About STP ShaliDrain 12F

ShaliDrain 12F is a cuspated HDPE drain board from STP Limited, part of the ShaliDrain range alongside the 08, 8F, 10 and 10F boards and the heavier ShaliDrainCell 30. Its core is a dimpled HDPE sheet pressed to a 12 mm dimple height, laminated on one face with a 110 GSM polypropylene nonwoven geotextile. The dimpled face sits against the applied waterproofing membrane, forming a continuous drainage channel, while the bonded fleece filters groundwater through and keeps soil fines out. It is not a waterproofing product itself — it is the protection and drainage layer that lets an applied membrane survive backfilling and years of soil pressure without being punctured or clogged.

That protective role matters on NCR basements and podium structures, where loose murrum and compacted backfill routinely tear unprotected membranes, and clay-heavy soils silt up open drainage paths within a couple of monsoons without a filter fabric. ShaliDrain 12F handles both: the HDPE core absorbs backfill and soil pressure, rated to 250 kN/m² compression, while the fleece keeps the drainage void working over the structure’s life instead of blinding shut. The 12 mm dimple sits at the top of STP’s fleeced range, so it’s generally specified on deeper basements and higher hydrostatic-load walls, while 8 mm and 10 mm boards suit lighter terrace work.

The technical insight

The two numbers that matter most on a ShaliDrain 12F data sheet work against each other by design: compression strength and drain flow capacity. At 250 kN/m² — roughly what several metres of compacted backfill exert — the 12 mm dimples must stay open under sustained load, since a collapsed dimple is a dead drainage channel; that’s why dimple height and compression rating are always quoted together. The drain flow capacity of 3.1 x 10⁻³ m²/s (EN 12958) describes how much water the void between dimples carries away in-plane, which is the actual mechanism relieving hydrostatic pressure against the membrane rather than letting it build up. The 110 GSM geotextile fleece handles filtration, not drainage: its polypropylene fibres pass water (permeability 8 x 10⁻² m/s, EN 11058) while retaining fine soil particles outside, so the void inside stays clear. Worth flagging to site teams: the Class ‘E’ fire rating means it’s a thermoplastic like any HDPE product, so hot-works sequencing near exposed rolls should be managed accordingly, particularly in enclosed tunnel or basement work.

Where it is used

• Protection and drainage layer over basement and retaining-wall waterproofing before backfilling
• External drainage composite behind shotcrete or membrane linings in metro and road tunnels
• Sub-soil drainage beneath podium decks, terrace gardens and planter beds, avoiding root-zone waterlogging
• Drainage and protection layer under plaza decks and multi-level basement parking
• Subsurface drainage behind highway and road embankment retaining walls
• Drainage composite for dam and reservoir retaining walls
• Protection wrap for buried pipeline trenches
• Drained-surface alternative to a lean-concrete blinding layer under rafts and slabs

Key advantages

• 250 kN/m² compression rating keeps the drainage channel open under full backfill load
• Bonded 110 GSM geotextile filters fines while passing water, so the path stays clear over time
• Resistant to acids, alkalis, common solvents and plant roots found in local soils
• Manufacturer-rated service life beyond 25 years within pH 4–9, sub-25°C conditions
• Approved for use near drinking-water applications
• Lightweight, flexible rolls install faster than aggregate-and-pipe drainage build-ups
• Non-toxic and non-polluting, with no reported deterioration under soil
• One board covers both under-slab (horizontal) and wall (vertical) applications

Limitations & considerations

• UV exposure before backfilling or covering is capped at 30 days — installation sequencing has to keep pace
• Protects and drains only; it must be installed over a proper waterproofing membrane, never instead of one
• Class ‘E’ fire reaction rating means it’s a combustible thermoplastic, needing normal hot-works care near exposed rolls
• Drainage continuity depends on lap quality — under-lapped or poorly sealed joints create bypass points for silt and water
• Fixed 2.3 m roll width adds cutting and overlap wastage on irregular basement geometries
• Adds no structural strength and won’t bridge substrate cracks or defects, which must be pre-treated separately

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliDrain 12F

Within STP’s own range, ShaliDrain 12F is the heavier-duty end of the fleeced drain-board family — pair it with ShaliDrain 8F or 10F on projects mixing deep-basement walls with lighter terrace or shallow-fill zones, or step up to ShaliDrainCell 30’s high-impact polypropylene cell system where a roof garden or podium deck needs a deeper, load-bearing sub-soil drainage void rather than a thin dimpled sheet. It is specified alongside, never instead of, an STP waterproofing membrane or coating on the same wall, since the board’s job is to protect and drain, not to seal. In the wider market, the closest comparison is Fosroc’s Proofex Aquadrain drainage composite, which serves the same protect-and-drain role on basement waterproofing packages; a specifier already standardised on Fosroc’s Proofex membrane system may lean toward Aquadrain for single-source procurement, while projects prioritising the widest published EN-tested performance data and STP’s pan-India applicator network typically default to ShaliDrain 12F.

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