STP ShaliEPDM
Single-ply EPDM rubber membrane from STP Limited for roofs, basements and pond lining — engineered to stretch, recover and stay watertight through decades of Indian summers and monsoons.
What is it?
A black, single-ply preformed waterproofing membrane made from EPDM synthetic rubber, manufactured by STP Limited and supplied in 1.0 mm, 1.2 mm and 1.5 mm thicknesses.
Where is it used?
Exposed and covered roofs, basements and below-grade walls, reservoir and pond lining, green roofs, podiums and sports facilities across new-build and refurbishment projects.
Why use it?
Elongation above 300% with proven UV and ozone resistance delivers a 30–50 year service expectancy that bituminous felts cannot approach — one sheet, minimal seams, no flame on site.
How is it applied?
Loose-laid and ballasted, or bonded to a prepared substrate; sheets are joined with contact adhesive or self-adhesive EPDM splice tape, with vulcanisation tape available for below-grade seams.
About STP ShaliEPDM
ShaliEPDM is STP Limited’s single-ply waterproofing membrane based on ethylene propylene diene monomer (EPDM) rubber, produced as a preformed black sheet conforming to ASTM D4637 Type I. Unlike site-built liquid systems or multi-layer felts, the membrane arrives at site as a factory-made sheet of consistent thickness and tested properties — tensile strength above 9 MPa and elongation beyond 300% to ASTM D412 — so the quality of the waterproofing layer itself is settled before the first roll is opened. What remains in the applicator’s hands is substrate preparation and seam work, which is exactly where a disciplined installer earns the membrane’s 30–50 year service expectancy.
For Indian projects the material’s appeal is durability under abuse. EPDM shrugs off UV exposure and ozone attack that embrittle bituminous membranes within a decade, and it stays flexible at temperatures as low as −45°C, so thermal cycling between summer roof temperatures and winter nights does not fatigue it. Space Arc Engineering stocks ShaliEPDM in 1.0, 1.2 and 1.5 mm thicknesses and supports supply-and-apply enquiries across Delhi NCR and pan-India, including seam detailing review before work begins.
The technical insight
EPDM’s longevity comes from its polymer backbone. The ethylene-propylene chain is fully saturated — there are almost no residual double bonds for UV radiation or ozone to attack — which is why exposed EPDM roofs abroad have logged five decades of service without a protective coating. The diene component is confined to side groups used for cross-linking during vulcanisation, giving the sheet its rubber elasticity without leaving weak points in the main chain. That elasticity matters structurally: when a roof slab cracks or a joint opens, a membrane bonded across it must stretch locally by many times the crack width. With elongation above 300% and near-full elastic recovery, ShaliEPDM bridges that movement cycle after cycle instead of tearing, which is the failure mode that ends the life of stiffer, oxidised bituminous systems.
Where it is used
- Exposed waterproofing of RCC roofs on commercial and industrial buildings
- Basement rafts and retaining walls in below-grade waterproofing systems
- Lining of ornamental ponds, lagoons and water features
- Reservoir and water-retaining structure lining where a flexible barrier is needed
- Green roof and roof garden assemblies, using the root-resistant membrane grade
- Podium decks and terraces receiving protection screed and finishes
- Waterproofing of sports facilities and landscaped recreational structures
- Refurbishment of failed felt roofs after removal or preparation of the old system
Key advantages
- Exceptional resistance to UV, ozone and weathering — suitable for fully exposed roofs without a protective coat
- Elongation above 300% (ASTM D412) accommodates structural movement and crack bridging
- Stays flexible at −45°C, so thermal cycling does not embrittle or fatigue the sheet
- Single-ply installation: one factory-made layer instead of multiple site-built plies, with fewer things to go wrong
- Cold-applied jointing with adhesive or splice tape — no torching, no hot bitumen, safer on occupied buildings
- Service life expectancy of 30–50 years when substrate and seams are executed correctly
- Non-toxic membrane suited to ponds and water features
- Lightweight sheet adds negligible dead load, useful on refurbishment of older structures
Limitations & considerations
