STP ShaliDrain 10
A 10mm HDPE dimpled drainage board that keeps groundwater and soil pressure off your basement waterproofing — engineered protection you install dry, in a day, not a week.
What is it?
STP ShaliDrain 10 is a high-density polyethylene (HDPE) sheet moulded into 10mm-high dimples, forming a drainage cavity and protective buffer between a structure and the earth around it.
Where is it used?
Basement retaining walls, metro and rail tunnel linings, highway and hill-road embankments, underground parking structures, dam faces, buried pipelines, and terrace or podium gardens.
Why use it?
It shields the waterproofing membrane underneath from puncture by backfill, sharp aggregate, and root growth, while its dimples channel incoming groundwater down and away, cutting the hydrostatic pressure that builds against a wall or slab.
How is it applied?
Rolled out dry with the dimples facing the wall or the ground, fixed with plastic anchor profiles or adhesive, overlapped 20-30cm at every joint, and sealed with hot-air welding or insulated tape before backfilling.
About STP ShaliDrain 10
Any basement in Delhi NCR or a metro line running under a monsoon-fed water table faces the same problem twice over: keep water out, and keep the waterproofing that’s doing that job from getting torn apart during backfilling. A coat of membrane alone doesn’t survive contact with compacted earth, stone chips, or root growth for very long. STP’s ShaliDrain 10 is the mechanical layer that goes over the membrane to take that abuse instead — a rugged, dimpled HDPE board manufactured in India under STP’s Shali product family, alongside better-known names like Shalimastic and ShaliCoat.
The 10mm dimple profile isn’t just a cushion; it’s a plumbing system. Each square metre of board holds about 5 litres of open air-gap volume between the dimples, through which water — rated by STP at 3.5 L/m²/s in plain drainage and 200 L/min/m along a channel — can move freely to an outlet or drain pipe instead of pressing against the structure. At 700 gm/m² and rated to handle 300-400 kN/m² of compression, it’s built to sit under backfill without collapsing flat, and it stays workable across a genuinely wide range — -30°C to +80°C — which matters on sites that see both winter fog and a Delhi summer slab pour.
The technical insight
The numbers on the STP data sheet tell you what the board is actually doing on site. Tensile strength of >6 kN/m in the machine direction and >4 kN/m cross-machine (tested to EN 10319) means the sheet resists tearing while it’s being pulled taut and pinned during installation, not just once it’s buried. Elongation figures of 20% (MD) and 25% (CMD) under EN 12311-2 give it enough give to conform to an uneven substrate without splitting. The EN 12958 drainage figures — 3.5 L/m²/s in plain flow and 200 L/min/m along the board — are the ones a drainage designer actually sizes a weep-hole or perimeter drain against; undersizing the outlet defeats the point of the board however good the sheet itself is. The Class ‘E’ reaction-to-fire rating and W1 waterproof classification are also worth knowing if a specification calls for either, since not every cavity-drain board on the market carries both.
