Dr. Fixit Prebond S
The pre-applied HDPE membrane that bonds itself to your basement slab before a single drop of concrete goes in.
What is it?
A preformed, pre-applied HDPE waterproofing membrane with a pressure-sensitive adhesive face that fuses to the underside of concrete as it’s poured on top of it.
Where is it used?
Basement rafts, pile caps and confined blindside retaining walls, metro/subway underground boxes, lift pits and other below-ground structures where waterproofing has to go in before the pour and can never be reached again once buried.
Why use it?
It’s installed ahead of the concrete, so there’s no membrane to protect through the pour and no risk of it separating from the structure later — the adhesive activates on contact with wet concrete and locks on, stopping water from tracking sideways underneath even if the ground below settles.
How is it applied?
Rolled out over compacted PCC blinding or a shutter-faced vertical surface with the adhesive side facing the coming pour, sheets overlapped 100 mm along the marked selvedge with the release liner peeled off only at the laps, then reinforcement is fixed and concrete cast directly on top.
About Dr. Fixit Prebond S
Any basement, lift pit or underground metro box shares the same headache: once the raft is poured and the walls go up, you can never get back to the outside face of that concrete to fix a leak. That’s why “blindside” or positive-side waterproofing has become the default specification on deep foundations across Delhi NCR and most metro-rail contracts — the membrane has to go down before the concrete, not after, and it has to bond hard enough to the slab that ground water can’t creep sideways underneath it even years later.
Dr. Fixit Prebond S (Pidilite’s rebrand of the earlier Dr. Fixit Prebond) is built around exactly that idea. It’s a factory-made HDPE sheet carrying a pressure-sensitive adhesive layer under a sand-particulate weather coat — you roll it out over PCC blinding or a plywood/shutter face, lap the sheets 100 mm along the marked selvedge, and place reinforcement straight on top. There’s no separate protection screed to cast. When ready-mix hits the membrane, the adhesive activates and fuses permanently to the underside of the raft, so the finished structure has an integral, tracking-free seal rather than a loose sheet sitting against it. It’s rated for IS 16471:2017 and BS 8102:2022 Type A protection, carries a 70 m hydrostatic-head rating, and tolerates up to 45 days of UV exposure before burial — a realistic cushion for how Indian basement programmes actually slip.
The technical insight
What makes Prebond S work is the sequencing, not just the material. Conventional post-applied membranes rely on adhesion to a finished concrete face — surface laitance, dust and moisture at the time of application all become variables. Prebond S sidesteps that by putting the bond decision in the hands of the concrete itself: the pressure-sensitive adhesive under the HDPE film stays inert (protected by the sand-particulate weather layer) until fresh concrete is cast directly onto it, at which point it activates and fuses to the setting slab. The result is a mechanically continuous interface rather than a surface-applied coating, which is why the data sheet can claim the membrane “is unaffected by substrate settlement” — there’s no separate bond line to fail if the ground beneath moves. The 70 m hydrostatic-head rating (ASTM D5385) and 1500 N/m peel adhesion (ASTM D903) are the numbers that matter most for basement specifiers, since they set how deep and how tightly bonded the system can go before ground-water pressure or lap separation becomes a risk. IS 16471:2017 and BS 8102:2022 both classify this as Type A — barrier — protection, meaning the waterproofing is provided entirely by the membrane’s continuity rather than by the concrete’s own impermeability (Type B) or a managed drainage cavity (Type C); that classification is what should drive whether it’s specified alone or combined with another protection type on a given project.
Where it is used
- Basement raft and pile-cap waterproofing, laid over PCC blinding before rebar is fixed
- Confined (blindside) retaining walls against plywood shuttering, masonry or excavation-support facing with no future outside access
- Underground metro station boxes, subway structures and diaphragm-wall-lined basements on infra projects
- Lift pits, sump pits and other localised excavations sitting below the water table
- Multi-level basement rafts under high-rise residential and commercial towers in Delhi NCR
- Perimeter walls and rafts of underground water/sewage-treatment tanks exposed to aggressive ground salts
- Podium-level basements in IT parks and mixed-use developments where the raft is cast in one continuous pour
- Culvert and box-structure waterproofing on civil infrastructure works
Key advantages
- Self-activating adhesive bonds directly to wet concrete, so there’s no separate primer or bonding-agent step before the pour
- Integral fusion with the slab (not a loose-laid sheet) stops lateral water tracking even if the membrane is nicked somewhere along the run
- Bond is unaffected by later substrate settlement, unlike loose-laid or torch-applied systems that can pull away from a shifting subgrade
- Reinforcement and concrete go straight on the membrane — no screed or protection board, which saves a full work sequence and its cost
- 70 m hydrostatic head rating (ASTM D5385) covers the ground-water pressures seen on deep multi-level basements and metro boxes
- Complies with IS 16471:2017 and BS 8102:2022 recommendations for Type A (barrier) protection, useful for consultants sign-off
- 2.0 m and 2.4 m roll widths mean fewer laps per square metre and a faster lay-down rate than narrower membranes
- 45-day UV exposure tolerance gives real headroom against the reinforcement-fixing and casting delays common on Indian sites
