Sika Sikalastic-10 Primer EP
A solvent-free, two-component epoxy primer that anchors Sikalastic liquid membranes and SikaShield bituminous systems to concrete, screed and metal decks.
What is it?
A two-component, 100% solids, solvent-free epoxy primer engineered as the bonding layer beneath Sika liquid-applied and bituminous roofing membranes.
Where is it used?
Roof decks, podiums, terraces, cement screeds and metal substrates that will receive Sikalastic or SikaShield waterproofing systems.
Why use it?
Its low viscosity drives deep into the substrate to lock down dust and stabilise the surface, delivering concrete-failure adhesion above 1.5 N/mm2 so the membrane never lifts.
How is it applied?
Mix Part A and Part B at 79:21 by weight with a slow-speed stirrer, roller- or brush-apply within the ~25-minute pot life, then broadcast sand where a mechanical key is needed.
About Sika Sikalastic-10 Primer EP
Sikalastic-10 Primer EP is the preparation coat that decides whether a waterproofing system lasts a decade or fails in a monsoon. It is a two-component epoxy built on epoxy resin with special fillers, supplied at 100% solids and completely free of solvent, which keeps odour low enough to use in enclosed plant rooms, basements and occupied buildings. Because it carries no solvent, there is no shrinkage as it cures and no risk of solvent entrapment beneath the membrane laid on top. The formulation is deliberately thin so it wets out and penetrates low-to-medium absorbency substrates rather than sitting as a film on the surface.
For a distributor-and-applicator audience in India, the value of this primer is practical rather than glamorous. Roof decks here are rarely perfect: they carry laitance, fine dust, curing-compound residue and variable moisture. A membrane bonded straight to that surface has no real anchor. Sikalastic-10 Primer EP soaks into the top few millimetres of the slab, binds the loose fines together and hardens into a rigid, well-keyed base. It works over concrete, cement screeds, epoxy mortars and even metal decks, and doubles as the binder for scratch coats, levelling layers and small repair mortars, so a single pail often covers several tasks on the same site.
The technical insight
The primer earns its place through penetration, not thickness. Adhesion between a membrane and concrete fails at the weakest link, and on an untreated deck that link is the loose, dusty, friable skin of laitance sitting on the surface. A high-viscosity coating bridges over that skin and takes it with it when the membrane peels. Sikalastic-10 Primer EP is formulated at low viscosity precisely so it flows past the surface and impregnates the pore structure below the laitance. The epoxy then cures inside those pores, effectively stitching the weak layer to sound concrete underneath and converting a dusty face into a hard, dimensionally stable substrate. That is why the tensile adhesion result reads as “concrete failure” above 1.5 N/mm2 (EN 1542): the bond is stronger than the concrete itself, so any theoretical failure would tear the slab rather than the interface. A Shore D hardness of about 76 after seven days (ASTM D2240) confirms the cured film is rigid enough to carry the membrane and light traffic without deforming.
Where it is used
- Priming concrete roof decks and podiums before Sikalastic liquid-applied membranes
- Surface conditioning of cement screeds and topping slabs prior to waterproofing
- Priming under SikaShield bituminous (torch- and self-adhesive) membrane systems
- Priming metal decks and flashings, with sand broadcast for a mechanical key
- Acting as the binder resin for scratch coats and thin repair mortars
- Levelling-layer binder to true up minor undulations before membrane application
- Stabilising and dust-proofing weak, friable cementitious surfaces
- Priming epoxy mortar substrates that will receive a subsequent Sika coating
Key advantages
- Solvent-free, 100% solids formula with very low odour, suitable for enclosed and occupied areas
- Low viscosity gives deep penetration and excellent substrate anchorage
- Develops concrete-failure adhesion above 1.5 N/mm2 (EN 1542)
- Multi-substrate: bonds to concrete, screed, epoxy mortar and metal
- Doubles as a binder for scratch coats, levelling layers and repair mortars
- Short waiting times keep the membrane installation moving on site
- No solvent means no shrinkage, no entrapment and no fire-risk vapours
- Compatible across the Sikalastic and SikaShield membrane families
Limitations & considerations
