Repair Systems — 01
Drainage cell systems — planter boxes and podiums
Technical product reference for modular polypropylene drainage cell systems used in planter box, green roof, and podium slab waterproofing remediation on Australian Class 2 strata buildings. Covers depth selection, void ratio, compressive strength, water retention cups, passive irrigation, filter fabric pairing, and brand comparisons.
What are drainage cell systems — planter boxes and podiums?
Drainage cell systems are modular, interlocking polypropylene panels placed between the waterproofing membrane and the growing medium in planter boxes, green roofs, and landscaped podium slabs. Their primary function is to create a permanent, non-clogging subsurface drainage void above the membrane — allowing excess water from irrigation and rainfall to flow laterally through the void to the drainage outlets, while the growing medium above retains only the moisture required for plant health. Without a drainage void, waterlogged growing medium sits directly on the membrane surface, promotes membrane degradation, prevents root aeration, and prevents excess water from reaching the outlet — all of which contribute to planter box failure and membrane damage over time.
Drainage cells replace the traditional coarse aggregate drainage layer used in conventional planter box construction. A 30mm drainage cell provides approximately the same drainage capacity as 150mm of coarse gravel aggregate, while adding only 2% of the gravel's weight to the structural slab — a critical advantage on podium slabs and roof decks where dead load is constrained. The reduced drainage layer depth also allows greater growing medium depth within the same overall planter box height, expanding the range of plants and tree species that can be used above the membrane.
Drainage cells are available in 20mm, 30mm, and 50mm depths — selected based on the required drainage flow rate, the growing medium depth, the loading conditions above, and the available build-up height within the planter box. Many drainage cell formats incorporate small water retention cups in the base of each cell — these cups retain a small volume of water below the drainage void level, creating a perched water table that provides passive irrigation to the growing medium during dry periods without retaining standing water on the membrane surface.
Product Reference
5 products — 5 brands — 20mm, 30mm, and 50mm modular polypropylene drainage cells — planter boxes, green roofs, and landscaped podium slabs — always specify with filter fabric above
Atlantis Flo-Cell
Modular polypropylene drainage cell — 20mm / 30mm / 50mm — Atlantis Corporation Australia
Modular polypropylene drainage cell — 20mm, 30mm, and 50mm depths — diamond cup water retention structure for passive irrigation — 85% recycled polypropylene — void ratio >90% — widely available nationally — planter boxes, green roofs, and podium slabs
Specifier Note
Confirm drainage cell depth against hydraulic design flow rate, planting load, and available build-up height before ordering. Always specify with filter fabric above.
System Description
Atlantis Flo-Cell is one of the most widely distributed modular polypropylene drainage cell systems in Australia, available in 20mm, 30mm, and 50mm depths through multiple national suppliers. Manufactured from 85% recycled polypropylene (15% proprietary materials), Flo-Cell is inert to soil-borne chemicals and bacteria, resistant to biological attack, and does not deteriorate under the permanently moist conditions of a planter box or podium garden. Void ratio exceeds 90% across all three depths. The distinctive diamond cup structure on the base of each Flo-Cell panel creates small water retention cups that hold a modest water volume below the main drainage void — providing a perched water table for passive irrigation of the growing medium above during dry periods. This passive irrigation feature reduces irrigation frequency and supports plant health in Australian summer conditions. Excess water above the cup level drains freely through the cell void to the outlets. Modular panels interlock in the same plane or at right angles, allowing rapid installation across the planter base with minimal cutting at edges. Confirmed specifications: 20mm — 400mm × 620mm × 20mm, 4 per m², compressive strength 90 t/m², flow rate 0.65 L/m² at 1% gradient; 30mm — 575mm × 575mm × 30mm, 3 per m², compressive strength 105 t/m², flow rate 1.41 L/m² at 1% gradient; 50mm — 575mm × 575mm × 50mm, 3 per m², compressive strength 155 t/m², flow rate 2.65 L/m² at 1% gradient.
