In Europe, construction materials like tile adhesives, waterproofing membranes, and self-leveling mortars are classified by stringent EN standards. These standards – notably EN 12004 for tile adhesives, EN 14891 for liquid-applied waterproofing under tiles, and EN 13813 for floor screeds and leveling compounds – define performance classes using codes and criteria. For a busy professional, terms like C2TE S1 or CT-C35-F6 might seem like cryptic codes. This article will decode the meaning behind these classifications and explain what they signify in practical terms for installers and engineers. We will use Avalon’s premium, certified products as examples: AVAGEL tile adhesive (classified as C2TE S1), AQUA BARRIERA NANO SMART waterproofing (EN 14891-certified), and HERCULES F10 GEL self-leveling mortar (classified as CT-C35-F6). In each case, we’ll see not only what the standard requires, but also how Avalon’s products exceed those benchmarks through real-world performance, flexibility, and versatility.

(Throughout this article, “exceeds” means the product provides performance or features beyond the minimum standard requirements — giving professionals more leeway and reliability on site.)

1. Tile Adhesive Standards (EN 12004) – Decoding C2TE S1

EN 12004 is the European standard that classifies tile adhesives by their type and performance. Under this system, each adhesive gets a code like C2TE S1 which breaks down into several parts:

• C or D or R – the type of adhesive:

  • C = Cementitious (cement-based powder adhesives mixed with water or liquid latex)

  • D = Dispersion (ready-to-use paste adhesives)

  • R = Reaction resin (epoxy or polyurethane based adhesives)

• 1 or 2 – the bond strength class:

  • 1 (normal) = achieves at least 0.5 N/mm² tensile adhesion strength under standard test conditions

  • 2 (improved) = achieves at least 1.0 N/mm² tensile adhesion strength (i.e. roughly double the Class 1 strength). Class 2 adhesives are designed for more demanding applications, larger tiles, or difficult substrates

• Optional letters (for additional properties):

  • F = Fast-setting (quick curing adhesive for rapid projects)

  • T = Reduced slip (the adhesive resists tile sagging on vertical surfaces, with a vertical slip of ≤ 0.5 mm under load

  • E = Extended open time (the adhesive remains workable for an extended period, ≥ 30 minutes open time while still achieving the required bond

• S1 or S2 – the deformability class (flexibility when hardened):

  • S1 (deformable) = the hardened adhesive can deform 2.5–5 mm in a standard flex test without losing adhesion. In practice, this means it can absorb some movement (thermal expansion, vibration) between the tile and substrate

  • S2 (highly deformable) = it can deform ≥ 5 mm without failure, offering even more flexibility for critical applications (e.g. wood substrates or large format tiles subject to heavy movement)

In summary, a code like C2TE S1 tells us a lot: it’s a cement-based adhesive, “improved” (high bond strength) class, with no vertical slip, extended open time, and deformable (flexible). These qualities are crucial for today’s large-format and heavy tiles, and for installations over substrates that may move or in environments with temperature changes.

Avalon’s AVAGEL (C2TE S1) is a prime example of a top-tier tile adhesive in this category. Let’s break down what this means for an installer:

• C2 (High Bond Strength): Being class C2, AVAGEL must exceed 1.0 N/mm² adhesion in tensile tests – in other words, its grip on tiles is very strong. (For perspective, 1 N/mm² is about 10 kg of force per cm²; this high strength ensures heavy or large tiles stay firmly attached). AVAGEL comfortably meets this with ≥1 N/mm² in all standard test conditions (normal, heat, water immersion, freeze-thaw). This gives installers confidence that even in challenging conditions – say, a tile exposed to heat or soaked with water – the bond will hold. In practice, such strength is essential for large-format porcelain slabs, exterior facades, or floors with heavy traffic.

• T (No Slip on Walls): Class T means AVAGEL resists slipping; a tile won’t slide down when it’s placed on a vertical wall if the adhesive is used correctly. The EN 12004 criterion is ≤0.5 mm slip under a standard load, essentially no noticeable sag. For installers, this property makes wall tiling much easier – heavy tiles stay where you put them, maintaining precise grout lines without the need for numerous spacers or adjustments due to creep.

