The word “anti-slip” on the box means nothing if there isn’t a number after it. Here’s why.
Every year in Spain, thousands of accidents occur from slipping in the bathroom. And many of them happen on shower trays that, according to the label, are “anti-slip”. The problem isn’t that the label lies exactly. The problem is that “anti-slip” isn’t an official classification. It’s a marketing word. And there’s an enormous difference between a tray with a C1 rating (which can technically call itself “anti-slip”) and one with a C3 rating (which genuinely doesn’t slip).
If you’re thinking about renovating your bathroom or simply changing the shower tray, you need to understand what these numbers mean. Because your family’s safety depends on something as apparently dull as a technical standard.
Don’t worry, we’ll make it understandable. Without unnecessary jargon, but with the data you need to make an informed decision.
What the regulations say (and why it matters)
In Spain, the slip resistance of floors and shower trays is regulated by two main frameworks:
The Technical Building Code (CTE)
The Technical Building Code, in its basic document DB-SUA (Safety in Use and Accessibility), establishes minimum slip-resistance requirements for floors based on their use and location.
In the CTE regulations, article 13.4 of DB-SUA specifies class 2 for wet areas where people walk barefoot — and that includes shower trays. This isn’t a recommendation: it’s a legal requirement for new builds and renovations that require a technical project.
The UNE-EN 14411 standard and the DIN 51097 test
The anti-slip classification for bare feet is determined by testing according to the DIN 51097 standard (a German standard adopted as the reference across Europe). The test is simple: a person walks barefoot on the wet surface as it’s progressively tilted, and the angle at which they start to slip is recorded.
The results are classified into three levels:
| Class | Inclination angle | Grip level | Recommended use |
|---|---|---|---|
| A (C1) | 12°–17° | Low | Dry changing rooms, walkways with wet footwear |
| B (C2) | 18°–23° | Medium | Showers, pools, areas walked barefoot with water |
| C (C3) | 24°+ | High | Pool ramps, high-security showers, care homes |
The equivalence between the letters A/B/C (DIN standard) and the numbers C1/C2/C3 varies by laboratory and manufacturer, but in practice they’re used interchangeably. What matters is the inclination angle it can withstand without slipping.
Legal minimum for shower trays in Spain: class B (C2).
That’s what the CTE requires. However — and here’s the important part — there are shower trays on the market sold as “anti-slip” that only meet class A (C1). They legally shouldn’t be installed in a new-build shower, but they’re sold, installed and nobody inspects them.
The “anti-slip” trap without a classification
This is where the industry plays with ambiguity. When a manufacturer puts “anti-slip surface” on a shower tray’s data sheet without specifying the class, they’re not telling you anything useful. It’s like saying a car is “fast” without saying what speed it reaches.
We’ve seen shower trays sold in big-box stores with a sticker saying “anti-slip” in large letters and, in the fine print of the data sheet (if it even has one), a C1 classification. A C1 tray when wet with soap and bare feet is slippery. Not as much as a polished floor, but enough that someone with compromised balance — an elderly person, a pregnant woman, a child — could fall.
Our recommendation is emphatic: never trust the word “anti-slip” without seeing the classification number. Ask for the technical data sheet. Look for the reference to the DIN 51097 test or the UNE-ENV 12633 standard. If the manufacturer doesn’t provide that information, be sceptical.
This isn’t being paranoid. It’s being responsible. The Spanish ceramic manufacturers’ association ASCER publishes guides on anti-slip classification that confirm the importance of verifying these data before buying.
Which materials are naturally more anti-slip
Not all shower tray materials behave the same when wet and soapy. The surface texture and material composition largely determine grip.
Mineral resin: the best all-round option
Mineral resin trays (such as Roca’s Stonex or formulations by McBath and Fiora) have a micro-granulated surface texture that provides very good natural grip. Most mid-to-high-range resin trays meet C3 from the factory, without needing additional treatments.
Grip advantages:
- Consistent surface texture that doesn’t wear away with normal use.
- The anti-slip finish is part of the material itself, not an applied layer that can deteriorate.
- Pleasant barefoot feel (not cold, not rough).
Ceramic and porcelain: depends on the finish
A ceramic or porcelain shower tray can be highly anti-slip or not at all. It all depends on the surface finish:
- Natural/matt finish: usually meets C1–C2. Fine for walls, borderline for shower use.
- Grip or textured finish: meets C2–C3. The correct choice if you want ceramic on the shower floor.
