Sika Sarnafil S 327-15 L
A 1.5 mm polyester-reinforced PVC single-ply membrane engineered for mechanically fastened, fully exposed roofs on large-span commercial and industrial buildings.
What is it?
A 1.5 mm thick, polyester-reinforced flexible PVC (PVC-P) waterproofing membrane supplied in rolls, with a reflective white top surface and dark-grey underside, conforming to EN 13956.
Where is it used?
Exposed flat and low-slope roofs on warehouses, factories, logistics parks, retail sheds, airports and coastal industrial structures where a lightweight, mechanically fixed system is preferred over ballast or adhesion.
Why use it?
It gives a fast, hot-air weldable, fully bonded seam system with high wind-uplift resistance, a solar-reflective surface for lower roof temperatures, and long exposed service life without a protective screed.
How is it applied?
Rolled out over the insulation/deck, mechanically fastened at the laps with Sarnabar or Sarnafast fixings, then hot-air welded along overlaps at minimum +600 C to form continuous, homogeneous seams.
About Sika Sarnafil S 327-15 L
Sarnafil S 327-15 L belongs to Sika’s single-ply thermoplastic roofing family, a category that has quietly replaced built-up felt and bituminous systems on most large exposed roofs. Instead of layering hot bitumen and torching overlaps, the installer unrolls a factory-made sheet and welds the joints with hot air. The result is a lightweight, monolithic waterproofing skin whose seams are as strong as the membrane itself. The “15” in the name denotes the 1.5 mm nominal thickness, and the “L” grade is the loose-laid, mechanically fastened variant intended for direct weather exposure rather than adhered or ballasted build-ups.
For Indian projects, the appeal is practical. The membrane is polyester-scrim reinforced, so it carries the tensile load imposed by wind suction without stretching or tearing at the fastener line, which matters on the open, high-wind roofs common to industrial estates and coastal belts. The white matt top surface reflects a large share of incident solar radiation, helping keep the roof deck and the space below cooler, a genuine benefit under Indian summer loads. As an authorised distributor, Space Arc supplies the membrane together with the compatible Sarnabar and Sarnafast fixing components and can connect specifiers with trained applicators across Delhi NCR and Pan-India.
The technical insight
The performance of this system rests on two things working together: the reinforcement and the weld. The flexible PVC compound gives the sheet its waterproofing and weathering ability, but on its own PVC-P would creep and elongate under sustained wind uplift. The embedded polyester scrim carries that tension, which is why the sheet is rated at a tensile strength of at least 1000 N per 50 mm in both directions and shows very limited elongation before the reinforcement takes the load. That combination lets the membrane sit loose over the deck, restrained only at the fastener lines, and still resist the peeling forces generated when wind lifts the sheet. The second half of the mechanism is thermoplastic welding. Because PVC softens and re-fuses with heat, hot air at 600 C or above melts the overlapping edges into a single continuous material rather than gluing two separate sheets. A correctly executed weld is therefore not a joint that can debond over time; it is a homogenous section of membrane. The reflective white surface adds a durability dimension too, holding an initial solar reflectance around 0.84 that lowers the membrane’s operating temperature and slows the thermal ageing that eventually embrittles darker roofing.