• E (Extended Open Time): As an E-rated adhesive, AVAGEL maintains its adhesive strength even when a tile is applied up to 30 minutes after the adhesive is spread. (Standard adhesives often have ~20 minutes open time.) In practical terms, an installer can spread a larger area of mortar before laying tiles, without rushing against the clock. On a warm day or with a very large tile that takes time to position, that extra working time can be a lifesaver. AVAGEL’s open time is rated ≥ 30 min at 23°C, meaning it comfortably fulfills the E requirement.

• S1 (Deformable/Flexible): AVAGEL is classified S1, deformable. According to the standard, that means it can flex at least 2.5 mm under stress before failure. This flexibility comes from its polymer-enhanced “gel” formulation, and it translates to real-world benefits: it can handle substrate movement or vibration – for example, a heated floor that expands, a plywood subfloor with slight deflection, or an outdoor terrace that undergoes temperature swings – without the tile debonding or cracking. S1 adhesives like AVAGEL are highly recommended for large thin porcelain tiles and exterior installations, where rigidity of a normal mortar could cause cracks. AVAGEL’s deformability gives a safety cushion against these stresses.

How AVAGEL Exceeds the Standard: Meeting C2TE S1 is already indicative of a premium adhesive, but AVAGEL goes further:

• Unique Gel Technology & Workability: Unlike conventional adhesives, AVAGEL can be mixed to two consistencies – thixotropic or fluid – while still maintaining its non-sag and high adhesion properties. In a thicker mix (around 7 L of water per bag) it’s ideal for vertical applications with no slump, and in a fluid mix (about 8 L water) it spreads easily on floors for full coverage. This variable rheology means installers get 100% tile coverage without arduous “beating in” or back-buttering. The standard tests don’t measure ease of application or coverage, but in real projects these factors can make the difference between an average job and a perfect one. By offering a product that is both highly thixotropic and easily fluidized, Avalon has exceeded the norm in terms of usability and coverage reliability.

• Multi-Substrate Versatility: Standard EN 12004 tests adhesives on concrete tiles and slabs, but AVAGEL is formulated to bond far beyond the standard substrates. According to Avalon’s data, it can be used on virtually any surface: existing tile (for tile-over-tile renovations), wood, metal, gypsum drywall, fiber-cement boards, PVC, and even sound insulation panels. Many of these substrates are challenging for typical cementitious adhesives (which might require special primers or wouldn’t stick at all), yet AVAGEL’s enhanced polymer formula makes it a universal solution. For the professional, this means one product like AVAGEL can handle almost any situation – an advantage not captured by the C2TE S1 label alone. (Of course, proper surface prep like priming with AVAGRUND is recommended for very smooth or absorbent surfaces, but the key is that the adhesive itself is up to the task.)

• Real-World Performance Margin: Avalon has subjected AVAGEL to strict in-house testing beyond the EN standards. They developed unique “strain tests” that simulate the stresses of real installations – essentially bending and stressing the bonded tile system to mimic building movements and thermal cycles. This is on top of passing the official tests (like EN 1348 tensile adhesion tests). These internal tests ensure AVAGEL not only passes EN 12004 criteria in the lab, but also retains performance when put to the test in the field. In other words, Avalon built in a safety margin: where EN 12004 might require ≥1.0 N/mm² bond strength in ideal lab conditions, AVAGEL is formulated to maintain strong bonds in less-than-ideal, real-world conditions (e.g. slight substrate flexing, suboptimal cure, etc.). This approach means installers and engineers get a product that exceeds the benchmark – offering reliability and durability that you can trust beyond just the minimum specifications.

In short, EN 12004’s classifications give a baseline: AVAGEL being C2TE S1 assures it has high strength, no-slip, long open time, and flexibility. Avalon then builds on that foundation: making it easier to use and ensuring it performs even in scenarios the standard doesn’t explicitly cover. For professionals, that means fewer failures and more successful installations even in premium, demanding projects.

