About Sika SikaShield P35 MG IN 4 mm

SikaShield P35 MG IN 4 mm sits in the exposed-membrane end of Sika’s torch-on range. It is a prefabricated bituminous sheet, 4 mm thick, in which APP (atactic polypropylene) modified bitumen is calendered around a non-woven polyester carrier. The top surface carries mineral granules and the underside a thermofusible burn-off film, so the same roll both protects itself against sunlight and bonds cleanly under a torch flame. For engineers, the shorthand is simple: it is the single-ply or cap-layer sheet you specify when the waterproofing is going to stay visible and take weather, not disappear under tiles or a topping.\n\nThe product was previously catalogued as SikaBit T-140 MG IN, so older tender documents and BOQs may still carry that name for the same sheet. Supplied in rolls of 1.0 m by 10.0 m, it is engineered around Indian site conditions where roofs bake through summer and then flood in the monsoon. As an authorised Sika distributor and applicator across Delhi NCR and Pan-India, Space Arc supplies the membrane alongside the compatible primers and detailing accessories that make the system perform as tested, rather than as loose rolls.

The technical insight

The performance of this membrane comes from a deliberate division of labour between its three layers. The non-woven polyester carrier is the structural spine: it gives longitudinal tensile strength of 600 N/50 mm and around 45% elongation, so the sheet can stretch over hairline shrinkage cracks and accommodate thermal cycling without splitting, while its +260 C melting point means it survives the torch flame during installation. The APP-modified bitumen is the waterproofing body and the thermoplastic glue; APP raises the softening point above 150 C, which is what stops the membrane creeping or flowing on a hot exposed roof where surface temperatures climb well beyond ambient. The mineral granules on top are the sacrificial UV shield, reflecting and absorbing radiation that would otherwise oxidise and embrittle the bitumen over time. Because the sheet is factory-made to a controlled 4 mm thickness, the waterproofing barrier is uniform across the whole roof, which is exactly what liquid-applied systems struggle to guarantee at internal corners and around penetrations.

Where it is used

• Permanently exposed flat and sloping roofs up to a 15% gradient
• Terraces and balconies where the membrane stays visible and trafficked
• Podium decks and horizontal RCC slabs above occupied space
• Bridge decks beneath an asphalt wearing course
• Cap (top) layer over a base membrane in two-ply exposed roofing systems
• Single-layer waterproofing on parapets, upstands and protrusions
• Refurbishment overlays on sound existing bituminous roofing
• Decks and podiums requiring a UV-stable finished surface

Key advantages

• Mineral-granule top face gives permanent UV resistance without a separate protective screed
• Non-woven polyester core delivers high tensile strength (600 N/50 mm MD) and roughly 45% elongation to bridge cracks
• APP modification pushes the softening point above 150 C, resisting flow and sag on hot exposed roofs
• Factory-controlled 4 mm thickness ensures a uniform barrier across the whole area
• Fully torch-bonded to eliminate the water tracking that plagues loose-laid systems
• Watertight to a head of at least 60 kPa, comfortably handling monsoon ponding
• Fast to lay in large rolls, keeping labour and programme time down on big decks
• Backed by Space Arc supply and applicator support across Delhi NCR and Pan-India

Limitations & considerations

• Requires an open torch flame, so it is unsuitable near flammable materials, stored goods or occupied interiors without hot-work controls
• Application is limited to substrate and ambient temperatures between +5 C and +40 C, ruling out very cold mornings and peak-summer afternoons
• The substrate must be dry with moisture below 6%, which needs adequate curing and drying time before work starts
• Flexibility is rated only to around -5 C, so it is not the first choice for genuinely sub-zero cold-store or high-altitude exposure
• Quality depends heavily on the applicator getting torch heat and lap fusion right; poor workmanship shows up as failed seams
• As a mineral-finished cap sheet it is not intended for buried or below-grade tanking, where a plain-film membrane is more appropriate

Selection & best practice

Specifications

Industry use cases

How we position Sika SikaShield P35 MG IN 4 mm

Within the Sika family, pair this cap sheet with a compatible SikaShield base membrane for two-ply exposed systems, and use a Sika bituminous primer for adhesion; where a plain-film or self-adhesive variant suits a buried detail, the wider SikaShield range covers those cases. For projects that call for a liquid-applied alternative around complex penetrations, Sika’s polyurethane and cementitious waterproofing lines are the natural companions. Across our other brands, comparable torch-on membranes are available from Dr. Fixit and STP, while cementitious tanking systems from Fosroc and MC-Bauchemie serve below-grade work that a mineral-finished cap sheet is not designed for.

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