Technical Properties
- Modular interlocking polypropylene drainage cell — 20mm, 30mm, and 50mm depths
- 85% recycled polypropylene — 15% proprietary materials — black
- Void ratio >90% — high drainage efficiency across all depths
- Diamond cup structure — passive irrigation water retention — perched water table below growing medium
- Compressive strength 90 t/m² (20mm) — 105 t/m² (30mm) — 155 t/m² (50mm)
- Inert to soil-borne chemicals and bacteria — biologically resistant
- Panels interlock in same plane or at right angles — cut to fit at edges
- Always specify with geotextile filter fabric above
Limitations
- Filter fabric is mandatory above — do not install without geotextile filter fabric covering the full cell area and lapping up planter walls
- Confirm required depth (20mm, 30mm, or 50mm) against drainage design flow rate, loading, and available build-up height before ordering
- Not a membrane protection product — protection board is separately specified below the drainage cells if required
- Confirm compressive strength against machinery access loads if bobcat or small tractor access is required during planting or maintenance
- Confirm current pricing and availability with local supplier before ordering
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Elmich VersiCell
Australian Made high-strength subsoil drainage cell — 30mm — Elmich Australia
Australian Made high-strength polypropylene subsoil drainage cell — 30mm — designed to withstand bobcat and mechanical equipment loads — interlocking modular panels — pre-assembled large panels for rapid installation — planter boxes, roof gardens, plaza decks, and podium slabs
Specifier Note
Confirm drainage depth requirement, mechanical access loads, and passive irrigation requirement with Elmich Australia before specifying.
System Description
Elmich VersiCell is an Australian Made high-strength polypropylene modular drainage cell used in the construction of roof gardens, plaza decks, basements, pond filtration systems, concealed drains, and planter boxes on Class 2 strata buildings. Its manufacture in Australia by Elmich ensures consistent supply without the import lead times of overseas-sourced products. VersiCell is specifically noted for its structural strength — designed to withstand loads imposed by mechanical equipment such as bobcats during planting and maintenance operations on large podium gardens and roof decks. This is a distinct advantage on commercial and large residential strata podium applications where bobcat access for spreading growing medium is required. Available in 30mm depth modules. Modules interlock in the same plane, at right angles to one another, or may be butted together — providing flexibility in layout across irregular planter floor areas. Large pre-assembled panels allow rapid installation and minimise on-site disruption — an advantage on strata remediation projects where access is limited and installation time is constrained. VersiCell does not incorporate the same diamond cup water retention structure as Atlantis Flo-Cell. It is primarily a structural drainage void product — focused on drainage efficiency and load capacity rather than passive irrigation. Where passive irrigation is a design requirement, confirm with Elmich whether VersiCell is appropriate or whether a cup-structured cell should be specified.
Technical Properties
- Australian Made — high-strength polypropylene — consistent domestic supply
- 30mm depth — interlocking modular panels
- Designed to withstand mechanical equipment loads (bobcats) — confirm load capacity with Elmich for specific machinery
- Interlock in same plane, at right angles, or butted together — flexible layout
- Large pre-assembled panels — rapid installation — reduced on-site disruption
- High surface void area — efficient water capture and discharge
- Resistance to biological attack and soil-borne chemicals
- Wide applications: planter boxes, roof gardens, plaza decks, basements
- Always specify with geotextile filter fabric above
Limitations
- Filter fabric is mandatory above — do not install without geotextile filter fabric
- 30mm depth only — where 20mm or 50mm is required, specify Atlantis Flo-Cell or Ausdrain instead
- No water retention cup structure — confirm with landscape architect if passive irrigation is a design requirement
- Confirm current product specifications, compressive strength, and pricing with Elmich Australia before specifying
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Ausdrain Drainage Cell
Modular polypropylene drainage cell — 30mm / 50mm — Ausdrain Australia
Australian drainage cell — 30mm and 50mm depths — creates permanent non-clogging void between slab and growing medium — 98% weight saving over gravel — high compressive strength allows truck delivery of growing medium once 300mm placed above — planter boxes, roof gardens, and podium slabs
Specifier Note
Confirm drainage depth, compressive strength, and machinery access requirements with Ausdrain before specifying.