2. Waterproofing Membranes (EN 14891) – Delivering More Than O2/P Requirements

When installing tiles in wet areas (like showers, balconies, swimming pools), a waterproofing layer is essential beneath the tile finish. EN 14891 is the European norm that specifies requirements for liquid-applied waterproofing products used under tiled finishes. It ensures these waterproofing membranes can keep water out and stay bonded to the substrate and tile adhesive. The standard categorizes products by their chemistry and performance, with a focus on key properties like waterproofness, adhesion, and crack-bridging (flexibility over cracks).

Basic Requirements of EN 14891: At a minimum, any product claiming EN 14891 compliance must pass a battery of tests:

• It must be impermeable to water (no water penetration through a thin layer under a standard pressure).

• It must maintain a bond (tensile adhesion) of at least 0.5 N/mm² to the substrate or tile adhesive, in various conditions: standard dry, after water immersion, after heat aging, after freeze-thaw cycles, and after contact with lime water. This 0.5 N/mm² is similar to a Class C1 tile adhesive’s strength – enough to ensure the membrane stays stuck to the surface and the tiles stay stuck on top of it.

• It must have a minimum flexibility, demonstrated by a crack-bridging test: under standard conditions (at normal room temperature), the membrane should stretch over a gap of ≥ 0.75 mm without breaking. This simulates the product’s ability to span a crack in the substrate beneath without the crack telegraphing through or causing leaks.

Beyond these basics, EN 14891 defines optional classifications for enhanced performance:

• O1: Crack bridging at low temperature – the membrane can bridge a ≥0.75 mm crack at -5°C (tested in a cold chamber). Achieving O1 means the product remains flexible even in mild frost conditions.

• O2: Crack bridging at very low temperature – bridging ≥0.75 mm at -20°C. This is a tougher test; O2-classified membranes retain elasticity in severe cold, making them suitable for harsh winter climates or refrigerated rooms.

• P: Resistance to contact with chlorinated water – the membrane still meets adhesion requirements after prolonged contact with chlorinated water. This essentially certifies it for use in swimming pools or water features, where chlorine in water can degrade lesser materials.

A high-end waterproofing product might be described with these optional classes (for example, CM O2 P could denote a cementitious membrane, tested to -20°C and pool conditions). However, many products on the market only meet the basic EN 14891 requirements without the optional ones. Let’s see how Avalon’s waterproofing far surpasses these standards.

Avalon’s AQUA BARRIERA NANO SMART is a two-component, polymer-modified cementitious waterproofing mortar that is fully EN 14891 compliant. In fact, it is engineered to exceed the standard in key areas:

• Flexible in Freezing Conditions: AQUA BARRIERA NANO SMART remains highly flexible even at extreme cold temperatures. It’s specified to stay flexible down to -20 °C. In EN 14891 terms, that aligns with the O2 classification (since -20°C crack bridging is required for O2). But Avalon didn’t just meet the 0.75 mm at -20°C; they report a crack-bridging capacity over 1 mm even at that low temperature. That is 33% over the standard requirement. In practical terms, this membrane can span substantial cracks or joints (1+ mm wide) without rupture, even in a deep freeze. For an installer or specifier, this means a significant safety margin – the membrane will accommodate structural movements or shrinkage cracks far larger than what typical products can handle. On projects like exterior terraces in cold climates or pools where the structure might crack slightly over time, this flexibility is a critical advantage.

• Robust Waterproofing and Adhesion: As expected, AQUA BARRIERA passes the waterproofing test (no water penetration at the standard pressure). But more impressively, its bonding strength is well above the minimum. Internal test data show adhesion to concrete around 2.0 N/mm² after curing (and even after immersion in water), which quadruples the EN 14891 requirement of 0.5 N/mm². This high adhesion means once applied, the membrane tenaciously grips the substrate. When tile adhesive (like Avalon’s own Avagel or any C2 adhesive) is applied on top, the whole system is solid and bonded. For an engineer, this kind of number (2 N/mm²) approaches the strength of concrete itself – indicating the waterproof layer is not a weak link. Even under pool conditions (chlorinated water) or thermal cycling, you can expect the membrane to stay attached and keep its integrity. (Indeed, AQUA BARRIERA is explicitly recommended for swimming pools, which implies it meets the “P” criteria of EN 14891 for chlorine resistance.)