- Polished/glossy finish: class A or lower. Slippery when wet. Never for a shower.
Natural stone: a gamble
Natural stone (marble, granite, slate) has grip that varies enormously depending on the stone type and finish. Natural unpolished slate can be very anti-slip (C2–C3). Polished marble is an ice rink the moment it gets wet. Bush-hammered granite (with a hammered texture) offers C2 in most cases.
The problem with natural stone is that it wears with use and cleaning, and its grip can decrease over the years. Additionally, porous stone (like travertine or limestone) absorbs water and soap, creating other problems.
Acrylic: the most slippery
Budget acrylic trays perform the worst. Their smooth, non-porous surface has very little grip when wet. “Anti-slip” acrylic models usually have a granular coating that improves grip, but that coating wears away with use and aggressive cleaning products. In 3–4 years, an “anti-slip” acrylic tray may have lost much of its grip capability.
Comparison table: materials and real classification
| Material | Typical classification | Anti-slip durability | Barefoot feel | Indicative price |
|---|---|---|---|---|
| Mineral resin (Stonex, etc.) | C2–C3 | Excellent (permanent) | Warm, pleasant | €140–250 |
| Porcelain grip | C2–C3 | Very good (10+ years) | Cool, textured | €120–300 |
| Standard ceramic | C1 (max C2) | Good if not polished | Cold | €80–150 |
| Textured natural stone | C2 (variable) | Medium (wears down) | Variable | €250–600 |
| Basic acrylic | C1 | Poor (wears in 3–4 years) | Tepid, too smooth | €80–150 |
| Acrylic with coating | C1–C2 | Poor (coating degrades) | Tepid, artificial texture | €100–180 |
More details on each material in our shower tray comparison: resin vs ceramic vs stone.
How the anti-slip test is done
To help you understand where these numbers come from, it’s worth briefly explaining how the testing works.
The DIN 51097 test works as follows:
- A sample of the material is placed on a platform that can be gradually tilted.
- The surface is wetted with water and a standardised soapy solution.
- A barefoot person walks on the surface while the platform is progressively inclined.
- The maximum angle at which the person can walk without slipping is recorded.
Certified laboratories perform this test with multiple subjects to obtain a statistically valid average. The result is classified into categories A, B or C according to the table we’ve seen.
There’s also a test for footwear (standard UNE-ENV 12633, equivalent to DIN 51130), which classifies from R9 to R13. This is used for industrial floors, commercial kitchens, etc. For domestic showers, the correct reference is always the A/B/C classification (bare feet), not R9–R13 (footwear).
If a manufacturer only gives you the R classification (for example, “R10”) for a domestic shower tray, they’re using the wrong standard. R10 for footwear doesn’t necessarily equate to C2 for bare feet. They are different tests.
What the CTE requires and what we recommend
The CTE DB-SUA requires class 2 (equivalent to B or C2) as a minimum for areas where people walk barefoot in the presence of water. That covers showers.
We recommend class 3 (C or C3) whenever possible, especially if:
- There are elderly people in the home.
- There are small children.
- It’s a high-use bathroom (large family).
- It’s tourist accommodation (added legal liability).
The price difference between a C2 and a C3 tray of the same material is usually under €30. It’s a ridiculously small investment for the safety it provides. If you want to explore bathroom safety further, our guide to preventing falls covers the 8 most effective measures.
How to maintain grip over time
An anti-slip shower tray doesn’t maintain its properties by magic. It needs minimal care.
What degrades anti-slip performance:
- Abrasive cleaning products (bleach on resin, hydrochloric acid, metal scourers).
- Build-up of soap and limescale that fills the surface micro-texture.
- Excessive mechanical wear (dragging heavy objects over the tray).
What preserves anti-slip performance:
- Weekly cleaning with neutral soap and a soft sponge.
- Thorough rinsing to prevent limescale deposits.
- Avoiding acidic or abrasive products.
We have a complete guide on how to clean your shower screen and tray with recommended products and a compatibility table by material.
A relevant fact: mineral resin trays maintain their anti-slip classification throughout their useful life (15–20 years) if properly cared for. Coated acrylic trays lose between 30% and 50% of their grip in the first 5 years of normal use. That’s one of the reasons resin is our standard recommendation.
Walk-in designs and the importance of continuous flooring
Walk-in bathroom designs (open shower with no raised tray, continuous flooring) are increasingly popular. In these designs, the entire shower area floor is porcelain or microcement with a slope towards a linear drain. There’s no “tray” as such — the floor is the tray.