- Short pot life of about 25 minutes at +20C means only mix what the crew can apply quickly
- Two-part epoxy demands accurate 79:21 by-weight mixing; site guesswork weakens the film
- Substrate moisture must be at or below 4% by weight and RH at or below 80%, so damp or green slabs need drying first
- Application window is +8C to +35C for both ambient and substrate; outside this the cure is compromised
- Not a waterproofing layer in itself, it is only the primer beneath the membrane
- On metal and where a mechanical key is needed, sand must be broadcast while the film is still wet
Selection & best practice
Start with a sound, clean substrate: remove laitance, curing compounds, oil and loose material by grinding or shot-blasting, then vacuum off all dust. Confirm the surface is at or below 4% moisture and at least 3C above the dew point to avoid condensation and blooming during cure. Combine the full unit at the fixed 79:21 by-weight ratio and mix with a slow-speed drill (roughly 300-400 rpm) for two to three minutes, scraping the sides so no unmixed resin remains. Decant and re-stir briefly to avoid resin left clinging to the pail. Apply by brush or roller in one even coat, working within the ~25-minute pot life at +20C; expect that window to shorten in Indian summer heat, so mix smaller batches. Where a mechanical key is required, especially on metal or for a levelling layer, broadcast clean, dry quartz sand into the wet primer. Overcoat with the chosen Sikalastic or SikaShield membrane within the recommended window while the primer is still slightly tacky for the best inter-coat bond.
Specifications
| Chemistry | Two-component, 100% solids, solvent-free epoxy resin with special fillers |
| Mixing ratio | Part A : Part B = 79 : 21 by weight |
| Pot life | Approx. 25 minutes at +20C |
| Shore D hardness | Approx. 76 after 7 days at +27C (ASTM D2240) |
| Tensile adhesion strength | >1.5 N/mm2, concrete failure (EN 1542) |
| Consumption (cementitious) | 0.30-0.50 kg/m2 as primer |
| Consumption (metal) | 0.20-0.25 kg/m2 |
| Consumption (levelling layer) | 1.0-1.2 kg/m2 |
| Pack size | 20 kg unit (Part A 15.8 kg + Part B 4.2 kg) |
Industry use cases
Commercial roofing
Priming large concrete roof decks on malls, offices and IT parks before a Sikalastic liquid-applied membrane, ensuring the system bonds across dusty, wide-area slabs.
Industrial and warehouse
Conditioning metal decks and cement screeds in factory and logistics roofs, with sand broadcast to key the surface for bituminous SikaShield systems.
Basements and water tanks
Low-odour, solvent-free priming in enclosed below-grade areas where solvented primers are impractical, ahead of Sika waterproofing coats.
Repair and refurbishment
Stabilising weathered, friable terrace slabs during re-waterproofing works, and acting as the binder for patch repair mortars in the same operation.
Podium and landscape decks
Priming podium slabs and planter decks before membrane installation, giving the concrete-failure adhesion these long-service, buried systems demand.
Frequently asked questions
Is Sikalastic-10 Primer EP a waterproofing coating on its own?
What substrates can it be applied to?
How much primer will I need per square metre?
What is the pot life and how should the two parts be mixed?
What surface and weather conditions are required?
Does Space Arc supply this across India?
How we position Sika Sikalastic-10 Primer EP
Sikalastic-10 Primer EP is the entry point to a full Sika roofing system, so specify it alongside the membranes it feeds: Sikalastic liquid-applied membranes for cold, seamless waterproofing, and SikaShield bituminous membranes where a torch- or self-adhesive sheet is preferred. Where a mechanical key is required, pair it with clean quartz sand for broadcast. For structural repairs on the same deck, the Sika MonoTop and Sikadur ranges complete the substrate before priming. If a project is specified around Fosroc, a genuine counterpart exists in Fosroc Nitoprime 25, a solvent-based modified epoxy primer that keys concrete for Nitoflor toppings, Nitocote coatings and Nitomortar repairs. Space Arc carries both families and will match the primer to whichever membrane or coating system the consultant has approved.
Fosroc Nitoprime 25 — A specifier standardised on the Fosroc system, or working over a slightly damp slab, may prefer Nitoprime 25 as the epoxy primer keying concrete for Fosroc floor toppings, coatings and repairs.
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