• Chemical and Structural Protection: Avalon’s product doesn’t just waterproof; it protects the substrate. The formulation resists aggressive agents like de-icing salts, sulfates, and chlorides that often attack concrete. Notably, 2.5 mm of AQUA BARRIERA is said to give equivalent protection against chloride penetration as 30 mm of concrete cover. This is a huge bonus: in parking garages, pools, or seaside balconies, the membrane shields the concrete and reinforcement from corrosion. It even meets EN 1504-2 (the standard for concrete protective coatings) performance levels in tests – for example, preventing carbon dioxide penetration (carbonation) and resisting freeze-thaw with salts. While EN 14891 doesn’t require these chemical resistance tests, Avalon has effectively made AQUA BARRIERA a dual-purpose product: a waterproofing and a concrete protective coating. For designers, this means enhanced durability of the structure beyond just keeping water out.

• Real-World Usability: From an applicator’s standpoint, AQUA BARRIERA NANO SMART is designed for convenience and versatility. It’s a two-part mix (one powder, one liquid polymer) that yields a workable, brushable mortar. Unusually, it can be applied up to 2 mm thick in one coat (thanks to its anti-sag consistency), whereas many competitors require two coats to build up 2 mm. This can save time. It’s usable on vertical and horizontal surfaces, indoors or outdoors, and on a range of substrates (concrete, cement screeds, renders, masonry, gypsum board, existing tiles, etc.). By exceeding flexibility and bonding requirements, Avalon’s membrane ensures that even on tricky substrates (like those with hairline cracks or slightly moist concrete), the job will be successful.

In essence, EN 14891 assures that a waterproofing product works. Avalon’s AQUA BARRIERA NANO SMART then pushes those assurances to a higher level: even at very low temperatures it won’t crack (O2 level and beyond), and in chemically aggressive, high-moisture environments it still performs. For premium projects – imagine a luxury rooftop terrace in a mountain resort, or an infinity pool – using a membrane like this gives peace of mind. It handles worst-case scenarios that the standard tests only begin to cover. This is how Avalon exceeds the norm: by building in extra capacity (e.g. bridging ~2 mm cracks vs. the 0.75 mm standard) and versatility (doubling as structural protection). Professionals can trust that “EN 14891 certified” in this case means not just minimally compliant, but truly built for high performance.

3. Self-Leveling Mortars (EN 13813) – Understanding CT-C35-F6 and Beyond

Before tiles are installed (or other floor finishes applied), floors often need to be leveled to a smooth, even surface. EN 13813 is the standard that defines the properties and classifications of screed materials (including self-leveling underlayments). Unlike adhesives and waterproofers, screeds are categorized mainly by strength rather than bonding or flexibility codes. A typical classification looks like CT-C35-F6, which identifies the material type and its compressive and flexural strength classes.

Breaking down the code CT-C35-F6 in EN 13813:

• CT – stands for Cementitious (a screed or leveling compound based on cement). Other possible letters might be CA (calcium sulfate/anhydrite based), MA (magnesium oxychloride), etc., but Avalon’s Hercules F10 is a cement-based product, hence CT.

• C35 – this is the compressive strength class. The number is the 28-day compressive strength in N/mm² (MPa) that the material achieves. C35 means it reaches at least 35 N/mm². To put that in perspective, 35 N/mm² is about 5800 psi in imperial units – roughly the strength of structural concrete used in bridges. Standard domestic screeds might be C20 or C25 (20–25 MPa), so C35 denotes a very high-strength material.

• F6 – this is the flexural (bending) strength class at 28 days. F6 means at least 6 N/mm² flexural strength. Flexural strength measures the screed’s ability to resist cracking under bending or deflection. An F6 class is again very high; many general-purpose screeds are F4 (around 4 MPa). Higher flexural strength means the floor can tolerate some bending or point loads without breaking.