System Description
Ausdrain produces Australian drainage cells in 30mm and 50mm depths, specifically marketed for planter boxes, roof gardens, and landscaped podiums on Class 2 strata and commercial building projects. Ausdrain drainage cells create a permanent, non-clogging void between the concrete slab and the growing medium above — the large surface and internal void space enables superior drainage efficiency compared to coarse gravel, with approximately 98% weight saving over the equivalent gravel drainage layer. A key practical advantage noted by Ausdrain is that once a minimum of 300mm of growing medium has been placed over the drainage cell and filter fabric, the structural strength of the cell layer is sufficient to allow trucks and machinery to drive over the growing medium surface for further soil delivery — significantly simplifying growing medium installation on large podium garden projects. Confirm the required growing medium depth for machinery access with Ausdrain before specifying. The 50mm depth cells provide the highest flow rate in the Ausdrain range — appropriate for large podium gardens with heavy planting, extensive irrigation systems, or high-rainfall exposure where a greater drainage reserve capacity is needed.
Technical Properties
- 30mm and 50mm depths — confirm depth against drainage design and build-up height
- Permanent non-clogging drainage void — will not collapse or distort under load
- 98% weight saving over equivalent gravel drainage layer
- High compressive strength — allows machinery and truck access once 300mm growing medium placed above
- Suitable for planter boxes, roof gardens, landscaped podiums, and retaining wall drainage
- Australian supply — confirm current availability with Ausdrain
- Always specify with geotextile filter fabric above
Limitations
- Filter fabric is mandatory above — do not install without geotextile filter fabric
- 30mm and 50mm only — where 20mm is required, specify Atlantis Flo-Cell or DRAINmasta DrainCel instead
- Confirm compressive strength and machinery access growing medium depth with Ausdrain for the specific project loading
- Confirm current product specifications and pricing with Ausdrain before specifying
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
DRAINmasta DrainCel
Modular drainage cell — 20mm / 30mm — horizontal and vertical applications — Polyfabrics Australia
Modular drainage cell — 20mm and 30mm — water retention cups for passive irrigation — suitable for horizontal planter box and roof garden drainage and vertical retaining wall drainage — geosynthetics specialist supply through Polyfabrics Australia
Specifier Note
Confirm drainage depth, application type (horizontal or vertical), and filter fabric pairing with Polyfabrics Australia before specifying.
System Description
DRAINmasta DrainCel is a modular drainage cell produced and distributed by Polyfabrics Australia — a geosynthetics specialist with civil engineering expertise in retaining wall design, drainage design, and geotechnical applications. Available in 20mm and 30mm depths as 1.2m² panels. DrainCel features water retention cups in the base of each cell that provide passive irrigation by creating a perched water table below the growing medium — retaining a small water volume during dry periods while allowing excess irrigation and rainfall to drain freely. A distinguishing feature of the DRAINmasta range is its confirmed suitability for vertical retaining wall drainage applications as well as horizontal planter box and roof garden use — the high void ratio and flow rate combined with excellent compressive strength make it effective when installed vertically behind retaining walls within planter box and podium garden structures. This is relevant on strata planter boxes where the vertical planter walls may require drainage as well as the horizontal floor. As a geosynthetics specialist, Polyfabrics Australia can provide technical advice on drainage cell selection, filter fabric pairing, and full subsurface drainage system design — a useful resource for complex or large-scale strata podium garden remediation projects.
