Sika SikaProof-315 HDPE SG W IN
Pre-applied, fully bonded HDPE membrane that grips fresh concrete and blocks lateral water tracking under rafts and blindside walls.
What is it?
A pre-applied, fully bonded below-ground waterproofing membrane built from a virgin HDPE film, a pressure-sensitive adhesive layer and a sand-sprinkled protective coat.
Where is it used?
Blindside basement walls, raft foundations, lift pits, tunnels, subways and other below-ground concrete cast against or over the membrane.
Why use it?
The adhesive bonds integrally to the fresh concrete, so even if the structure is later breached, water cannot migrate through the interface to a distant point.
How is it applied?
Loose-laid over blinding or shutter face with the sand side up, laps sealed at 80 mm, reinforcement fixed directly on top, then concrete poured within 45 days.
About Sika SikaProof-315 HDPE SG W IN
SikaProof-315 HDPE SG W IN belongs to Sika’s family of pre-applied, fully bonded sheet membranes designed for structures where you simply cannot get to the outer face once the concrete is in. Think deep basements poured against secant piles, cut-and-cover metro boxes, lift pits and raft slabs sitting on blinding. The membrane is rolled out before the reinforcement goes down, so the concrete is cast directly against it. As the pour cures, the pressure-sensitive adhesive keys into the cement paste and forms a continuous, integral bond to the finished structure rather than a loose contact layer.
That integral bond is the whole point. With a loose-laid sheet, a puncture anywhere lets ground water travel unseen between membrane and concrete until it finds a construction joint or crack, and tracing the leak becomes guesswork. Because SikaProof-315 is locked to the concrete face, any water ingress stays local to the point of damage instead of migrating across the slab. For engineers designing Type A (barrier) protection to IS 16471 on high water tables across Delhi NCR and coastal projects, that predictability is what makes a pre-applied bonded system worth specifying over conventional self-adhesive bitumen sheets.
The technical insight
The membrane is a three-part composite: a tough virgin HDPE carrier film that carries the mechanical load, a pressure-sensitive adhesive that does the bonding, and an inorganic sand-sprinkled layer that both protects the adhesive during site traffic and gives the fresh concrete something to grip. When concrete is poured, cement fines work into the sanded adhesive surface and, on hydration, the adhesive cross-links physically into the paste. The result is a bond measured above 1500 N/m in peel at seven days, strong enough that water cannot shear the interface apart under head. The HDPE film contributes the strength and durability: tensile strength of at least 25 MPa with elongation over 500% lets it accommodate settlement and minor crack movement, while roughly 1200 N of static puncture resistance survives rebar chairs and foot traffic during the reinforcement stage. Watertightness is verified to a hydrostatic head above 71 m, so the system is not the limiting factor even on the deepest basements. Field joints rely on the same HDPE chemistry: overlaps of 80 mm are hot-air welded through the selvedge to give a homogeneous, self-healing seam rather than a taped mechanical lap.
