Sika SikaShield P24 MG IN 4 mm
A 4 mm APP-modified bituminous membrane with a mineral-granule top surface, torch-bonded for exposed roofs, terraces and podium decks that face constant sun and foot traffic.
What is it?
A 4 mm thick, APP-modified bituminous waterproofing membrane reinforced with a non-woven polyester fabric, finished with mineral granules on top and a burn-off PE film underneath.
Where is it used?
Exposed flat and low-slope roofs up to 15% gradient, terraces, balconies, podium decks, horizontal RCC slabs and bridge decks beneath an asphalt wearing course.
Why use it?
It handles permanent UV exposure without a separate protective screed, stays flexible down to -2 C, and gives a fully bonded, decorative single-layer or cap-sheet finish.
How is it applied?
Torch-applied over a primed, dry substrate: the underside PE film is melted with a gas burner and the sheet is rolled and pressed down, with welded 80-100 mm side and 150 mm end overlaps.
About Sika SikaShield P24 MG IN 4 mm
SikaShield P24 MG IN 4 mm is Sika’s mineral-surfaced, torch-on waterproofing membrane, formerly sold in India as Sika WP Shield-104 PM. It is built around a non-woven polyester core that is coated on both faces with Atactic Poly Propylene (APP) modified bitumen. The APP modification is what lets the sheet stay serviceable across the wide temperature swings an Indian rooftop sees through the year, while the polyester reinforcement carries the tensile, tear and dimensional loads. At 4 mm it sits at the heavier end of the exposed-membrane range, which is the thickness most specifiers reach for when a roof has to work as a single exposed layer or as the visible cap sheet in a two-ply build-up.
The defining feature is the grey mineral-granule top surface. Those granules shield the bitumen from ultraviolet light, so the membrane can be left permanently exposed without an over-screed or a separate UV coat, and they give the finished roof a durable, walkable, decorative face. The black polyethylene film on the underside burns off cleanly under the torch flame to create a fully bonded, continuous bond to the deck. For Delhi NCR and Pan-India projects, Space Arc Engineering supplies the membrane as an authorised Sika distributor and applicator, so contractors get both the genuine product and site-level guidance on primer selection, detailing and torching.
The technical insight
The performance of this membrane comes from pairing an APP-modified bitumen compound with a non-woven polyester carrier. APP is a thermoplastic polymer blended into the bitumen; it raises the softening point to at least 145 C (ASTM D36) and gives “no flow at +120 C for 2 hours”, meaning the compound will not sag or run on a hot exposed roof in peak summer. At the other end, the formulation stays flexible down to -2 C (EN 1109), so the sheet resists cracking during cold-weather handling and thermal contraction. The polyester reinforcement is the structural heart: it delivers longitudinal tensile strength of 600 plus or minus 150 N/50 mm and around 40% elongation, letting the membrane bridge minor substrate movement and shrinkage cracks rather than tearing over them. During installation the burn-off PE film on the underside acts as a heat indicator; once it melts and forms a bead of molten bitumen, the operator knows the compound is activated and the sheet will fuse to both the substrate and adjacent overlaps as a monolithic, watertight skin rated to 10 kPa (EN 1928).