- Performance is seam-dependent: field joints made with adhesive or tape are the weakest link and demand trained applicators and joint-by-joint inspection
- EPDM swells and degrades in contact with oils, greases, solvents and fresh bitumen — keep it away from hydrocarbon spillage and uncured bituminous layers
- The black sheet absorbs solar heat; on exposed Indian terraces consider ballast, shading or overburden where roof surface temperature is a concern
- Not a trafficable finish — podiums, terraces in use and car decks need a protection layer and screed over the membrane
- Sharp protrusions and rough substrates can puncture the sheet, so surface regularisation and protection from follow-on trades are non-negotiable
- Higher initial material cost than APP/bituminous felt, recovered only over the longer service life
Selection & best practice
Start with the substrate: it must be smooth, dry, cured and free of sharp fins, aggregate nibs and laitance — grind or fill irregularities rather than hoping the sheet spans them. Plan the sheet layout to push seams away from drains, upstands and gutters, and unroll the membrane and let it relax before bonding to release packing tension. Join sheets with contact adhesive or self-adhesive EPDM splice tape over a cleaned, primed overlap, and roller-press every seam; for below-grade work use vulcanisation tape as recommended by STP. Probe-test each field joint before handover. Carry the membrane at least 150 mm up parapets and terminate mechanically with a sealed termination bar. Below grade or under screeds, cover the membrane with a protection board the same day. Confirm details against the current STP Limited TDS and method statement before starting.
Specifications
| Material | EPDM synthetic rubber, single-ply preformed sheet, black |
| Classification | Conforms to ASTM D4637 Type I |
| Tensile strength | > 9 MPa (ASTM D412) |
| Elongation at break | > 300% (ASTM D412) |
| Low-temperature flexibility | Passes at −45°C |
| Available thicknesses | 1.0 mm, 1.2 mm, 1.5 mm |
| Service life expectancy | 30–50 years (system dependent) |
| Seam jointing | Contact adhesive or self-adhesive EPDM splice tape; vulcanisation tape for below-grade |
Industry use cases
Commercial & IT Buildings
Exposed single-ply roofing over office blocks and data facilities where a no-flame, low-maintenance roof with a multi-decade life justifies the premium over felt.
Industrial Plants & Warehousing
Large-format roof waterproofing where long uninterrupted sheet runs cut seam count, and cold application avoids hot works permits over operating floors.
Residential & Group Housing
Terrace and podium waterproofing under screed and finishes, plus basement retaining walls in NCR’s high-water-table pockets.
Water & Landscape Infrastructure
Lining of reservoirs, lagoons, ornamental ponds and water bodies where a flexible, non-toxic, ozone-proof barrier must last outdoors.
Institutional & Sports Facilities
Green roofs, landscaped decks and sports building waterproofing using the root-resistant grade beneath planting and overburden.
Frequently asked questions
How is ShaliEPDM different from an APP or SBS bituminous membrane?
Which thickness should I specify — 1.0, 1.2 or 1.5 mm?
How are the sheets joined on site — is any torching involved?
Can ShaliEPDM be laid over an old bituminous felt roof?
Is it safe for ponds and water features with plants or fish?
Does Space Arc supply only, or also arrange application?
How we position STP ShaliEPDM
ShaliEPDM sits at the premium end of STP Limited’s waterproofing range: where budgets are tighter or a torch-applied system is preferred, STP’s SuperThermoLay APP membranes remain the workhorse choice, while STP’s liquid-applied ShaliUrethane polyurethane systems suit detail-heavy terraces with many penetrations where sheet jointing becomes tedious. For new basements cast against the waterproofing, many consultants specify a pre-applied system instead — see Fosroc Proofex Engage in our range. Space Arc also supplies Sika and Dr. Fixit membrane and liquid systems, so we can price the same roof or basement across brands and let the specification decide.
Fosroc Proofex Engage — For new-build basements, specifiers often prefer pre-applied Proofex Engage because its cell mesh locks into the fresh concrete and stops lateral water migration — choose ShaliEPDM where the membrane serves roof, liner or post-applied duties.
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