Sika SikaShield P35 MG IN 3 mm
A 3 mm APP-modified bituminous membrane with a non-woven polyester core and mineral-granule cap, torch-bonded for exposed roofs, podiums and bridge decks.
What is it?
A 3 mm prefabricated waterproofing membrane made from APP-modified bitumen reinforced with a non-woven polyester carrier, finished with a mineral-granule top surface and a burn-off film on the underside.
Where is it used?
Exposed flat and sloping roofs up to 15% gradient, terraces, balconies, podium decks over occupied or parking areas, and bridge decks beneath an asphalt wearing course.
Why use it?
It delivers a fully-bonded, seam-welded barrier that stays flexible down to -5 C, resists UV without a separate screed, and carries ISO-referenced test values engineers can specify against.
How is it applied?
Torch-fused to a primed, dry substrate (moisture below 6%) with 80-100 mm side laps and 150 mm end laps, working at ambient and substrate temperatures between +5 C and +40 C.
About Sika SikaShield P35 MG IN 3 mm
SikaShield P35 MG IN 3 mm is a factory-made bituminous sheet membrane engineered for horizontal and low-slope waterproofing where the finished surface is left exposed. The core is a non-woven polyester carrier coated on both faces with atactic-polypropylene (APP) modified bitumen. This combination gives the roll two things a specifier cares about at once: the polyester provides tensile strength and dimensional stability, while the APP compound raises the softening point and holds the membrane together across the temperature swings of an Indian rooftop. The top face is finished with grey mineral granules that shield the bitumen from ultraviolet degradation, and the underside carries a thermofusible burn-off film that indicates correct torching temperature during installation.
In practice this is a cap-sheet-grade membrane. It can be laid as a single self-finished layer on accessible roofs and terraces, or used as the exposed top ply in a two-layer build-up over a plain reinforced base sheet. Because the granular surface is UV-facing and paintable, it suits projects where the waterproofing doubles as the wearing surface rather than being buried under protective concrete. Space Arc supplies and applies SikaShield P35 MG across Delhi NCR and pan-India, and the membrane sits within Sika’s wider SikaShield torch-applied range so base sheets, primers and detailing accessories come from one compatible system.
The technical insight
The performance of this membrane comes from pairing two materials that compensate for each other’s weaknesses. Straight oxidised bitumen is watertight but brittle in the cold and prone to flow when hot; APP modification widens that usable window, pushing the softening point to at least 150 C (ASTM D36) while keeping the sheet flexible down to -5 C (EN 1109). The non-woven polyester carrier then does the structural work — it is what delivers the 600 N/50mm longitudinal tensile strength and the roughly 45% elongation, letting the sheet accommodate substrate movement, thermal cycling and minor cracking without tearing. During installation the torch flame melts the burn-off film and the underside compound simultaneously, so the membrane wets out and fuses directly to the primed deck; the same heat welds the overlaps into continuous, homogeneous seams rather than mechanical joints. The result behaves as one monolithic sheet under a 60 kPa water head (EN 1928), which is why torch-applied laps, when properly heated, are the most reliable detail on the roll.
