Sika Sarnacol-2170
Solvent-based contact adhesive engineered to bond Sika Sarnafil and Sikaplan single-ply PVC membranes to roof decks, upstands and detailing.
What is it?
A one-part, solvent-based contact adhesive built on a nitrile-rubber binder, formulated by Sika specifically to bond its Sarnafil G and Sikaplan single-ply PVC roofing membranes.
Where is it used?
Adhered flat-roof waterproofing on warehouses, podiums and commercial decks, plus upstands, parapets and flashing details where mechanical fixing is not practical.
Why use it?
It gives a high-strength, full-surface bond that lets the membrane resist wind uplift without penetrating the deck, keeping the waterproofing layer continuous.
How is it applied?
Brush or roller applied to both the substrate and the membrane back; the solvent is allowed to flash off to a tacky finish before the two faces are mated under pressure.
About Sika Sarnacol-2170
Sika Sarnacol-2170 sits at the join between the roof deck and the waterproofing membrane, and on an adhered single-ply system that join is where the whole assembly earns or loses its wind rating. It is a one-part, solvent-based contact adhesive carried on a nitrile-rubber binder, and it was developed by Sika for one job in particular: fixing Sarnafil G-type, G Felt-type and Sikaplan PVC membranes onto a prepared substrate. Because it is a contact adhesive rather than a wet-set mortar, the installer coats both faces, waits for the solvent to flash, and then brings the surfaces together, at which point the bond develops quickly and holds the sheet flat against the deck.
For the specifier the appeal is a fully adhered roof with no fasteners driven through the membrane, which keeps the waterproofing continuous and removes the thermal-bridge and leak-path concerns that come with mechanical attachment. Space Arc Engineering supplies Sarnacol-2170 as part of the Sika Sarnafil roofing package across Delhi NCR and pan-India, and we treat it as a system component rather than a generic glue: it is matched to a specific membrane, a specific set of substrates and a defined weather window, and it performs as intended only when those conditions are respected on site.
The technical insight
A contact adhesive works differently from a mortar or a moisture-cure sealant. The high-solids formulation (around 77% by weight) carries the nitrile-rubber polymer in a solvent; once spread thin on both the deck and the underside of the PVC sheet, the solvent evaporates and leaves two tacky rubber films. When those films are pressed together they knit into a single elastic layer almost immediately, which is why the membrane can be positioned, mated and loaded in one pass without waiting for a chemical cure. The nitrile base is deliberate: it stays flexible across roof-temperature swings, resists the plasticisers migrating out of soft PVC, and holds shear as the membrane expands and contracts. The trade-off is that the whole mechanism depends on getting the flash-off right. Mate the faces too early and trapped solvent leaves a weak, spongy bond; leave them too long and the films skin over and will not knit. That is also why the +5 °C floor on air and substrate temperature matters, cold slows evaporation and can leave solvent in the film, and why absorbent decks drink up to 1000 g/m² while dense surfaces need only 300-500 g/m².
