About Fosroc Membrane HDPE-S

Fosroc Membrane HDPE-S is a post-applied, self-adhesive waterproofing membrane built around a high-density polyethylene (HDPE) film carrier with an integral pressure-sensitive adhesive layer. It is engineered specifically for vertical reinforced-concrete members in below-ground structures – the most failure-prone part of any basement, where hydrostatic pressure, ground salts and limited access make remedial repair extremely costly. Supplied as a nominal 1.2 mm thick white sheet, the membrane is unrolled directly onto the prepared, hardened concrete face after the wall has been cast and the formwork stripped. The self-adhesive surface grips the substrate without a separate primer in most conditions, and a self-adhesive selvedge along one edge of each roll lets adjacent sheets be lapped and sealed into one continuous skin.\n\nThe role HDPE-S plays is twofold. First, it excludes liquid water and water vapour from the structure, helping deliver the dry internal environments that BS 8102-style Grade 1, 2 and 3 basements demand. Second, the HDPE carrier is chemically inert, so it protects the concrete from aggressive ground conditions – sulphates and chlorides in the soil, dissolved salts, and hydrocarbon or chemical contamination common on reclaimed, industrial and urban sites. Because the polyethylene does not react with substances ponded in the surrounding ground, the barrier’s performance is stable over the long service life expected of a substructure.\n\nWithin the Fosroc system, HDPE-S is the post-applied vertical counterpart to the pre-applied HDPE-P range (laid against blinding or shuttering before concrete is poured) and the HDPE-S2 underlay variant. It is detailed to integrate with Fosroc’s waterstops, jointing tapes and protection layers, giving a contractor a single compatible family for raft, wall and joint waterproofing rather than a patchwork of unrelated products. For Space Arc Engineering’s Delhi NCR and pan-India clients, that system compatibility – plus genuine, traceable Fosroc material – is the core reason to specify HDPE-S over loose-laid or unbranded HDPE sheet.

The technical insight

The performance of HDPE-S comes from a deliberate split of duties between two layers. The HDPE film is the structural and chemical-resistance layer: high-density polyethylene is non-polar and crystalline, which gives it very low water-vapour permeability and near-total resistance to acids, alkalis, salts and hydrocarbons found in contaminated ground – the same chemistry that makes HDPE the standard for landfill liners. The pressure-sensitive self-adhesive is the bonding layer; it forms an intimate, continuous contact bond with the cast concrete so that even if the sheet is locally punctured, water cannot track laterally between membrane and wall to find another defect. This ‘fully bonded’ behaviour is the single most important property for below-ground work, because it prevents the channelling failures that doom loose-laid membranes. Fosroc characterises its HDPE membranes against a recognised ASTM framework – tensile and elongation to ASTM D412, puncture resistance to ASTM E154, peel adhesion to concrete to a modified ASTM D903, and resistance to hydrostatic head to ASTM D5385 – which lets specifiers compare it like-for-like against international pre-applied systems. The high elongation of the polyethylene film also allows the barrier to bridge minor shrinkage cracks and accommodate small substructure movements without rupturing.

Where it is used

• Waterproofing of basement retaining walls and perimeter substructure walls below the water table
• Vertical RC members in deep basements, lift/elevator pits and machine pits
• Water-retaining and water-excluding structures such as tanks and sumps (external face)
• Podium, raft-upstand and ramp walls requiring a bonded vapour and water barrier
• Protection of concrete in aggressive, salt-laden or sulphate-bearing soils
• Sites with hydrocarbon or chemical ground contamination (reclaimed, industrial, urban infill)
• Integration with Fosroc waterstops and jointing systems at construction and movement joints

Key advantages

• Self-adhesive face bonds directly to cast concrete, generally without a separate primer
• Fully bonded contact stops lateral water tracking between membrane and wall, limiting the spread of any local damage
• Chemically inert HDPE film resists ground salts, sulphates, chlorides, hydrocarbons and dilute chemicals
• Effective barrier to both liquid water and water vapour, supporting dry Grade 1-3 internal environments
• Self-adhesive selvedge along one edge gives quick, reliable sealed laps
• Robust 1.2 mm HDPE film offers good puncture and tear resistance during backfilling
• High film elongation lets the membrane bridge minor shrinkage cracks and movement
• Part of a compatible Fosroc system (waterstops, tapes, pre-applied HDPE-P) for whole-structure detailing
• Cold-applied with no torching, hot works or curing time, so it suits congested basement programmes

Limitations & considerations

• Post-applied to the wall face, so it needs safe external access and an open excavation – less suited to zero-clearance party-wall or back-of-shutter situations where pre-applied HDPE-P is correct
• Requires a sound, dry, clean and reasonably smooth concrete substrate; honeycombing, laitance, dust or dampness compromises the adhesive bond
• Self-adhesive bond is sensitive to temperature and surface moisture; very cold or wet conditions may require a primer or warming and reduce initial tack
• Membrane and laps must be protected promptly and backfill placed carefully to avoid puncture by sharp aggregate or debris
• It is a barrier system, not a crack-injection or structural repair product – active leaks and large cracks must be treated separately before installation
• Overlaps, corners, penetrations and terminations need disciplined detailing; most field failures are workmanship at laps and details, not the sheet itself
• Not a decorative or UV-stable exposed finish – it is intended to be buried/covered, not left permanently exposed to sunlight

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Membrane HDPE-S

Fosroc Membrane HDPE-S is best specified as the post-applied vertical member of Fosroc’s HDPE basement system. On the same job it usually pairs with pre-applied Fosroc Membrane HDPE-P (raft and confined/back-of-shutter faces), the HDPE-S2 underlay variant, and Fosroc waterstops, primers and lap tapes for joints – keeping the whole substructure on one compatible, warrantied family. Where a project instead calls for a torch-applied bituminous system, Fosroc’s own Proofex bitumen-polymer membranes are the in-house alternative. Against the wider market, HDPE-S competes with self-adhesive and pre-applied HDPE/HDPE-bitumen systems such as Sika’s pre-applied sheet membranes (e.g. SikaProof / Sikaplan ranges), STP’s bonded and self-adhesive membranes, Dr. Fixit’s basement waterproofing membranes, and MBS/other Indian HDPE sheet suppliers. HDPE-S’s distinguishing strengths are full adhesive bonding to concrete (limiting lateral water tracking), an inert HDPE film for contaminated and saline ground, and tight integration with the rest of the Fosroc range; its trade-off is that, being post-applied, it needs external access and is not a substitute for pre-applied HDPE-P in zero-clearance conditions. For genuine material plus specification and detailing support in Delhi NCR and pan-India, source it through Space Arc Engineering as an authorised Fosroc distributor.

Related Waterproofing products

View all Waterproofing products →