Where it is used
- Exposed waterproofing on flat and sloping roofs up to a 15% gradient
- Terraces and balconies in residential and hospitality buildings where the membrane is the finished surface
- Podium slabs and decks over occupied floors, basements or parking areas
- Bridge decks and viaducts beneath an asphalt wearing course
- Cap-sheet (top ply) in a two-layer torch-applied system over a plain base sheet
- Waterproofing of horizontal RC slabs, upstands and protrusions
- Refurbishment overlays on sound existing bituminous roofing
Key advantages
- Mineral-granule top face resists UV, so the membrane can stay permanently exposed without a protective screed
- APP modification holds a softening point of 150 C or higher, resisting summer flow on Indian rooftops
- Stays flexible to -5 C, reducing the risk of cold cracking at laps and upstands
- Non-woven polyester core gives high tensile strength (600 N/50mm MD) and good elongation for movement accommodation
- Torch-welded overlaps form continuous monolithic seams rather than weaker mechanical joints
- Burn-off indicator film on the underside helps applicators judge correct torching temperature
- Supplied with ISO/EN and ASTM referenced test data, making it straightforward to specify and approve
- Part of the wider SikaShield system, so base sheets, primers and detailing accessories are fully compatible
Limitations & considerations
- Requires open-flame torching by trained applicators, which restricts use near flammable substrates, insulation or occupied fit-outs
- Substrate must be dry with moisture below 6% and properly primed, so wet-season or green-concrete work needs planning
- Application window is limited to substrate and ambient temperatures of +5 C to +40 C
- At 3 mm it is generally a cap-sheet or single-layer solution; heavy-duty tanking or aggressive groundwater may call for a thicker 4 mm sheet or a two-ply build-up
- As a torch-down bituminous system it is less suited to intricate detailing than a liquid-applied membrane on complex geometry
- Twelve-month shelf life means rolls should be stored upright, dry and rotated, not stockpiled long term
Selection & best practice
Start with a clean, sound and dry substrate — laitance and dust removed, moisture below 6% — and prime the deck with a compatible bituminous primer, letting it dry fully before torching. Align rolls to shed water with the fall and dry-lay them first to set out laps: 80-100 mm on the sides and 150 mm at the ends, staggering end joints so four layers never coincide. Heat the underside burn-off film and the substrate together until the film melts and a small bead of molten bitumen appears at the leading edge, then roll the membrane forward into it, pressing out air. Seal every overlap by re-heating and troweling the seam until a continuous bitumen line is visible along the edge — this bead is the proof of a welded joint. Reinforce internal corners, drains and upstands with cut patches, and avoid overheating, which scorches the compound and burns off the polyester’s benefit. Work within the +5 C to +40 C window and flood-test critical areas before any overlay or ballast goes down.
Specifications
| Product type | APP modified bituminous membrane, non-woven polyester reinforced |
| Thickness | 3 mm (+0.3 / -0.2 mm, EN 1849-1) |
| Roll dimensions | 1.0 m wide x 10.0 m long (10 m per roll) |
| Cold flexibility | less than or equal to -5 C (EN 1109) |
| Softening point | greater than or equal to 150 C (ASTM D36) |
| Watertightness | greater than or equal to 60 kPa (EN 1928, Method B, 24 h) |
| Tensile strength (MD / CMD) | 600 +/- 120 N/50mm / 450 +/- 90 N/50mm |
| Elongation | 45 +/- 15% (both directions) |
| Top / underside finish | Grey mineral granules / thermofusible burn-off film |
Industry use cases
Commercial and residential roofing
Exposed cap-sheet waterproofing on flat and sloped roofs up to 15% gradient, where the granular surface serves as the finished, UV-facing layer.
Infrastructure and bridges
Deck waterproofing on viaducts and bridge slabs, laid beneath the asphalt wearing course to protect the structural concrete.
Podiums and car parks
Membrane barrier over podium decks and parking slabs above occupied or basement areas, tolerating traffic loads once the protection layer is in place.
Hospitality and residential terraces
Waterproofing of accessible terraces and balconies in hotels and apartments where a durable, self-finished exposed surface is required.
Refurbishment
Overlay waterproofing on sound existing bituminous roofs, restoring watertightness without full tear-off.
Frequently asked questions
Can SikaShield P35 MG IN 3 mm be left exposed to sunlight?
Is 3 mm enough, or should I use the 4 mm version?
How is it fixed to the substrate?
What lap widths should the applicator use?
What substrate condition is required before laying?
How should the rolls be stored?
How we position Sika SikaShield P35 MG IN 3 mm
SikaShield P35 MG IN 3 mm is the exposed, mineral-finished cap sheet in Sika’s torch-applied bituminous range; pair it with a plain SikaShield base sheet and a bituminous primer for a full two-layer roof system, or step up to the 4 mm grade for heavier tanking duty. Where a project calls for a seamless, detail-friendly alternative on complex geometry, our Sika liquid-applied polyurethane and cementitious membranes are the natural cross-reference. Among our other brands, Dr. Fixit and STP also offer APP torch-down membranes for value-led jobs, while Fosroc’s Proofex Torchseal is a like-for-like specification option.
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