Where it is used
- Fully adhered Sarnafil and Sikaplan single-ply PVC roofs on warehouses, factories and large commercial buildings
- Bonding membrane upstands, parapets, kerbs and flashing details where mechanical fixing is awkward
- Roof waterproofing installed over PUR/PIR insulation boards
- Fixing membrane onto concrete podium decks and terraces
- Re-roofing and refurbishment with a new adhered single-ply membrane
- Bonding to timber-based decks such as OSB and plywood
- Membrane attachment to fibre-cement and mineral-fibre board substrates
- Detailing around penetrations, rooflights and rooftop plant
Key advantages
- Delivers a fully adhered roof with no fasteners piercing the membrane, keeping the waterproofing layer continuous
- Nitrile-rubber base stays flexible and resists plasticiser migration from soft PVC over the roof’s life
- High solids content (~77%) lays down a substantial rubber film per coat
- Bonds a wide range of decks: concrete, masonry, timber boards, fibre-cement and PUR/PIR insulation
- Rapid grab on mating means the membrane can be positioned and loaded without a long cure wait
- One-part product, ready to use straight from the container with brush or roller
- Long 24-month shelf life in sealed containers eases procurement and site logistics
- Purpose-matched to Sika Sarnafil / Sikaplan membranes for a warrantable single-supplier system
Limitations & considerations
- Solvent-based with a high VOC content, so it needs good ventilation and cannot be used in confined or poorly aired spaces
- Flammable during application and until the solvent has fully flashed off; open flames and hot works must be excluded
- Not suitable for EPS or XPS insulation, which the solvent attacks, nor for copper, bituminous or most other membrane substrates
- Application is limited to air and substrate temperatures of at least +5 °C, ruling out cold-weather bonding without protection
- Bond quality is highly dependent on correct flash-off timing and clean, dry, dust-free surfaces
- Purpose-built for Sika PVC membranes, it is not a general-purpose adhesive for unrelated sheet materials
Selection & best practice
Start with a substrate that is sound, clean, dry and free of dust, oil and loose material, then confirm both the air and the surface are at +5 °C or above and rising. Decant and stir the adhesive, and apply an even film to the substrate with a brush or short-nap roller; for bareback membrane, coat the underside of the sheet as well. Let each coated face flash off until it is tacky to a dry finger but no longer wet, this window is the single most important control on bond strength. Mate the membrane into the adhesive, working out air and pressing or rolling the full surface to wet-out the bond. On very absorbent decks expect consumption toward 1000 g/m² and a second coat where the first sinks in; on dense surfaces 300-500 g/m² is typical. Keep containers closed between uses to preserve solvent, exclude all ignition sources, and never bond to EPS/XPS or damp substrates. Always follow the current Sika Product Data Sheet and the specified Sarnafil/Sikaplan system detail.
Specifications
| Product type | One-part solvent-based contact adhesive |
| Binder / chemistry | Nitrile-rubber based |
| Solids content | Approx. 77% by formulation |
| Density | Approx. 0.90 kg/L at +20 °C |
| Consumption | 300-500 g/m² on normal substrates; up to 1000 g/m² on very absorbent surfaces |
| Application temperature | Air and substrate at least +5 °C |
| Application method | Brush or roller; contact bonding |
| Pack sizes | 5 kg and 20 kg containers |
| Shelf life | 24 months in sealed, original containers |
Industry use cases
Warehousing & logistics
Large adhered Sarnafil roofs on distribution sheds where a fastener-free, continuous membrane resists wind uplift over big spans.
Commercial & institutional
Adhered single-ply waterproofing on offices, malls and public buildings, including parapets and detailing that cannot be mechanically fixed.
Podium & terrace decks
Bonding membrane onto concrete podium decks and landscaped terraces where penetrations through the slab must be avoided.
Roof refurbishment
Re-covering ageing roofs with a new adhered PVC membrane over retained or replaced insulation during refurbishment.
Insulated flat roofs
Fixing membrane over PUR/PIR insulation boards to build a warm-roof buildup on commercial and industrial buildings.
Frequently asked questions
What is Sika Sarnacol-2170 used for?
How much adhesive do I need per square metre?
Which substrates can it bond to, and which should I avoid?
What is the minimum temperature for application?
How do I get the bond timing right?
What pack sizes and shelf life does it have?
How we position Sika Sarnacol-2170
Sarnacol-2170 is a system component in Sika’s Sarnafil single-ply roofing line and is best specified alongside the membrane it is made for, Sika’s Sarnafil G and Sikaplan PVC sheets, together with the matching Sarnafil detailing accessories, seam-welding equipment and edge trims for a warrantable single-supplier roof. Where a project needs a lower-VOC or water-based bonding route, or fixing to EPS/XPS insulation that this solvent adhesive cannot touch, ask us about the alternative Sarnacol and Sarnabond options in the same Sika family. For the wider building envelope, Space Arc pairs the roof with our other brands: Fosroc for cementitious deck waterproofing, screeds and concrete repair beneath the membrane, and Dr. Fixit or MC-Bauchemie systems for podium tanking and below-grade waterproofing where a liquid or cementitious system suits better than a single-ply sheet. Because Fosroc’s adhesives are epoxy and acrylic concrete bonding agents rather than PVC-membrane adhesives, there is no like-for-like Fosroc substitute for this product; talk to our technical team to match the right adhesive to your membrane and deck.
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