Sika Igolflex 1K
One-component, cold-applied polymer-bitumen emulsion for damp-proofing and waterproofing below-grade concrete, foundations and masonry.
What is it?
A ready-to-use, single-component rubberised-bitumen emulsion that dries to a seamless, flexible black membrane over concrete and masonry.
Where is it used?
Foundations, retaining walls, basement and plinth exteriors, footings, planter boxes and other below-ground or backfilled surfaces.
Why use it?
It shields buried structures from soil moisture, dampness and mildly aggressive ground salts without heating, torching or joints.
How is it applied?
Stir and apply cold in two coats by brush, trowel or spray on a clean, sound, slightly damp substrate, then protect before backfilling.
About Sika Igolflex 1K
Sika Igolflex 1K is a one-component, water-based polymer-bitumen (rubberised bitumen) emulsion supplied ready to use as a thick, brushable black paste. Applied cold and without any site mixing of separate liquid and powder components, it dries into a tough, seamless film that clings tightly to concrete and masonry and keeps out the dampness, capillary moisture and mildly aggressive salts that migrate through soil against buried structures. Because it is a single-pack product, there is no mix ratio to get wrong, no pot life to race against, and no gas torch or hot bitumen kettle on site, which makes it a straightforward choice for foundation and basement exterior work where speed and safety matter.
For the engineer or applicator, the appeal is a continuous, joint-free barrier that flexes with the substrate rather than a lapped sheet that can peel or debond at seams. Igolflex 1K bonds directly to green or matured concrete, plaster, blockwork and brick, tolerates a slightly damp surface, and remains flexible enough to bridge fine shrinkage cracks that inevitably open in below-grade elements. It sits in the damp-proofing and tanking family of coatings: excellent as protection against soil moisture and non-pressurised water, and best specified alongside a drainage or protection layer where the design has to deal with a real head of groundwater.
The technical insight
The performance comes from the rubber-modified bitumen dispersed in the water phase of the emulsion. When the coating is applied, the water evaporates and the bitumen particles coalesce into a homogeneous film in which the rubber component stays elastic. That elastomer content is what lets a cured bitumen film stretch and recover instead of cracking, giving high elongation and the crack-bridging behaviour that a plain solvent-bitumen paint cannot offer. Bitumen itself is naturally hydrophobic and chemically stable against the chlorides, sulphates and dilute acids typically found in soil and groundwater, so the film resists the exact agents that attack buried concrete and reinforcement. Building the specified film thickness in two or more coats is essential: waterproofing integrity is a function of continuous dry-film thickness, and thin or pin-holed application is where below-grade coatings fail. Applied over a sound, well-detailed substrate and cured before backfill, the membrane works as a fully bonded skin that stops water tracking laterally behind it.
Where it is used
- Damp-proofing the outer face of basement and foundation walls before backfilling
- Coating footings, pile caps and ground beams against soil moisture
- External waterproofing of retaining walls and earth-retaining structures
- Protective coating for buried concrete against chlorides, sulphates and dilute ground chemicals
- Damp-proof course (DPC) treatment at plinth level to break rising dampness
- Waterproofing and lining of planter boxes and landscaped earth-retaining features
- Vapour and damp barrier behind cladding, stone facing and rendered facades
- Protecting embedded pipework, ducts and cement blockwork from moisture ingress
Key advantages
- One-component and ready to use, so there is no on-site mixing, no dosing errors and no pot-life pressure
- Cold-applied by brush, trowel or spray, eliminating gas torches, hot kettles and open-flame risk
- Seamless, fully bonded film with no laps or joints that can peel or leak
- Rubber content gives real flexibility and crack-bridging over fine substrate movement
- Bonds to both dry and slightly damp concrete, plaster, blockwork and brick
- Water-based and low-odour, safer to handle in confined foundation trenches than solvent coatings
- Resists soil-borne chlorides, sulphates, saltwater and dilute chemicals attacking buried concrete
- Fast successive coats in warm Indian conditions keep foundation and basement programmes moving
Limitations & considerations
- Not designed to resist a standing head of hydrostatic water pressure on its own; a positive-side pressure situation needs a system built for that duty
- Must be protected with a drainage board, protection sheet or screed before backfill compaction, or aggregate can puncture the film
- Being water-based, it cannot be applied during rain and fresh coats must be shielded until dry
- Full curing takes a few days depending on temperature, humidity and thickness before backfilling
- Not intended for permanent water immersion or direct potable-water contact
- Waterproofing depends entirely on achieving continuous specified dry-film thickness; thin or pin-holed coats will leak
Selection & best practice
Start with a sound, clean substrate: remove dust, laitance, oil, curing compounds and loose material, and repair honeycombing, blowholes and cracks first. Round off sharp arrises and form a fillet at wall-to-slab junctions so the coating turns the corner without thinning. Detail all corners, construction joints and pipe penetrations with a stripe coat before the main areas. Stir the pail thoroughly to a uniform colour and apply cold in a minimum of two coats, working the second coat at right angles to the first to close pinholes and even out the build. Let each coat dry until touch-dry before overcoating, and do not apply if rain is expected. Once fully cured, always install a protection or drainage layer before backfilling and compact the fill carefully so the membrane is not damaged.