Technical Properties
- 20mm and 30mm depths — 1.2m² panels
- Water retention cups — passive irrigation — perched water table below growing medium
- High void ratio — high flow rate — efficient water capture and discharge
- Confirmed suitable for horizontal and vertical drainage applications
- Geosynthetics specialist supply — technical drainage design advice available from Polyfabrics
- Available through Polyfabrics Australia — direct supply
- Always specify with geotextile filter fabric above (horizontal) and adjacent (vertical)
Limitations
- Filter fabric is mandatory above for horizontal applications and adjacent to the cell for vertical wall applications — do not omit
- Confirm 20mm vs 30mm depth against drainage design flow rate and available build-up height
- Confirm compressive strength against loading for the specific application
- Confirm current product specifications, panel sizes, and pricing with Polyfabrics Australia before specifying
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Generic Modular Drainage Cell
Generic modular polypropylene drainage cell — 20mm / 30mm — trade supply
Generic modular polypropylene drainage cell — 20mm and 30mm — widely available through landscape and drainage trade suppliers nationally — diamond cup water retention structure — budget specification for residential and light commercial planter box and roof garden applications
Specifier Note
For residential and light commercial planter box applications, widely available generic cells are appropriate. For commercial podium gardens, heavy loading, or machine access, specify a branded product with confirmed compressive strength.
System Description
Generic modular polypropylene drainage cells in 20mm and 30mm depths are widely available through landscape, drainage, and construction trade suppliers across Australia under multiple brand names. These panels are dimensionally and functionally similar to branded products — high-strength polypropylene, interlocking modular panels, diamond cup water retention structure, high void ratio, and biological resistance. They are manufactured to consistent specifications and have been used successfully across large-scale projects in Australia. Generic drainage cells are the standard budget specification for residential and light commercial planter boxes and roof garden applications on Class 2 strata buildings where the specific brand of drainage cell is not critical to the project specification. Project Material supplies both 20mm and 30mm cells in 1.21m² panels (1100mm × 1100mm) at competitive pricing nationally. Defined Style supplies similar products in Queensland and nationally. For high-specification commercial podium garden projects, heavy machine-access applications, or projects requiring documented brand and compressive strength certification, specify a branded product (Atlantis Flo-Cell, Elmich VersiCell, Ausdrain, or DRAINmasta DrainCel) with a confirmed TDS rather than a generic trade cell.
Technical Properties
- Modular interlocking polypropylene drainage cell — 20mm and 30mm depths
- Diamond cup water retention structure — passive irrigation
- High void ratio — biological and chemical resistance
- Panel size typically 1100mm × 1100mm — 1.21m² per panel
- Widely stocked through landscape and drainage trade suppliers Australia-wide
- Always specify with geotextile filter fabric above
Limitations
- Filter fabric is mandatory above — do not install without geotextile filter fabric
- Confirm compressive strength with supplier before specifying where machinery access or heavy loading is required — generic products may not have independently tested compressive strength documentation
- For high-specification or commercial applications, specify a branded product with a confirmed TDS
- Confirm current product availability, panel dimensions, and pricing with local supplier before ordering
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Drainage cell system comparison
Side-by-side comparison of drainage cell systems covered on this page. Confirm all product selections against the current manufacturer TDS before specifying.
