Slip-Resistant Flooring for Outdoors, Bathrooms and Pools: What R10, R11, R12 and CTE Classes Mean
Quick answer: there are two ways to measure how slippery a floor is. The R scale (R9 to R13), under the DIN 51130 standard, is measured with footwear on a ramp: the higher the number, the more grip. In Spain, the Building Technical Code (CTE, DB SUA 1) uses Classes 1, 2 and 3, measured with the pendulum test. Class 3 is required for outdoor areas, showers and pool edges; Class 2 for bathrooms and kitchens; and Class 1 is enough for dry indoor areas. Since these are different tests, it's worth checking the CTE class listed on each floor's product page.
CTE Slip-Resistance Classes
CTE Class
Resistance (Rd, pendulum test)
Class 0
Rd ≤ 15
Class 1
15 < Rd ≤ 35
Class 2
35 < Rd ≤ 45
Class 3
Rd > 45
Which Class Each Area Needs
Area
Minimum class
Dry indoor areas with a slope under 6%
Class 1
Dry indoor areas with a slope of 6% or more, and stairs
Class 2
Wet indoor areas (bathrooms, kitchens, entrances from outdoors, covered terraces) with a slope under 6%
Class 2
Wet indoor areas with a slope of 6% or more, and stairs
Class 3
Outdoor areas, pools and showers
Class 3
The CTE is mandatory in buildings for public use (hotels, shops, restaurants, schools...). In a private home it isn't mandatory, but it's the best reference for choosing a safe floor.
What Else an Outdoor Floor Needs
Frost resistance: porcelain stoneware (group BIa) absorbs very little water and doesn't break in freezing conditions.
Matte or textured finish: never polished or glossy in areas that get wet.
Slope and joints: a slight slope to drain water, plus expansion joints.
For the pool itself and showers, the porcelain Bellagio 15x15 tile comes in turquoise, beige, grey and graphite. For the pool deck, choose a Class 3 floor from the table above.
Frequently Asked Questions
What slip-resistant floor do I need for a terrace?
A frost-resistant porcelain floor rated CTE Class 3 (or R11-R12), especially if the terrace is uncovered and gets wet from rain.
Is R10 the same as Class 2?
Not exactly. The R scale and the CTE classes are measured with different tests (a ramp with footwear versus a pendulum), so there's no exact equivalence. To meet the CTE, check the class listed on the product page.
What floor should I put around a pool?
A slip-resistant, Class 3 porcelain floor that resists frost and pool-water treatment products. R12 wood-effect versions are very popular for creating a maintenance-free deck.