Specifications
| Product type | One-component (1K), water-based polymer/rubberised-bitumen emulsion coating |
| Form / colour | Ready-to-use thick paste; black / dark brown when dry |
| Application | Cold-applied by brush, trowel or spray; no heating or torching |
| Coats | Minimum two coats (a third for very porous substrates or added build) |
| Consumption | Approx. 0.6–0.9 kg/m² per coat; around 1.8 kg/m² for ~1 mm dry film in two coats |
| Flexibility | High elongation with crack-bridging from rubber content |
| Chemical resistance | Resistant to chlorides, sulphates, saltwater and dilute chemicals in ground |
| Overcoating / cure | Recoat after the previous coat is touch-dry; full cure typically a few days by temperature and humidity |
| Substrate condition | Sound, clean concrete or masonry; dry or slightly damp, no standing water |
Industry use cases
Residential & Commercial Basements
Applied to the external face of foundation and basement walls as a bonded damp-proofing skin before backfill, keeping soil moisture out of habitable below-grade space.
Infrastructure & Bridges
Protects buried concrete such as footings, pile caps, abutments and retaining walls from ground moisture and aggressive soil salts on road and structure projects.
Industrial & Warehousing
Damp-proofs plinths, ground beams and blockwork below DPC level so rising dampness does not reach floors and stored goods in factory and godown builds.
Landscape & Urban Development
Lines planter boxes, terrace gardens and earth-retaining features so retained soil and irrigation moisture cannot track into the surrounding structure.
Water & Services Trenches
Coats embedded ducts, service trenches and buried blockwork, shielding them from moisture ingress and mild ground chemical attack.
Frequently asked questions
Is Sika Igolflex 1K a single-pack product, or do I mix two components?
Can it hold back groundwater under pressure?
Do I need a gas torch or hot bitumen for it?
Can I apply it on a damp surface after monsoon?
How much do I need, and in how many coats?
Does the coating get damaged when the trench is backfilled?
How we position Sika Igolflex 1K
Sika Igolflex 1K sits in the below-grade damp-proofing and tanking part of the Sika Igolflex waterproofing family. Where a project needs an under-tile or wet-area liquid membrane rather than a buried damp-proof coat, Sika Igolflex-301 Waterproof IN is the one-component elastomeric membrane to specify, and for cases demanding a two-component, higher-build below-grade system Sika’s 2K Igolflex options step up the duty. When a job calls for a positive-side cementitious tanking coat, Sika’s SikaTop and Sika MonoTop range complements the bituminous approach. Across our other brands, Fosroc’s bituminous below-ground line and Dr. Fixit’s damp-proofing coatings cover the same use cases, so we can match the right chemistry and pressure rating to your site rather than force a single product.
Fosroc Nitocote EB83 — Specifiers standardised on Fosroc for a project may prefer Nitocote EB83, an equivalent bitumen-based below-ground protective and waterproof coating for foundations and embedded steelwork.
Related Waterproofing products
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