About STP ShaliDrain 8F

ShaliDrain 8F is STP Limited’s HDPE dimpled cavity-drain board, supplied with a 110 GSM polypropylene geotextile fleece pre-bonded to the dimpled face. The 8 mm dimples hold a continuous air gap (around 5 litres per square metre) between the structure and the surrounding earth once the board is fixed in place — and that gap is the entire point. Ground water doesn’t stop at a waterproofing membrane just because one exists; it keeps pushing, and over years that hydrostatic head is what eventually finds a pinhole, a lap joint, or a construction-joint weak spot. ShaliDrain 8F intercepts that water in the cavity, runs it down the dimple channels at a tested 4.6 l/s/m (EN 12958), and hands it off to a perimeter drain or sump before it can pressurise the membrane. The fleece does the second job, keeping soil fines out (95-micron opening size, EN ISO 12956) while still passing water at 120 mm/s, so the channel doesn’t silt up within a monsoon or two.

For Delhi NCR sites this matters in practice, not just on paper. A good share of basement waterproofing complaints Space Arc gets called to inspect trace back not to membrane failure but to backfill damage on an unprotected membrane, or hydrostatic pressure a membrane was never meant to resist alone. ShaliDrain 8F sits as the protection-and-drainage layer between a properly installed bituminous, PU or cementitious waterproofing system and the earth — standard practice wherever the water table is high or backfill gets compacted by machine rather than by hand. Rated -30°C to +80°C and resistant to acids, alkalis and common soil contaminants, it’s also approved for drinking-water contact per STP’s literature, which matters on reservoir and other water-retaining structure work as much as on ordinary basements.

The technical insight

Two numbers matter more than the rest of the datasheet: 230 kN/m² compression strength and 4.6 l/s/m drain flow under EN 12958. The compression figure is what stops an 8 mm dimple from crushing flat under machine-compacted backfill — a real failure mode with thinner, cheaper dimple sheets. The flow figure is tested under load rather than free-standing, which is the honest way to state it, since an uncompressed drainage number tells you little about actual site performance. Reaction to fire is Class ‘E’ — HDPE is combustible, which is fine below grade but is why it’s never specified for above-ground or exposed applications. And the 30-day UV exposure limit in the datasheet is a hard backfilling deadline, not a suggestion: HDPE embrittles under sustained sunlight.

Where it is used

• Basement and retaining wall drainage/protection behind bituminous, PU or cementitious waterproofing systems
• Metro, rail and road tunnel lining protection against ground water and soil pressure
• Underground and basement car parking structures
• Dams and other water-retaining hydraulic structures
• Highway, embankment and road sub-structure drainage
• Pipeline trench wrapping and protection
• Terrace and podium (planter bed / green roof) drainage layers
• Raft foundations, laid on prepared soil as a clean working surface in place of lean concrete blinding

Key advantages

• Continuous air gap and 4.6 l/s/m tested drain flow relieves hydrostatic pressure the membrane would otherwise carry alone
• 230 kN/m² compression strength survives machine-compacted backfill without the dimples crushing flat
• Bonded 110 GSM fleece filters soil fines (95-micron opening) so the drainage channel stays clear long-term
• Resistant to acids, alkalis and common solvents found in soil and groundwater
• Root-resistant, making it suitable under terrace and podium gardens
• Approved for drinking-water contact and rated non-toxic, non-polluting
• Lightweight, flexible rolls a normal site crew can handle and lap without special equipment
• Wide service range (-30°C to +80°C) covers extreme site and climate conditions

Limitations & considerations

• It is a drainage/protection composite, not a waterproofing membrane — it must go over a proper membrane or coating system, never replace one
• UV-sensitive: must be backfilled or covered within 30 days of exposure, which needs sequencing discipline on site
• Class ‘E’ fire reaction means HDPE is combustible, so it isn’t suitable for exposed, fire-rated or above-ground applications
• Substrate must be smooth and free of protrusions before laying, or point loads can puncture the dimples over time
• Drainage continuity depends entirely on lap and joint quality — a rushed installation crew is the most common cause of underperformance
• Standard 2.3 m roll width means irregular basement geometries generate cutting waste that should be allowed for at estimation stage

Selection & best practice

Specifications

Industry use cases

How we position STP ShaliDrain 8F

Within STP’s own range, ShaliDrain 8F is meant to sit alongside a primary waterproofing system, not replace one — STP’s Shali-range bituminous membranes and liquid-applied PU/acrylic coatings still do the actual water-barrier job, while this board protects and drains behind them. In the wider Indian market, the closer comparisons are other HDPE/PP cavity-drain composites such as Sika’s SikaDrain range rather than Fosroc: Fosroc’s mainstream waterproofing catalogue (Proofex, Nitoproof) is built around membranes and coatings, and doesn’t carry a directly equivalent dimpled drainage board in its standard India line-up, so specifiers typically weigh ShaliDrain 8F against other drainage-composite makers rather than against Fosroc.

Related Waterproofing products

View all Waterproofing products →