Sika SikaShield W159 ED 1.5mm
A 1.5 mm wet-applied bituminous membrane that bonds fully to green or damp concrete with SikaShield W1 mortar, giving basements and retaining walls a fully adhered, flame-free tanking layer.
What is it?
A 1.5 mm cross-laminated PE-reinforced bituminous sheet membrane that is wet-applied to concrete using SikaShield W1 adhesive mortar, with no torch or flame required.
Where is it used?
Below-ground tanking for basements, lift pits, vertical RCC retaining and basement walls, and single or strip foundations, as a standalone layer or a base sheet in multi-layer systems.
Why use it?
Full-contact adhesion to the structure limits lateral water tracking, so a puncture or defect stays local instead of migrating across the whole slab or wall.
How is it applied?
SikaShield W1 mortar is applied to the prepared, damp substrate, then the membrane is bedded into it, lapped, and rolled out; laps are sealed and the layer is cured before backfilling.
About Sika SikaShield W159 ED 1.5mm
SikaShield W159 ED 1.5mm is Sika’s answer to a recurring problem on Indian basement and below-ground jobs: how to get a reliable, fully bonded waterproofing layer onto concrete that is still green, damp, or sitting in a tight excavation where an open flame is out of the question. Rather than torching a felt or loose-laying a sheet, the membrane is wet-applied. SikaShield W1, a purpose-made adhesive mortar, is spread onto the substrate and the 1.5 mm bituminous sheet is bedded straight into it. The result is a continuous, adhered skin rather than a membrane floating on the structure.
The sheet itself is built around a cross-laminated polyethylene film. That reinforcement is what gives the membrane its working mechanical properties, elongation of around 300 percent, roughly 3 N/mm2 tensile strength, and static puncture resistance near 240 N, so it can bridge minor movement and shrugs off site knocks during backfill. Both faces carry a removable liner over the adhesive compound, which keeps handling clean and speeds up lapping on the wall or slab. Supplied in 1.0 m by 20.0 m rolls with a 12-month shelf life when stored vertically between +5 C and +35 C, it is a system product: the membrane and the W1 mortar are specified and installed together, not as separate off-the-shelf items.
The technical insight
The performance logic here is full-contact adhesion. Loose-laid or spot-bonded membranes leave a void between the sheet and the concrete; if water finds a single breach, it can travel through that void and reappear metres away, which is why blind-side leaks are so hard to chase. Wet-applying the sheet into SikaShield W1 mortar removes that continuous void. Independent lateral water migration resistance of roughly 70 metres reflects how far water can track along the bond line before it is arrested, so a localised defect tends to stay localised. The cross-laminated PE core does the structural work: cross-lamination orients the film in two directions, spreading tensile and puncture loads rather than letting them concentrate on a single axis. Elongation to around 300 percent lets the membrane accommodate settlement and thermal movement in the substrate without splitting, and low-temperature flexibility down to about -25 C means it will not turn brittle in cold conditions or cold stores. Because there is no flame in the process, it works in confined pits and near existing services where torch-on systems are simply unsafe.
