Fosroc Proofex 10
A polymer-modified bituminous sheet membrane that seals the ground-facing side of basements, retaining walls and buried structures before backfill goes in.
What is it?
A reinforced, polymer-modified bituminous sheet membrane roughly 3-4 mm thick, supplied in rolls and bonded to the concrete either by gas-torch fusion or with a compatible cold bituminous adhesive.
Where is it used?
On the positive (soil-facing) side of below-ground concrete – basement external walls, retaining walls, lift pits, raft slabs, cut-and-cover tunnels, box culverts and underground car parks – before backfilling.
Why use it?
It forms a continuous, fully bonded tanking barrier that blocks hydrostatic water and ground moisture, so the membrane, not the concrete, does the water exclusion in aggressive or high-water-table ground.
How is it applied?
Prime the sound, dry substrate, then unroll and bond the membrane by torch or adhesive with minimum 100 mm fully fused laps, dressing it around penetrations and construction joints before protection and backfill.
About Fosroc Proofex 10
Proofex 10 belongs to Fosroc’s Proofex family of below-ground tanking membranes, the sheet-based route to waterproofing structures that sit permanently in wet or saturated ground. It is a polymer-modified bitumen compound – the polymers improve ductility, adhesion and behaviour across a working temperature range – carried on a fabric or film reinforcement and delivered in rolls at roughly 3-4 mm thickness. The membrane is installed on the external, ground-facing face of the concrete so that groundwater is stopped at the outside surface and never reaches the structural element. That “positive-side” logic is what separates a tanking membrane like this from an internal crystalline or cementitious coating; here the water is intercepted before it can load the concrete.
For Delhi-NCR and pan-India projects, Proofex 10 suits the classic below-ground brief: a deep basement, a retaining wall against a high water table, a tunnel box or a pile-cap raft that has to stay dry for the life of the building. It is bonded by torch fusion or by cold adhesive, giving the applicator a choice depending on site fire-safety rules and the substrate. Because the sheets are lapped and fused into one another, the finished skin behaves as a single continuous barrier rather than a set of overlapping pieces – provided the laps, upstands and detailing around pipes and construction joints are executed properly. As authorised Fosroc distributors and applicators, Space Arc supplies the membrane alongside the primers, jointing and protection products that make the system work as intended.
The technical insight
The membrane works by exclusion, not by resisting water through the concrete. Bitumen is naturally hydrophobic and effectively impermeable in a continuous film; the polymer modification stops it from becoming brittle in cold weather or slumping in heat, so the sheet stays flexible enough to accommodate minor structural and thermal movement without splitting. The fabric or film reinforcement carries tensile and puncture load, which matters when backfill, protection boards and compaction equipment bear against the wall. The critical engineering detail is continuity: water finds the weakest path, so a below-ground failure almost never comes from the sheet field – it comes from a short lap, a cold or under-fused seam, an unsealed penetration, or a poorly dressed internal corner. That is why the specification calls for minimum 100 mm fully fused laps and full bonding to a primed, sound substrate: full adhesion means that even if the sheet is locally damaged, water cannot track laterally between membrane and concrete to emerge somewhere remote. Get the bond and the laps right and the barrier performs as one continuous, hydrostatically loaded skin.