Where it is used
- Protecting waterproofed basement retaining walls from backfill damage and soil pressure
- Cavity drainage behind metro and railway tunnel linings
- Highway, expressway, and hill-road embankment drainage
- Underground and multi-level basement car park structures
- Dam and reservoir wall protection
- Drainage and mechanical protection around buried pipelines
- Terrace, podium, and roof garden drainage beneath planting media
- Retaining walls on sloped or hill-side plots
Key advantages
- Dry, mechanical fixing — no multi-day coat-and-cure cycle like liquid waterproofing systems
- Combines two jobs in one layer: membrane protection and active groundwater drainage
- Resistant to acids, alkalis, common site chemicals, and plant root penetration
- Non-toxic and cleared for use near drinking-water applications
- Functions across a -30°C to +80°C range, so it isn’t a fair-weather-only material
- STP rates shelf life at 25+ years when stored and installed correctly
- Compression rating of 300-400 kN/m² holds up under compacted backfill loads
Limitations & considerations
- It is a protection and drainage layer, not a waterproofing membrane by itself — it must go over a properly cured membrane, never in place of one
- UV exposure is capped at 30 days before backfilling; leaving it exposed longer degrades the HDPE
- The 2.3m roll width means corners, columns, and pipe penetrations need careful cutting and detailing to keep the drainage cavity continuous
- Lab-rated figures (27°C, 55% RH) carry a stated 5-20% tolerance, so treat data-sheet numbers as design guidance, not a site guarantee
- Hot-air welding of joints needs a trained installer with the right equipment — a sloppy joint reintroduces the puncture risk the board is meant to prevent
Selection & best practice
Get the substrate right before the board goes anywhere near it: loose material blown off, honeycombing and blowholes patched, and the waterproofing membrane fully cured. Lay ShaliDrain 10 with the dimples facing the wall on verticals and facing the ground on horizontals — reversing this by mistake is a common site error that quietly cancels the drainage function. Keep overlaps to a minimum of 20cm on walls and 30cm on horizontal runs, and weld or tape every joint rather than relying on the overlap alone. Because the 30-day UV clock starts as soon as the roll is unrolled, sequence the work so backfilling follows installation closely, and protect the sheet from sharp stone during backfill compaction.
Specifications
| Material | High-density polyethylene (HDPE) dimpled board |
| Dimple Height | 10 mm |
| Total Weight | 700 gm/m² (EN 9864) |
| Compression Strength | 300-400 kN/m² |
| Tensile Strength (MD / CMD) | >6 kN/m / >4 kN/m (EN 10319) |
| Drain Flow Capacity (plain) | 3.5 L/m²/s (EN 12958) |
| Flow Rate (channel) | 200 L/min/m (EN 12958) |
| Temperature Range | -30°C to +80°C |
| Pack Size | Rolls, 2.3 m width x 20 m length |
Industry use cases
Residential basements, Delhi NCR
Protecting tanked basement walls in bungalow and builder-floor construction from backfill damage while draining seepage away from the structure.
Metro & rail infrastructure
Cavity drainage behind tunnel segment linings and station box walls on underground transit projects.
Commercial basement parking
Multi-level basement car parks where retaining walls need both membrane protection and active drainage to the sump.
Highways & hill roads
Embankment and retaining-wall drainage on highway projects and hill-side road cuttings prone to seepage.
Terrace & podium landscaping
Drainage layer beneath planting media on podium gardens and green roofs, preventing waterlogging of the root zone.
Frequently asked questions
Does ShaliDrain 10 waterproof the structure on its own?
What’s the difference between ShaliDrain 10 and the 10F, 8F, or 12F versions in STP’s range?
How long can it sit exposed on site before we backfill?
Is it safe to use around a drinking-water structure?
What overlap and jointing is needed at the joints?
Can Space Arc supply and install this in Delhi NCR?
How we position STP ShaliDrain 10
ShaliDrain 10 sits in the middle of STP’s own cavity-drain range: step down to ShaliDrain 08 or 8F for lighter-duty terrace and garden work, or up to ShaliDrain 12F or the 30mm ShaliDrainCell 30 where hydraulic loads are heavier, such as deep podium decks or green roofs — the F-suffix boards typically add a bonded filter fabric for direct soil contact. It’s meant to be paired with an STP waterproofing membrane underneath, such as the ShaliHDPE or ShaliBond EPDM ranges. Fosroc doesn’t carry a direct like-for-like cavity-drain dimple board in its standard India catalogue — its closest overlap is the Proofex range of self-adhesive waterproofing membranes, which some specifiers pair with a separately sourced dimple board rather than a single-brand system. Other names that come up in comparison on Indian sites include Cosmos and imported Delta-MS boards; ShaliDrain 10’s advantage is a single, India-manufactured supply chain that pairs with STP’s own membranes for a matched system.
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