Limitations & considerations
- It’s a Type A (barrier) protection system — for basements needing higher water-tightness grades, BS 8102 typically calls for combining it with a structurally integral (Type B) or drained-cavity (Type C) approach, not using it alone
- Being a positive-side, pre-applied system, it can’t be retrofitted onto a structure that’s already cast without excavating back to the outer face
- Performance depends almost entirely on installation discipline — lap widths, corner detailing and tape-sealing any opened patches; poor site supervision undermines the whole integral-seal concept
- The adhesive layer can feel slightly tacky underfoot in hot weather, which is normal per the data sheet but needs the site crew briefed so tools and wheelbarrows don’t drag or damage the sheet before the pour
- It needs a reasonably firm, clean substrate — loose aggregate or sharp protrusions on the blinding concrete can affect the membrane’s puncture resistance
- UV tolerance is rated to 45 days; programme delays that leave it exposed longer than that need a protective cover, which isn’t always accounted for in the schedule
Selection & best practice
Treat the blinding concrete as part of the waterproofing system, not just a working platform — it should be reasonably level, free of loose aggregate and sharp protrusions, with standing water removed (it doesn’t need to be bone dry). Lay the membrane with the HDPE film facing the substrate and the adhesive facing the coming pour, stagger end laps so overlaps don’t stack up in one spot, and hold the 100 mm selvedge overlap religiously — this is where nearly every on-site leak actually originates, not in the field of the sheet. Peel the release liner only at the laps, roll every joint firmly with a heavy roller to kill air pockets, and treat internal/external corners as a separate detail: pre-form them with a minimum 100 mm overlap and seal with Dr. Fixit Pre-Bond Tape rather than improvising with the flat sheet. Any patch opened up for a fixing or a service penetration should be heat-welded or taped back, and vertical runs should be mechanically fixed through the selvedge only, with fixings covered by a tape patch. Finally, brief the site crew that the membrane can feel tacky underfoot in hot weather — normal residual adhesive, but workers should avoid dragging tools or wheelbarrows across it before the pour.
Specifications
| Composite thickness | 1.5 mm or 1.8 mm (ASTM D3767) |
| Bare HDPE film thickness | 0.9 mm (1.5 mm variant) / 1.2 mm (1.8 mm variant) |
| Tensile strength, bare HDPE film | 25 MPa (1.5 mm) / 28 MPa (1.8 mm), ASTM D412 |
| Elongation, bare HDPE film | 500%, ASTM D412 |
| Puncture resistance | 1000 N (1.5 mm) / 1500 N (1.8 mm), ASTM E154 |
| Resistance to hydrostatic head | 70 m, ASTM D5385 |
| Peel adhesion to concrete | 1500 N/m, ASTM D903 |
| Water vapour transmission rate | 0.1 g/m²/hr, ASTM E96 |
| Roll size / packaging | 20 m x 2.4 m or 20 m x 2.0 m @ 1.5 mm; 20 m x 2.4 m @ 1.8 mm |
Industry use cases
Metro rail & subway infrastructure
Blindside waterproofing to underground station box rafts and diaphragm-wall-lined basements ahead of reinforcement fixing, using the 45-day UV tolerance to absorb phased construction schedules.
Residential high-rise basements
Raft waterproofing under multi-level basements across Delhi NCR, laid over PCC blinding before rebar so reinforcement and concrete go straight on without a separate protection screed.
Commercial & IT park podiums
Confined retaining-wall waterproofing against plywood or masonry shuttering on sites where the excavation face gives no future access once backfilled.
Water & sewage treatment structures
Rafts and perimeter walls of underground tanks exposed to aggressive ground-water conditions, where the 70 m hydrostatic-head rating and chemical resistance matter.
Lift pits & sump pits
Localised excavations sitting below the water table needing positive-side external tanking that can’t be retrofitted once cast.
Frequently asked questions
How is Prebond S different from a waterproofing coating applied after the slab is cast?
Does the blinding concrete or shutter face need to be dry before we lay the membrane?
Can Prebond S be used on vertical retaining walls, or only on rafts?
What if the membrane gets torn or a hole gets cut into it on site?
What roll sizes does it come in, and how much should we allow for laps?
Does specifying Prebond S alone satisfy the waterproofing requirement, or do we need something else with it?
How we position Dr. Fixit Prebond S
Within the Dr. Fixit range, Prebond S sits alongside Prebond E and Prebond Pro (other pre-applied membrane variants for different substrate and exposure conditions), Prebond W (an HDPE membrane format for related blindside applications) and the Prebond DS Tape / Pre-Bond Tape accessories used for its own laps and corner details — Space Arc typically specifies the tape alongside the membrane as a single system rather than sourcing seals separately. Against the wider market, the nearest genuine equivalent is Fosroc’s Proofex Engage, which achieves its bond mechanically via a cell mesh rather than an adhesive layer and carries certified gas-resistance (methane, CO2, radon) that Prebond S’s data sheet doesn’t claim — a relevant swing factor on brownfield or landfill-adjacent sites. For projects where the priority is fast, adhesive-based bonding with a strong IS 16471:2017 / BS 8102:2022 Type A track record on Indian metro and basement work, Prebond S remains the more commonly specified option.
Fosroc Proofex Engage — Where a specifier wants a mechanically-interlocking pre-applied membrane with certified methane/radon gas resistance alongside water-tightness — rather than an adhesive bond to the concrete — Fosroc’s cell-mesh Proofex Engage is the credible alternative to evaluate against Prebond S.
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