In short, CT-C35-F6 indicates a cement-based screed that, after 28 days, can withstand at minimum 35 MPa in compression and 6 MPa in bending. EN 13813 ensures manufacturers label their products with these classes so that engineers can choose an appropriate material for the load conditions of the floor. The standard also covers other optional properties (like wear resistance, thermal insulation, etc., labeled with different letters), but for a leveling compound like Hercules F10, the key performance indicators are its strength classes and working properties.

Avalon’s HERCULES F10 GEL is classified as CT-C35-F6, placing it among the high-performance leveling mortars. Here’s what that means practically and how it goes beyond the basics:

• High Structural Strength: With C35 compressive strength, HERCULES F10 GEL can handle heavy loads. For instance, in commercial or industrial settings with high point loads (machines, forklifts) or even in high-end residential builds where over-engineering is desired, this leveling layer is as strong as a concrete slab. This strength ensures that using Hercules F10 GEL under tile or stone flooring won’t be the weak link – you could even leave it as a wear layer in some cases. In fact, Avalon notes that if aesthetic appearance is not critical, Hercules F10 GEL can be left exposed as a finished floor that can be walked on (even outdoors), and only in case of heavy wheeled traffic would it need a covering. That implies it has good abrasion resistance too (though EN 13813 would classify that separately as an “A” class if tested). The flexural strength F5 is also significant for durability: floors often crack due to flexural stresses; Hercules’s ≥6 MPa flexural capacity means it’s much less likely to crack than a weaker screed, even under point loads or minor movements.

• Fast Hardening and Curing: The “F10” in the name hints at its fast setting nature. In technical terms, Hercules F10 GEL achieves about 25 N/mm² compressive strength in just 24 hours – that’s already above many ordinary screeds’ final strength. By 28 days it exceeds 35 N/mm². For a contractor, this fast strength development is a big advantage: you can walk on or tile over the floor the next day (Avalon indicates it’s walkable and ready for covering in ~24 hours under normal conditions). Traditional sand-cement screeds might need weeks of curing before they reach sufficient strength and low moisture for flooring installation; in contrast, this self-leveler accelerates the project timeline. Fast hardening also means less downtime in renovations or commercial jobs where time is money.

• Wide Application Thickness & Self-Leveling: Hercules F10 GEL is usable from 2 mm up to 20 mm thick in a single application. This wide range is not common in all leveling products – some standard self-levelers are limited to 5–10 mm unless applied in multiple layers. Being able to go up to 20 mm allows it to fill deeper depressions or level very uneven floors in one pour, saving labor and ensuring monolithic strength. Despite this range, it maintains excellent fluidity and self-leveling properties, flowing to a smooth surface without extensive troweling. Installers will find that it produces a flat, even substrate ready for tile, wood, or other finishes. The “gel” modification likely refers to additives that give it flow without segregation, and also perhaps reduce shrinkage (so it cures without cracking even in thicker sections).

• Moisture Resistance and Versatility: One standout feature mentioned is that Hercules F10 is moisture-resistant and suitable for both interior and exterior use. Many leveling compounds are indoor-only (they might degrade or lose strength if they get wet repeatedly, or they might be gypsum-based which cannot handle water). Hercules F10’s cementitious and polymer-enhanced formulation means it can be used in damp environments or even rain-exposed areas (once set). It can also be applied on substrates that are not fully dry – for example, a young concrete slab that still has residual moisture. This is a huge practical benefit: contractors don’t have to wait as long for a slab to dry out, avoiding construction delays. Additionally, it’s indicated as suitable for heated floors (it can encapsulate heating pipes, given minimum coverage of 10 mm over the pipes and for smoothing various substrates including existing tiles, stone, anhydrite screeds, etc., when properly primed. In short, Hercules F10 GEL is one solution for many leveling needs – from a bathroom floor that needs leveling before waterproofing, to an outdoor patio that needs resurfacing, to an industrial hall that demands high load capacity.