Where it is used
- Exposed waterproofing to flat and low-slope RCC roofs with gradients up to 15%
- Terrace and balcony waterproofing where a walkable, UV-stable finish is needed
- Podium decks and horizontal reinforced-concrete slabs
- Bridge decks beneath an asphalt wearing layer
- Cap sheet (top layer) in a two-ply torch-applied roofing system
- Single-layer exposed waterproofing on demanding commercial and institutional roofs
- Protrusions, upstands and roof details in conjunction with the main sheet
- Roofs where tiles are to be laid directly over the membrane
Key advantages
- Mineral-granule surface withstands permanent UV exposure, so no separate protective screed is required
- Fully bonded torch application eliminates lateral water tracking under the membrane
- Stays flexible to -2 C yet holds shape with no flow up to +120 C for 2 hours
- High tensile and tear strength from the non-woven polyester reinforcement for good crack bridging
- Decorative grey finish that can be painted immediately or receive tiles directly
- Low water absorption and proven watertightness at 10 kPa
- Good long-term ageing and durability under thermal and structural stress
- Handles easily in warm site temperatures and installs by a single torching operation
Limitations & considerations
- Requires open-flame torching, so a trained applicator and fire-safety precautions are essential on site
- The polyester reinforcement melts at +260 C and is ruined by overheating, so flame control and moving the torch are critical
- Substrate moisture must be below 6% and ambient/substrate temperature between +10 C and +40 C, which limits monsoon and cold-weather work
- As a rolled sheet it suits large plane areas; heavily congested roofs with many penetrations need extensive hand-detailing
- Insufficient heating gives weak adhesion at overlaps and to the deck, a common cause of leaks if workmanship is poor
- Not a self-levelling liquid system, so it cannot follow complex or intricate geometries as easily as a coating
Selection & best practice
Cure new concrete for at least 28 days and confirm a pull-off strength of 1.5 N/mm2 or better; the surface must be firm, smooth, dry (moisture under 6%) and free of laitance, oil, dust and sharp protrusions. Prepare mineral substrates mechanically, then apply the correct SikaShield primer and let it dry fully before laying. Work only when ambient and substrate temperatures are between +10 C and +40 C. Align and re-roll each sheet, then torch the underside PE film and substrate together, rolling the membrane forward and pressing firmly until a bead of molten bitumen shows along every side and end overlap; keep the flame moving to avoid scorching the polyester. Lap 80-100 mm on the sides and 150 mm on the ends, cut a 45-degree corner at end laps, and stagger joints so they never coincide, especially over a previous membrane layer. Use a sharp knife to detail corners, upstands, vent pipes and drains, and walk the finished roof only in flat-profile footwear.
Specifications
| Chemical base | APP-modified bitumen on non-woven polyester fabric |
| Thickness | 4 mm (+0.3 / -0.2 mm), EN 1849-1 |
| Roll size | 1.0 m wide x 10.0 m long (EN 1848-1) |
| Top / bottom surface | Grey mineral granules / black burn-off polyethylene film |
| Softening point | ≥ 145 C (ASTM D36); no flow at +120 C for 2 h (EN 1110) |
| Flexibility at low temperature | ≤ -2 C (EN 1109) |
| Tensile strength | 600 ± 150 N/50 mm longitudinal; 400 ± 150 N/50 mm transversal (EN 12311-1) |
| Elongation | 40 ± 10% both directions (EN 12311-1) |
| Watertightness | ≥ 10 kPa (Method B, 24 h, EN 1928) |
Industry use cases
Commercial and institutional roofing
Exposed single-layer or cap-sheet waterproofing on large flat RCC roofs where a UV-stable, walkable finish avoids the cost and dead-load of a protective screed.
Residential terraces and balconies
Torch-bonded membrane for terraces and balconies that gives a durable grey finish able to take direct tiling or immediate painting.
Infrastructure and bridges
Deck waterproofing beneath an asphalt wearing course, using the high tensile and tear strength to survive traffic and thermal stress.
Podiums and elevated decks
Waterproofing to podium slabs and elevated horizontal decks where crack-bridging and full adhesion prevent water tracking into occupied spaces below.
Two-ply built-up roofing
Serves as the exposed mineral cap sheet over a plain base membrane on demanding roofs that need redundancy against ageing and mechanical damage.
Frequently asked questions
Can SikaShield P24 MG IN 4 mm be left permanently exposed, or does it need a protective screed?
What is the difference between the 3 mm and 4 mm versions?
What roof slope does it suit?
How is it installed and does it need a primer?
What substrate and weather conditions are required?
Does Space Arc supply genuine Sika membrane and offer application support?
How we position Sika SikaShield P24 MG IN 4 mm
Within the Sika range, this 4 mm mineral-finished sheet is the exposed, decorative option; pair it with a plain SikaShield base membrane for a robust two-ply build-up, and always specify the matching SikaShield primer for the deck. Where a project calls for a thinner cap or intermediate layer, the SikaShield P24 MG IN 3 mm variant covers the same duty at lower mass. For roofs where an open-flame torch is not permitted or the geometry is too intricate for sheets, Space Arc can offer a liquid-applied alternative such as Fosroc Nitoproof 800 polyurethane, and for cementitious tanking situations a brush-applied coating is a better fit than any torch membrane.
Fosroc Proofex Torchseal 4PI — A specifier standardising a project on the Fosroc waterproofing system would choose this directly equivalent 4 mm APP polyester-reinforced torch-on membrane instead.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.