiff broom after each pass so it works down to the backing instead of sitting on top. Kiln-dried sand can raise some fine dust when bags are tipped, so a basic dust mask while pouring is sensible. Our how to lay artificial turf guide walks through this step as part of the full install.

On cost, sand is a small line item next to the turf. General Australian market pricing for DIY base materials, including crusher dust, weed membrane, joining tape, pins and sand infill, usually lands around $10-20/m². Turf itself runs about $15-30/m² for budget, $30-45/m² for mid-range and $40-60/m² for premium, supply only and including GST. Browse our turf range and see current pricing on each product page, where picking a length and quantity gives you an instant price.

Our pick for an Australian backyard

For nearly every home lawn, go with kiln-dried silica sand. It's cheap, heavy, runs cooler than black rubber, drains well and keeps plastic out of your stormwater. Add antimicrobial-coated sand or zeolite if a dog uses the yard as a toilet. Leave rubber crumb to sports fields, where its cushioning earns its place.

Frequently asked questions

Can I use normal builder's sand as turf infill?

It's best avoided. Builder's and brickie's sand hold moisture and fine clay particles, which clump in the pile and can clog the drainage holes in the backing over time. Washed, kiln-dried silica sand flows evenly into the pile and drains freely, and it's sold in bags at most landscape suppliers.

Is rubber crumb softer for kids to play on?

Rubber crumb adds some give, which is why sports fields use it, but on a backyard lawn the pile height and a good base do most of the cushioning. A 30-40mm pile over a well-compacted base already feels soft underfoot. For a play area with a fall height, such as under a swing set, a proper impact-absorbing underlay does far more than switching infill.

Does infill make artificial grass hotter?

The turf yarn and backing drive most of the heat, so every synthetic lawn gets hot in full summer sun regardless of infill. Black rubber crumb adds to that because it absorbs more solar energy than lighter sand. Sand won't make turf cool, but it avoids adding extra heat, and shade plus a quick hose-down help more than either infill.

How often does sand infill need topping up?

A lightly used lawn can go several years without it. A busy lawn with kids or dogs usually needs a top-up every two to three years as sand migrates and compacts. If the fibres start lying flat or the backing becomes visible when you part the blades, it's time to brush in more.