| Product | Brand | Available depths | Compressive strength | Water retention cups | Machine access confirmed | Australian made | Key restriction |
|---|---|---|---|---|---|---|---|
| Atlantis Flo-Cell | Atlantis Corporation | 20mm, 30mm, 50mm | 90–155 t/m² by depth | Yes — diamond cup passive irrigation | Confirm with supplier for specific depth | No — 85% recycled PP | Most widely distributed — confirm depth against flow rate and build-up height — filter fabric mandatory above |
| Elmich VersiCell | Elmich Australia | 30mm | Confirm with Elmich — designed for bobcat loads | No — structural drainage void, no cup structure | Yes — specifically designed for mechanical equipment loads | Yes — Australian Made | 30mm only — no passive irrigation cup — confirm with landscape architect if passive irrigation is required — filter fabric mandatory above |
| Ausdrain | Ausdrain Australia | 30mm, 50mm | Confirm with Ausdrain — high compressive strength | Confirm with Ausdrain | Yes — truck access once 300mm growing medium placed above | Australian supply | 30mm and 50mm only — confirm machinery access growing medium depth with Ausdrain — filter fabric mandatory above |
| DRAINmasta DrainCel | Polyfabrics Australia | 20mm, 30mm | Confirm with Polyfabrics | Yes — water retention cups | Confirm with Polyfabrics | Australian supply | Horizontal and vertical wall drainage — geosynthetics specialist supply — filter fabric mandatory above and adjacent for vertical use |
| Generic Drainage Cell | Project Material / various | 20mm, 30mm | Confirm with supplier — may not be independently tested | Yes — diamond cup in most formats | Confirm with supplier | Various — confirm with supplier | Budget specification — residential and light commercial — for commercial or heavy loading specify branded product with confirmed TDS — filter fabric mandatory above |
Filter fabric is mandatory above every drainage cell installation — without it the cells will clog and fail
Geotextile filter fabric must be placed over the full surface of the drainage cell layer — covering every panel and lapping up the planter box walls — before growing medium is placed above. Without filter fabric, fine particles from the growing medium migrate down into the drainage cell void with each irrigation and rainfall event, progressively clogging the drainage paths. Once clogged, drainage cells cannot be cleaned or restored — the growing medium and cells must be completely removed and replaced. Filter fabric is not optional and is not a value-engineering reduction — it is a mandatory component of every drainage cell installation. See the Filter Fabric page for geotextile filter fabric specification and selection.
Drainage cells must be installed above a correctly waterproofed and inspected membrane — not as a substitute for waterproofing
Drainage cells are a subsurface drainage product — they sit above the waterproofing membrane and manage the movement of water within the planter box system. They are not waterproofing products and do not protect the structural slab from water ingress. The waterproofing membrane below the drainage cells must be correctly specified (root resistant where plants are to be grown above), correctly installed, flood tested, and confirmed defect-free before the drainage cells are placed above it. Placing drainage cells over an uninspected, defective, or non-root-resistant membrane will not prevent long-term water ingress into the structure below. Confirm the waterproofing membrane specification on the Root Resistant Membranes page before specifying drainage cells.
Confirm structural loading with the engineer before specifying a planter box system on an existing podium slab
On existing Class 2 strata podium slabs and roof decks, the structural capacity for a new or replacement planter box system must be confirmed with a structural engineer before the system is specified. The combined dead load of the waterproofing membrane, protection board, drainage cells, filter fabric, growing medium, and plant material must be within the slab's design load capacity. Even with drainage cells substituting gravel (98% weight saving in the drainage layer), the growing medium and plants impose significant dead loads — particularly where deep-rooted plants or trees are specified. Older podium slabs may have been designed for minimal or no planting load. Do not assume an existing slab can carry a new planter box system without engineering confirmation.
Drainage cell depth selection — confirm with the hydraulic engineer and landscape architect before ordering
The correct drainage cell depth (20mm, 30mm, or 50mm) must be confirmed against three criteria before ordering: the hydraulic design flow rate required for the drainage area and rainfall intensity, the available build-up height within the planter box (membrane surface level to the top of the planter wall), and the compressive strength required for any machinery access. These three criteria are rarely all equal — the deepest available cell is not always the correct specification. A 50mm cell that exceeds the available build-up height leaves insufficient depth for growing medium. A 20mm cell that cannot handle the design rainfall flow rate will cause waterlogging above the cells. Confirm depth selection with the hydraulic engineer and landscape architect before placing the order.
Disclaimer
This page provides general technical information only. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, hydraulic design flow rate, drainage cell compressive strength requirements, available build-up height, structural loading confirmation from the engineer, landscape architect planting specification, and NCC requirements. Geotextile filter fabric is mandatory above all drainage cell installations. Drainage cells are subsurface drainage products and are not waterproofing — the waterproofing membrane below must be correctly specified, installed, and flood tested before drainage cells are placed above. Do not rely on this reference as a substitute for professional hydraulic engineer, structural engineer, landscape architect, or waterproofing consultant advice.