About Fosroc Geotextile NW

Fosroc Geotextile NW is a thermally bonded nonwoven geotextile from Fosroc’s constructive-solutions range, designed to perform the three classic geotextile duties of separation, filtration and protection within waterproofing and civil-engineering assemblies. The fabric is manufactured from continuous polymer filaments that are mechanically entangled and then thermally bonded, giving it the combination of mechanical robustness and consistent hydraulic behaviour that nonwoven fabrics are valued for. Unlike a finished waterproofing membrane, Geotextile NW is not itself a barrier; rather, it is the supporting fleece that makes a waterproofing or drainage system last, by separating the membrane from aggressive backfill and by managing the flow of water through the soil structure. The “NW” family is offered in a graded series, where the numeric suffix corresponds to the fabric’s characteristic tensile strength in kilonewtons per metre, so a project engineer can step up from a light NW8 separation fleece to a heavier NW32 or NW49 grade where puncture protection and load are more demanding. In Space Arc Engineering’s portfolio it sits alongside the Proofex membrane and Proofex Sheetdrain ranges, completing the below-grade waterproofing build-up. Within India, where basements, metro tunnels, water-retaining structures and highway embankments routinely encounter high water tables, sharp angular backfill and monsoon-driven hydrostatic loads, a correctly specified protection and filtration fleece is the difference between a membrane that survives backfilling and one that is punctured before the structure is even commissioned. Geotextile NW is the component that quietly absorbs that abuse.

The technical insight

The defining feature of a thermally bonded nonwoven is its pore structure: heat-bonding the filaments produces a relatively thin, dimensionally stable fabric with a tight, controlled characteristic opening size (O90), which is what governs filtration. A good filtration geotextile must satisfy two competing demands at once — it has to retain soil fines (a small enough O90 to prevent piping and soil migration) while still passing water freely (high permittivity, so it does not become a hydrostatic dam itself). Fosroc Geotextile NW is engineered around this balance, and its key advantage is that its hydraulic properties promote the formation of a natural soil filter in the adjacent ground over time, which stabilises long-term filtration performance rather than letting the fabric slowly clog. The grade-numbering convention (NW followed by the tensile value in kN/m) is the practical lever an engineer pulls: separation duty in benign soils needs only modest strength, but protecting a single-ply membrane such as Proofex Alkorplan against angular gravel backfill demands a high CBR puncture resistance, which scales with the heavier grades. Because it is thermally rather than needle-punched bonded, the fabric resists delamination and holds its thickness under load, an important property when it must keep a defined drainage gap or cushion thickness in service.

Where it is used

• Protective and separating fleece between Proofex Alkorplan waterproofing membranes and the substrate or backfill in tunnel and basement waterproofing
• Filtration layer wrapping French drains, fin drains and granular drainage blankets to prevent fines migration and clogging
• Separation layer preventing intermixing of subgrade soil and imported aggregate in road sub-bases, hardstandings and access roads
• Cushion and protection layer over membranes during backfilling and protection-screed placement in below-grade structures
• Filtration and separation in landscaped podium decks, planter boxes and green-roof drainage build-ups
• Separation between precast concrete units and waterproofing membranes to accommodate movement

Key advantages

• Performs three functions in one fabric — separation, filtration and membrane protection — simplifying the below-grade build-up
• Thermally bonded construction gives high mechanical robustness and resistance to delamination under load
• Controlled pore structure promotes a self-forming natural soil filter for stable long-term filtration
• Free-draining, helping relieve hydrostatic pressure behind walls and around drains
• Available in a graded range (NW8 to NW49) so strength and puncture protection can be matched to site demands
• Chemically inert and rot-resistant polymer, suited to permanent burial in Indian soil and groundwater conditions
• Compatible with and complementary to Fosroc Proofex membranes and Proofex Sheetdrain drainage composites
• Dry-laid with simple overlapped joints — fast installation, no mixing, mixing ratios or curing time

Limitations & considerations

• It is a separation/filtration/protection fleece, not a waterproofing membrane — it provides no water barrier on its own and must be paired with a Proofex or equivalent membrane
• Filtration performance depends on selecting the correct grade and O90 for the in-situ soil gradation; an over-open fabric can allow piping and an over-tight one can blind and clog
• UV-sensitive like most polyolefin geotextiles — prolonged exposure on site before covering should be avoided
• Lighter separation grades offer limited puncture protection and should not be substituted for heavy protection grades against angular backfill
• Overlaps, anchoring and detailing at penetrations must be executed correctly; a poorly lapped fleece can let soil bypass the filter
• Not a structural reinforcement geogrid — high-tension soil-reinforcement applications require a purpose-made reinforcement product

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Geotextile NW

Fosroc Geotextile NW is the protection-and-filtration companion to Fosroc’s below-grade waterproofing systems — it is most naturally specified alongside Proofex Alkorplan membranes (which it separates and shields) and Proofex Sheetdrain drainage composites, with the heavier-duty Fosroc Geotextile SNW range available where greater robustness is needed. As a nonwoven geotextile it competes with general geosynthetic brands commonly seen on Indian sites such as Garware, Strata, TechFab, Maccaferri and Terram, as well as the protection fleeces bundled with rival membrane systems from Sika, MBCC/MBS (formerly BASF), Dr. Fixit (Pidilite) and STP Ltd. The honest case for Geotextile NW is system compatibility: when the waterproofing membrane is Fosroc Proofex, using the matched Fosroc geotextile keeps the build-up within a single manufacturer’s warranty and technical envelope. Where a project is membrane-agnostic or driven purely by geotextile specification (a target O90, mass per unit area and CBR puncture value), a dedicated geosynthetics supplier may offer a wider grade ladder and project-specific certification, and that is a legitimate alternative. For Fosroc-membrane basements, tunnels and water-retaining structures, however, Geotextile NW is the path of least risk and cleanest accountability.

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