Where it is used
- External tanking of basement retaining and perimeter walls before backfill
- Waterproofing of raft slabs and pile caps in high-water-table ground
- Cut-and-cover tunnel and underground box-structure external waterproofing
- Lift pits, sumps and other permanently wet below-ground pits
- Buried box culverts and services trenches requiring a continuous barrier
- Underground car park decks and podium-to-basement transitions
- Protection of concrete against aggressive ground salts and moisture ingress
- Bridging construction joints and detailing around pipe and service penetrations
Key advantages
- Positive-side tanking stops water at the external face, so the concrete never carries the hydrostatic load
- Fully bonded sheet limits lateral water tracking behind the membrane if it is locally damaged
- Polymer modification keeps the bitumen flexible across hot and cold Indian site conditions
- Reinforcement gives useful tensile and puncture resistance against backfill and protection boards
- Choice of torch or cold-adhesive bonding suits different fire-safety and substrate situations
- Factory-controlled sheet thickness gives a more consistent build-up than site-applied liquid coats
- Well suited to deep basements, tunnels and other high-water-table structures
- Backed by Fosroc’s wider Proofex system of primers, jointing and protection products
Limitations & considerations
- Positive-side only – it must be applied to the external face before backfill and cannot rehabilitate an existing wet basement from inside
- Performance is highly workmanship-dependent; under-fused laps or unsealed penetrations are the usual failure points
- Torch application introduces an open-flame fire risk and needs trained applicators and hot-work controls
- Requires a sound, dry, primed substrate free of wide cracks; won’t bond reliably to damp, dusty or friable concrete
- The membrane needs protection (boards or screed) before backfill, or aggregate can puncture it
- Detailing at corners, upstands and complex geometry is demanding and best left to experienced applicators
Selection & best practice
Treat the substrate as the make-or-break stage: the concrete must be sound, cured, dry and free of laitance, sharp arrises and cracks wider than about 0.5 mm, with cavities and honeycombing made good first. Prime the surface with the compatible Fosroc primer and let it dry before laying membrane. Bond the sheets fully – by torch fusion or cold adhesive – with a minimum 100 mm fully fused lap at every side and end joint, rolling laps to expel air and confirm a continuous bitumen bleed at the seam. Dress the membrane carefully into internal corners, over construction joints and around every pipe and service penetration using compatible reinforcing/flashing detail, and carry it above the design maximum groundwater level with a proper termination. Protect the finished membrane with protection board or screed before placing and compacting backfill so aggregate cannot puncture it. Avoid torch application near combustibles, keep hot-work permits in place, and do not install onto damp or contaminated substrates.
Specifications
| Product type | Polymer-modified bituminous sheet waterproofing (tanking) membrane |
| Waterproofing side | Positive side (external / ground-facing) |
| Composition | Polymer-modified bitumen on a fabric or film reinforcement |
| Approx. membrane thickness | ~3-4 mm |
| Application method | Torch-applied (heat fusion) or cold bituminous adhesive |
| Minimum lap width | 100 mm, fully fused |
| Substrate | Sound, dry, primed concrete free of wide cracks and laitance |
| Typical structures | Basements, retaining walls, tunnels, rafts, pits, culverts |
Industry use cases
Commercial basements
External tanking of deep multi-level basement walls and rafts under office and retail developments before backfill and landscaping.
Infrastructure & tunnels
Cut-and-cover tunnel boxes, underpasses and buried service structures needing a continuous positive-side barrier in wet ground.
Residential high-rise
Waterproofing of basement car parks, lift pits and raft slabs in apartment projects with a high water table.
Water-retaining & industrial
Below-ground tanks, pits and box culverts where a fully bonded membrane protects concrete from ground salts and moisture.
Retaining structures
Retaining walls and podium-to-basement transitions where the soil-facing face must be sealed before soil is placed against it.
Frequently asked questions
Is Proofex 10 applied inside or outside the basement?
Can it be applied without a gas torch?
How thick is the membrane and how are the sheets joined?
What surface preparation does it need?
Does the membrane need protecting before backfill?
How does it compare with Proofex Torchseal 3P & 4P?
How we position Fosroc Proofex 10
Within the Fosroc waterproofing range, Proofex 10 sits in the sheet-tanking family for below-ground positive-side work. Where a project specifies a heavier, high-reinforcement torch-applied membrane, Proofex Torchseal 3P & 4P (APP-modified, 3/4 mm, polyester-cored) is the natural step up; for a cold, self-adhesive HDPE alternative that avoids hot work, Proofex 3000 or Proofex Engage suit deep tanking and pre-applied “blindside” details. If the requirement is actually a liquid, brush-applied system – for wet areas, terraces or retrofit – our Fosroc Brushbond and Nitoproof coatings, or Dr. Fixit and Sika liquid membranes from our other brand lines, are better matched. Talk to Space Arc and we will specify the correct system, primers and protection for your ground conditions rather than defaulting to a single product.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.