A drainage mat is a non-woven geotextile membrane that filters water while keeping soil and aggregate layers separate.
On most landscaping jobs, drainage failures come down to one problem: the wrong material between the subgrade and the drainage layer. Crushed rock on its own clogs with fines within a few years, and the drain stops working.
This guide compares drainage mats against crushed rock aggregate for retaining walls, paving, artificial turf and garden beds. We cover which geotextile weight to choose, how to install a drainage mat properly, and where to source rolls in bulk for trade and council projects.
Looking for drainage mat products? Browse the full product range at All Stake Supply or see the erosion control range for geotextile membranes, ag pipe and fastening pins.
A drainage mat (also called drain matting or geotextile filter fabric) is a permeable, non-woven polypropylene membrane. It lets water pass through while blocking soil particles, sand and silt from migrating into the drainage layer below.
Crushed rock aggregate has been the default drainage solution in Australian landscaping for decades. It works initially. But fine particles from the surrounding soil gradually fill the air voids between stones, and within three to five years a gravel drainage layer without geotextile wrapping loses most of its flow capacity.
That clogging problem is why most current specifications require a geotextile membrane wrapped around or layered over aggregate drainage systems. The mat handles filtration. The rock provides the void space for water flow.
Landscapers often ask whether they can skip the geotextile and just use more gravel. The short answer is no. Here is how the two materials compare across the factors that matter on site.
| Factor | Drainage Mat | Crushed Rock Alone |
|---|---|---|
| Soil separation | Blocks particles down to 90 microns | No separation, fines migrate in |
| Installation speed | Roll out and pin, 15 to 20 minutes per section | Spread, compact and level over hours |
| Lifespan without maintenance | 20+ years if UV-protected once buried | 3 to 5 years before clogging starts |
| Material cost per m² | Lower (fabric + pins) | Higher (rock + cartage + compaction) |
| Lateral load on retaining walls | Minimal | Significant weight against the wall |
Most trade landscapers now use both: a drainage mat wrapped around a gravel bed or ag pipe, rather than one or the other alone. The geotextile handles filtration while the aggregate provides the void space and structural support.
A 100gsm non-woven geotextile is the standard weight for residential drainage behind retaining walls and under paving. All Stake Supply stocks filter fabric geotextile drainage membrane rolls from 0.60m to 4m wide.
The single most common use for drainage mats in Australian landscaping is behind retaining walls. Water pressure building up behind a wall is the number one cause of retaining wall failure, and a drainage mat is the first line of defence.
Australian Standard AS 4678 covers the design and construction of retaining walls and includes requirements for adequate drainage provisions. A properly installed geotextile drainage layer satisfies those drainage requirements while protecting the wall from root intrusion and soil movement that can compromise wall integrity over time.
Skipping the drainage mat in this setup means the gravel backfill will eventually clog with clay fines. Once that happens, hydrostatic pressure builds and the wall starts to lean or crack.
For large-scale retaining wall projects, geotextile filter tubes placed at the base of the wall provide additional water collection where flow rates are highest.
Drainage mat is equally important under any hard surface. When water cannot drain through or around a paved area, it pools on the surface or undermines the base course from below. Both problems lead to cracking, shifting and premature failure.
Under artificial turf, the drainage mat sits between the compacted crushed rock base and the turf backing. It stops the base course from punching through the turf and provides a consistent drainage plane so water moves laterally to the edges.
Under paving, the mat goes between the natural subgrade and the road base. This prevents the subgrade pumping up into the base under traffic loads, which is the most common cause of paving failure in clay soils across NSW and Queensland.
Drainage mats are measured in grams per square metre (gsm). The weight determines the mat's filtration rate, tensile strength and durability.
Heavier is not always better. The right weight depends on the soil type and the load the mat will carry.
For most landscaping projects, a 100gsm non-woven geotextile roll is the right choice. All Stake Supply stocks these in widths from 0.60m (narrow trenches) through to 4m (broad coverage for large sites).
Getting the installation right avoids waste and prevents gaps that let soil through. The process is straightforward, but a few details matter.
On sloped sites, always run the drainage mat up the slope and over the top by at least 300mm. Water running down the slope will slide between the mat and the soil if the top edge is not properly tucked and pinned.
The biggest installation mistake is cutting joins too tight. A 200mm overlap costs almost nothing in extra material but prevents soil from migrating through gaps at the seams. Use steel fastening pins every metre to stop the mat from shifting before the fill goes down.
For single residential jobs, most landscapers buy one or two rolls at a time. For subdivision work, council projects or commercial builds, buying in bulk from a dedicated supplier saves significantly on per-metre costs and avoids the delays of retail stock shortages.
All Stake Supply has stocked geotextile drainage membranes from their St Marys NSW warehouse since 1976. Every order ships complete. No partial deliveries holding up your site.
Geotextile products conform to relevant Australian Standards for geosynthetics, and All Stake can provide technical data sheets for any product in the range.
A drainage mat is a low-cost addition to any landscaping project that pays for itself by extending the life of the drainage system it protects. Whether you are backfilling a retaining wall, laying a base for paving, or installing artificial turf, a 100gsm non-woven geotextile membrane is the standard starting point.
For trade quantities and bulk pricing on geotextile drainage membrane rolls, contact All Stake Supply or browse the erosion control range online.