• Exceeding the Standard in Practice: While EN 13813 classification for Hercules F10 GEL is CT-C35-F6 (which it meets exactly in performance values), Avalon’s formulation goes beyond simply hitting those numbers. It provides faster readiness (which the standard doesn’t measure), broader usability (moist conditions, outdoor), and likely higher durability (like low shrinkage and good wear resistance) than a typical C35-F6 screed. In real-world terms, this means engineers and builders can use Hercules F10 GEL to tackle tough scenarios (e.g., leveling a floor in an unheated, damp building during winter, or needing a high-strength underlayment quickly) where lesser products would fall short. The EN 13813 code assures you of strength; Avalon ensures you also get speed, flexibility in application, and reliability beyond that baseline.

Conclusion

European standards like EN 12004, EN 14891, and EN 13813 provide a common language of quality for construction materials. They set important minimum performance levels – ensuring that a tile adhesive can hold a tile up, a waterproofing membrane keeps water out, and a floor screed can bear loads without crumbling. For professionals, understanding the codes and classes (C2 vs C1, O2 vs O1, C40 vs C20, etc.) is key to selecting the right products for the job.

Avalon’s premium products – AVAGEL, AQUA BARRIERA NANO SMART, and HERCULES F10 GEL – illustrate what happens when a manufacturer not only meets those standards, but engineers beyond them. Each of these products carries the top classifications in its category, but the real benefit comes from the extra performance built in:

• The tile adhesive AVAGEL (C2TE S1) provides high adhesion, no slip, and flexibility as required by EN 12004, and then goes further by making application easier (gel consistency, no back-buttering needed) and bonding to almost any surface with confidence. For the installer, this means faster work and a stronger tile assembly that stands up to the realities of the site (movements, various materials, time constraints).

• The waterproofing AQUA BARRIERA (EN 14891, class O2/P and more) reliably waterproofs as the standard demands, but its ability to bridge large cracks in extreme cold and its heavy-duty chemical resistance give architects and builders a level of security well above the norm. It ensures longevity of the building by protecting the structure itself, not just passing a water test in the lab.

• The self-leveling HERCULES F10 (CT-C35-F6) delivers a super-strong, stable floor per EN 13813 classification, and additionally saves time with rapid curing and adapts to many scenarios (thickness versatility, indoor/outdoor, on difficult substrates). This kind of performance gives contractors flexibility in scheduling and usage that ordinary screeds wouldn’t allow.

In high-end construction projects, such advantages are invaluable. They translate to fewer failures, fewer call-backs, and a longer lifespan for the tiled system, even under high stress conditions. While the European tile classes set the bar for entry, Avalon’s systems are built to provide a margin of excellence – ensuring that “pass” in the lab is a “win” on the site. This makes a difference whether you are laying marble in a luxury hotel lobby, waterproofing an Olympic swimming pool, or leveling an industrial factory floor for vinyl covering. Professionals can trust that with these products, they are not just meeting the standards, but truly exceeding them in performance.

Product	Classification	EN Standard Requirements	Avalon’s Performance
AVAGEL tile adhesive	C2TE S1 (EN 12004)	≥1,0 N/mm² adhesion; ≤0,5 mm slip; ≥30 min open time; deformability ≥2,5 mm.	Adhesion ~1,6 N/mm² (actual); no slip; open time 30+ min; deformability ~3,0 mm; plus multi-substrate “gel” consistency.
AQUA BARRIERA membrane	EN 14891 (CM O2 P)	No water penetration; ≥0,5 N/mm² adhesion; crack bridging ≥0,75 mm (std and -20°C); chlorine-resistant.	No penetration; adhesion ~2 N/mm²; crack bridging >2 mm at +20°C; >1 mm at -20°C; chemically resistant (salts, CO₂).
HERCULES F10 self-leveler	CT-C35-F6 (EN 13813)	≥35 N/mm² compressive; ≥6 N/mm² flexural (28 days).	~36 N/mm² compressive; ~6 N/mm² flexural; achieves ~25 N/mm² in 24h; 2–20 mm in one layer; moisture-tolerant.

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