Materials for flooring — natural stone concrete and tiles

The surface material is what the user sees and treads on — and it determines requirements for the substructure grouting and maintenance. The landscape gardener must know the material's properties so the right solution is matched to load weather and aesthetics.

Concrete paving slabs and paving stones (SF-stones) are the most common materials in Denmark. They are uniform in format and easier to adapt than natural stone. SF-stones are suitable for driveways and traffic areas; concrete slabs for terraces and paths. Colour and surface texture (smooth, sandblasted, ribbed) affect friction — important in sloping terrain.

Granit er ekstremt holdbart og slidstærkt og bruges i dansk anlægsgartneri til klassisk belægning, rendestensforløb og kantsætning. Brosten lægges typisk med 20–25 ‰ fald på grus/råjord-nær opbygning (NfA 1992). Chaussésten (9×9×9 cm) giver et karakteristisk udseende og gode drænmuligheder, men kræver mere nøjagtigt lægningsarbejde og fugesand. Vejledende: chaussésten ≈ 85–95 stk/m² med ~10 mm fuge — lidt lavere end den rene grid-formels ~100 stk/m², fordi uregelmæssige stenmål og buelægning giver spild og bredere fuger.

Brick clinkers are fired clay materials with a rich colour palette. They require a clinker type certified for outdoor use and able to withstand freeze-thaw cycles (brick cladding clinkers are typically documented according to EN 1344, cf. supplier's product data sheet — not a landscape gardening standard). Always check water absorption and frost resistance on the data sheet — a wrong choice results in spalling already the first winter.

Surfacing materials are building materials each with their own harmonised European product standard. Because the standards are harmonised, the stones are CE marked, and the supplier must provide a declaration of performance (DoP) stating the declared characteristics:

Check the DoP at delivery: dimensions and tolerances, strength (split tensile/bending strength), frost-thaw resistance, abrasion resistance and slip resistance. It is the documentation that the stone can do what the project requires — not a sales argument.

In Danish climate, freeze-thaw cycles are the hardest wear. A material that absorbs much water cracks and flakes when the water freezes and expands. Therefore frost and water absorption are documented:

• 01Concrete: frost-thaw resistance (with and without de-icing salt) is documented according to DS/EN 1338 (stone) and DS/EN 1339 (tiles); the supplier states the class in the DoP.
• 02Natural stone: water absorption is determined according to DS/EN 13755 and frost resistance according to DS/EN 12371 — low water absorption usually means good frost resistance.
• 03Brick/tiles: paving tiles for outdoor use are documented according to DS/EN 1344; always select a frost-resistant tile type for paving.

On walkways and traffic areas, friction is a safety property. Slip resistance is typically measured as a USRV-value (Unpolished Slip Resistance Value) with a pendulum apparatus and is included in product standard testing. Smooth, polished surfaces have low friction — pay special attention to ramps, steps and areas that get wet or icy.