In these cases, the anti-slip classification of the porcelain you choose is even more critical. Because there’s no curb to demarcate the wet zone: water can reach areas where you don’t expect to step on wet surface. The entire bathroom floor should meet C2 as a minimum.
If you’re interested in this type of design, our Walk-In Invisible is an example of how to do it correctly with C3 porcelain across the entire surface.
What to do if you already have a slippery tray
If your current shower tray slips and you don’t want (or can’t) change it right now, there are temporary solutions:
Anti-slip stickers: adhesive strips with abrasive texture that stick to the tray surface. Cost €8–15 per pack. They work well for the first 3–6 months, then lose adhesion and need replacing. Not attractive, but effective short-term.
Shower mat with suction cups: the classic solution. Price: €10–25. It works, but has a serious problem: underneath the mat, moisture and dirt accumulate, breeding mould. You need to lift it after every use and let it dry. If you don’t, you end up with a hygiene problem worse than the safety one.
Liquid anti-slip treatment: products applied to the surface that create a permanent chemical micro-texture. Price: €20–40. They work reasonably well on ceramic and porcelain. On resin and acrylic, results are less predictable. Reapplication every 1–2 years is needed.
The real solution: change the tray. If your current tray is a smooth acrylic rated C1 or lower, no temporary solution matches the safety of a C3 resin tray. And changing a shower tray isn’t a full renovation — a competent plumber does it in half a day. Calculate here what it would cost in your case.
Frequently asked questions
Is a C3 shower tray uncomfortable to stand on?
No. The texture of a C3 resin tray is a fine micro-granulate that feels like standing on compacted sand — firm grip but soft touch. It’s not like walking on sandpaper. People who try a C3 resin tray for the first time are usually surprised by how pleasant it feels. Our premium vs budget materials designs compare the feel of each finish.
Can I find out the classification of my current tray?
If you still have the receipt or the manufacturer’s data sheet, it should be listed there. If not, search for the model and brand on the manufacturer’s website — most publish technical data sheets with the classification. If you can’t find the information, do the home test: wet the tray, add soap, and step carefully. If you feel your foot sliding even slightly, it’s probably C1 or lower.
Do shower trays lose grip over time?
It depends on the material. Mineral resin trays maintain their classification throughout their useful life. Textured porcelain also holds up very well. Acrylic with surface treatment loses significant grip in 3–5 years. Natural stone wears progressively and can lose a class (from C2 to C1) in 8–10 years if not maintained.
Is C2 mandatory for a shower tray in a renovation?
If the renovation requires a technical project (full renovation with layout change, for example), yes — the CTE requires C2 as a minimum in wet areas where people walk barefoot. If it’s a direct tray replacement without a technical project, there’s legally no inspection, but the safety recommendation is the same. We install C2 or C3 every time, without exception. It’s a matter of professional responsibility.
Does the shower screen’s EasyClean treatment affect the tray’s anti-slip performance?
No. The EasyClean anti-limescale treatment is applied to the screen glass, not to the tray. They’re different surfaces with different treatments. EasyClean is hydrophobic (repels water), which is the opposite of what you need on a shower floor (you need the foot to grip). Don’t confuse the two concepts.
Safety is non-negotiable (and doesn’t cost more)
Let’s close with something we consider fundamental. Choosing a safe shower tray doesn’t cost more than choosing one that slips. The price difference between a C1 acrylic tray at €90 and a C3 resin tray at €160 is €70. Seventy euros. That’s the cost of dinner for two.
Those €70 can be the difference between a normal shower on a Tuesday morning and a fall that ends in A&E. It’s not dramatic to put it that way — it’s the reality we see every time someone calls us for an urgent renovation after a slip.
When you request a quote for your renovation — from us or from anyone — insist on knowing the anti-slip classification of the tray they’re proposing. Don’t accept a “yes, it’s anti-slip” without seeing the data sheet. Ask for the number. If it’s C2 or C3, go ahead. If it’s C1, ask them to change it. And if they can’t tell you the classification, find another company.
At Reformarte we install C2 or C3 shower trays in every single renovation. It’s a policy we don’t negotiate. Because the safety of the people who will use that bathroom doesn’t depend only on them — it also depends on whoever built their shower.
If you want a quote to change your shower tray or renovate the entire bathroom with materials that truly meet the regulations, calculate here or contact us directly.
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