Where it is used
- Tanking to basement rafts, retaining walls and lift pits below the water table
- Vertical RCC basement and retaining walls where a fully bonded external skin is specified
- Single and strip foundation waterproofing on residential and commercial builds
- Base sheet in multi-layer bituminous waterproofing systems
- Below-ground structures in confined excavations that demand flame-free installation
- Tanking beneath heavy protection screeds or protection boards before backfill
- Waterproofing to damp or freshly cast concrete where drying-out time is not available
- Podium and buried-structure decks that will be permanently covered, not left exposed
Key advantages
- Wet-applied with SikaShield W1 mortar, so no torch, flame or hot works on site
- Full-contact bond to the structure limits lateral water tracking behind the membrane
- Bonds to damp and green concrete, cutting the wait for substrate drying
- Cross-laminated PE reinforcement delivers ~300% elongation and ~240 N puncture resistance
- Peel-off liners on both faces keep laps clean and speed up installation
- Stays flexible to about -25 C, so it will not crack in cold conditions
- Handy 1.0 m x 20.0 m roll format is manageable for wall and confined-space work
- Backed by Sika’s global waterproofing track record and technical support
Limitations & considerations
- Not suitable for roofs or surfaces permanently exposed to UV; it must stay buried or covered
- Performs as a system with SikaShield W1 mortar, so the adhesive must be specified and costed alongside the sheet
- Application window is +5 C to +50 C at max 80% RH; hot, humid monsoon spells need scheduling care
- Needs a minimum 24 h cure at +25 C before backfilling and backfill within 7 days, which adds a hold point to the programme
- Substrate preparation is critical, a poorly cleaned or loose surface undermines the bond that the system relies on
- As a below-ground membrane it must be protected against backfill damage with a screed or protection board
Selection & best practice
Treat W159 ED as a bonded system, not a peel-and-stick sheet. Prepare the concrete first: remove laitance, curing compound residue, dust and sharp protrusions, and fill blowholes and honeycombing so the mortar has full contact. The substrate can be damp but should be sound and even. Apply SikaShield W1 mortar to the area you can cover before it skins, bed the membrane into it, and roll out firmly to expel air and guarantee full adhesion, working the laps carefully since overlaps are the usual leak path. Keep installation within +5 C to +50 C and below 80 percent RH; on hot afternoons, work smaller bays. After completion, hold for at least 24 hours of cure at +25 C, then backfill within 7 days behind a protection screed or board so the membrane is never left exposed to sun or mechanical damage. Detail junctions, pipe penetrations and construction joints with the appropriate Sika reinforcing and sealing accessories rather than relying on the field sheet alone.
Specifications
| Membrane type | Wet-applied bituminous waterproofing membrane |
| Thickness | 1.5 mm (+/- 0.15 mm) |
| Reinforcement | Cross-laminated polyethylene (PE) film |
| Elongation | 300% (+/- 10%) |
| Tensile strength | 3 N/mm2 (+/- 10%) |
| Static puncture resistance | 240 N (+/- 10%) |
| Joint peel resistance | 400 N/m (+/- 10%) |
| Low-temperature flexibility | Unaffected at -25 C |
| Lateral water migration resistance | Approx. 70 m |
| Roll size | 1.0 m x 20.0 m |
| Shelf life | 12 months, stored vertically at +5 C to +35 C |
Industry use cases
Residential basements
Full external tanking to basement rafts and retaining walls on villas and apartment builds, bonded to green concrete so the pour-to-waterproofing gap on the programme is minimised.
Commercial and mixed-use
Below-ground car parks, lift pits and services rooms where a fully adhered membrane is specified to contain any future leak to a small, traceable area.
Infrastructure and utilities
Buried tanks, pump chambers and confined structures where flame-free installation is a safety requirement near existing services.
Foundations
Single and strip foundation waterproofing on sites with a high water table, used as a standalone bonded layer under protection.
Multi-layer systems
As the bonded base sheet beneath heavy protection or additional membrane plies on demanding below-ground waterproofing specifications.
Frequently asked questions
Does SikaShield W159 ED need a torch or flame to install?
Can it be applied to damp or freshly cast concrete?
What adhesive does it use, and is it included?
Can I use it on an exposed roof?
How long before I can backfill?
What sizes does it come in and how should it be stored?
How we position Sika SikaShield W159 ED 1.5mm
SikaShield W159 ED 1.5mm sits in Sika’s wet-applied bituminous tanking range and is designed to be used with its companion SikaShield W1 adhesive mortar; specify the two together. Where a project needs a thicker or multi-layer build-up, or reinforcing and sealing at junctions, penetrations and construction joints, pair it with the appropriate Sika accessories and Sikaplan or Sika bituminous ancillaries. For internal or positive-side jobs, or where a cementitious tanking slurry suits the detail better, Sika’s cementitious waterproofing range is the more logical route than a bonded sheet. Across our other brands, Dr. Fixit and Fosroc both offer below-ground membrane and coating systems that specifiers standardise on for particular clients, so the choice often comes down to approved-vendor lists as much as performance.
Fosroc Proofex 3000MR — Choose the Fosroc self-adhesive membrane when the below-ground structure also needs certified resistance to ground gases such as methane, radon and carbon dioxide, which the SikaShield wet-applied system is not specified for.
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