Where it is used
- Mechanically fastened, exposed waterproofing on large-span warehouse and factory roofs
- Logistics parks, distribution centres and cold-store buildings needing lightweight cover
- Retail sheds, malls and big-box structures where fast roof enclosure is required
- Coastal and high-wind industrial roofs demanding proven uplift resistance
- Cool-roof upgrades where a reflective white surface reduces heat gain
- Re-roofing and renovation over existing decks without heavy ballast loads
- Roofs on lightweight steel-deck structures with limited load capacity
- Institutional and infrastructure buildings such as terminals and hangars
Key advantages
- Polyester reinforcement delivers high tensile strength (>=1000 N/50 mm) and strong wind-uplift resistance
- Hot-air welded seams fuse into a homogeneous, fully watertight joint
- Reflective white top surface (approx 0.84 solar reflectance) lowers roof and interior temperatures
- Lightweight system suits steel decks and re-roofing without added structural load
- Fast, screed-free installation shortens the roof enclosure programme
- Watertight to EN 1928 and classified for external fire exposure (BROOF t1)
- Durable UV-stabilised PVC formulated for permanent direct exposure
- Backed by the Sarnabar/Sarnafast fixing range for a complete engineered system
Limitations & considerations
- It is a mechanically fastened, exposed system, not intended for adhered, ballasted or buried tanking use
- PVC membranes are not chemically compatible with bitumen or polystyrene insulation without a separation layer
- Hot-air welding demands trained applicators and calibrated equipment; poor welds compromise watertightness
- Not designed for permanently ponded or immersed conditions such as deep basements or water tanks
- Penetrations, upstands and detailing require care and correct accessories to remain leak-free
- Roll handling and welding are weather-sensitive; cold, wet or very windy conditions affect quality
Selection & best practice
Confirm the deck and insulation are dry, sound and compatible before laying, using a separation fleece wherever the PVC could contact bitumen or polystyrene. Set out fastener rows to the wind-load calculation for the specific roof zone, tightening perimeter and corner fixing where uplift is highest. Overlap adjacent rolls to the specified width and hot-air weld the laps at a minimum of 600 C, checking seam integrity along the full length with a seam probe once cooled. Detail all upstands, drains and penetrations with the matching Sika accessories rather than site-formed joints. Store rolls upright, dry and shaded until installation, and schedule welding for stable, dry conditions to protect weld quality. Always work to the current Sika method statement for the chosen fixing system.
Specifications
| Product type | Polyester-reinforced flexible PVC (PVC-P) single-ply roofing membrane |
| Standard | EN 13956 (polymeric sheets for roof waterproofing) |
| Nominal thickness | 1.5 mm |
| Roll size | 2.0 m wide x 20.0 m long (approx. 40 m2 per roll) |
| Roll weight | Approx. 78 kg |
| Colour | White matt top surface / dark-grey underside |
| Tensile strength | >=1000 N/50 mm (longitudinal and transversal) |
| Solar reflectance (white) | Approx. 0.84 initial (approx. 0.70 after 3-year ageing) |
| Watertightness | Pass to EN 1928 |
| Fire performance | Reaction to fire Euroclass E; external fire BROOF (t1) |
| Service temperature | -20 C to +60 C ambient application range |
| Installation | Mechanically fastened; hot-air welded seams at min. +600 C |
Industry use cases
Warehousing & Logistics
Large steel-deck roofs enclosed quickly with a lightweight, mechanically fixed reflective membrane that keeps stored goods cooler.
Manufacturing & Industrial
Factory and plant roofs where high wind-uplift resistance and a screed-free, fast-track system reduce downtime during construction.
Retail & Commercial
Malls, big-box stores and showrooms needing a durable, low-maintenance exposed roof with a cool white surface.
Coastal & High-Wind Sites
Buildings in coastal or exposed belts where the polyester-reinforced sheet resists peeling and uplift at the fastener lines.
Re-roofing & Renovation
Refurbishment over existing decks where added ballast weight is not viable and a light single-ply overlay is preferred.
Frequently asked questions
What does ‘S 327-15 L’ actually mean?
Is it adhered or mechanically fixed?
Can it be used on basements or water tanks?
Why is the top surface white?
Do the seams need special equipment?
What roll size and coverage should I plan for?
How we position Sika Sarnafil S 327-15 L
Sarnafil S 327-15 L sits at the exposed, mechanically fastened end of Sika’s single-ply roofing range. Where a project needs an adhered or ballasted PVC build-up, or a thicker sheet for a longer design life, other Sarnafil S 327 thickness grades and adhered variants are the natural step up within the same family, paired with Sika’s Sarnabar and Sarnafast fixing accessories to complete the system. For applications this membrane is not meant for, Space Arc can offer alternatives from our other brands: liquid-applied and cementitious roof waterproofing from Dr. Fixit and Fosroc for smaller or heavily detailed roofs, and torch-applied bituminous membranes where a built-up exposed system or below-grade tanking is specified rather than thermoplastic single-ply.
Fosroc Proofex Torchseal 3P & 4P — A specifier may prefer this torch-applied APP-modified bitumen membrane when the roof calls for a traditional built-up exposed system, or when the same detail extends into below-grade tanking where single-ply PVC is unsuitable.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.