Where it is used
- Blindside basement walls cast against secant pile, diaphragm or contiguous bored pile walls
- Raft foundations and ground-bearing slabs laid over blinding concrete
- Lift pits, escalator pits and other deep sumps below the water table
- Metro stations, subways and cut-and-cover tunnel boxes
- Underground car parks and multi-level basements in high-groundwater zones
- Water-retaining and water-excluding tanks below ground
- Podium and transfer slabs where re-access to the outer face is impossible
- Premium residential basements requiring long-term dry, habitable space
Key advantages
- Integral bond to the poured concrete confines any leak to the point of damage, making leaks traceable and locally repairable
- Pre-applied method removes the need for external access, protection screeds or blinding-side working room
- Reinforcement can be fixed and tied directly on the membrane, keeping the sequence fast
- Virgin HDPE film gives high puncture and tensile strength to survive the rebar and pour stage
- Chlorine-, plasticizer- and phthalate-free composition with no bitumen bleed or odour
- Hot-air welded HDPE laps give homogeneous, durable seams instead of adhesive-only overlaps
- Watertight to over 71 m hydrostatic head, covering the deepest practical basements
- Complies with IS 16471:2017 for bonded sheet membranes, easing consultant approval on Indian projects
Limitations & considerations
- Concrete must be cast within 45 days of installation, so the membrane cannot sit exposed indefinitely before the pour
- Application and substrate must stay within +5 C to +40 C; below +5 C needs special precautions
- Prolonged UV exposure degrades performance, so it is not a finished exposed surface
- Hot-air welding of laps needs trained operators and correct temperature and speed settings to guarantee seam integrity
- Substrate must be sound, reasonably even and free of standing water, sharp protrusions and debris before laying
- As a Type A barrier system it should be detailed with attention to penetrations and construction joints; it is not a substitute for good waterstop design
Selection & best practice
Lay the membrane sand-side up onto a clean, firm blinding or shutter face, keeping it as taut and flat as practical. Seal side laps by overlapping the selvedge 80 mm and hot-air welding within the +275 C to +375 C band at 0.8 to 2 m/min; at transverse joints, remove the sand layer over the overlap and seal with the matching SikaProof tape. Protect the adhesive from rain, dust and prolonged sun until the pour, and cover any exposed edges. Fix reinforcement directly on the membrane using spacers that will not puncture it, and pour concrete within the 45-day window so the adhesive is still fully active. Always use a Sika-trained or approved applicator, dry-lay and check the sequence at penetrations, pipe boxes and pile heads first, and store rolls horizontally between +5 C and +35 C in the original PE-foil until use.
Specifications
| Membrane type | Pre-applied, fully bonded HDPE sheet membrane (virgin HDPE + adhesive + sand topping) |
| Effective thickness | >= 1.8 mm composite |
| Tensile strength | >= 25 MPa (ASTM D412 mod.) |
| Elongation at break | > 500% (ASTM D412 mod.) |
| Static puncture resistance | 1200 N +/-10% (ASTM E154) |
| Peel adhesion to concrete | > 1500 N/m at 7 days (ASTM D903 mod.) |
| Watertightness | > 71 m hydrostatic head (ASTM D5385 mod.) |
| Roll size | 20 m long x 1.2 / 1.5 / 2.0 m wide, PE-foil wrapped |
| Application / storage temp | Apply +5 C to +40 C; store +5 C to +35 C; 12-month shelf life |
Industry use cases
Metro & Rail Infrastructure
Cut-and-cover station boxes and subway sections where the outer face is permanently buried against retained earth and cannot be rewaterproofed later.
Commercial Basements
Multi-level basement car parks and podium rafts on high water tables in Delhi NCR, where a traceable, locally repairable barrier de-risks the asset.
Deep Foundations
Blindside walls cast against secant or diaphragm pile walls, with reinforcement fixed directly on the bonded membrane to keep the programme tight.
Water & Sump Structures
Lift pits, escalator pits and below-ground tanks where sustained hydrostatic head demands a fully bonded, weldable-seam system.
Premium Residential
Habitable basements in luxury homes and farmhouses that must stay permanently dry and odour-free for gyms, home theatres and storage.
Frequently asked questions
What makes a pre-applied bonded membrane better than a loose-laid sheet?
Can reinforcement be laid directly on the membrane?
How long can the membrane stay down before we cast concrete?
How are the joints sealed?
What depth of water table can it handle?
Does it comply with Indian standards?
How we position Sika SikaProof-315 HDPE SG W IN
SikaProof-315 HDPE SG W IN sits at the heavy-duty end of Sika’s pre-applied range. Where a project needs the same bonded principle but a lighter or thinner build, the SikaProof-312 HDPE SG IN is the natural step within the same family, and detailing accessories such as SikaProof tapes and SikaSwell hydrophilic waterstops complete the system at joints and penetrations. For internal or negative-side sealing of the same structure, pair it with crystalline or cementitious systems like Sika-1 or SikaTop Seal. Space Arc also stocks equivalent bonded membranes from Fosroc and complementary waterproofing from Dr. Fixit and MC-Bauchemie, so we can match the membrane to the consultant’s specification rather than push a single brand.
Fosroc Proofex Engage — Specify Proofex Engage when the design calls for a mechanical cell-mesh key into the concrete and BBA/BS EN 13967 certification rather than an adhesive-bonded HDPE system.
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