Frost
Pools round Troyes, Reims or Chaumont are covered from October to April. The coping stays wet under leaves and snow while the nights drop below zero. Water in the stone freezes, expands by about 9% and pushes the grains apart. After a few winters, porous stone flakes or loses its edges. A stone that's fine on the Côte d'Azur may not last here.
The tests to ask for
Outdoor paving stone in Europe comes under NF EN 1341. Four results matter for a pool.
- Frost resistance, NF EN 12371, freeze-thaw cycles. Ask how many cycles and the result.
- Water absorption, NF EN 13755, the lower the better. Dense granite is usually well under 1%.
- Slip resistance, pendulum test (USRV), NF EN 14231. Wet bare feet need a textured finish.
- Flexural strength, NF EN 12372, which sets the thickness for coping that overhangs the water.
Anyone selling stone into France should have these figures. If they can't give them, treat the stone as untested.
Which stone
| Stone | Frost | Under bare feet | Watch for |
|---|---|---|---|
| Granite, flamed or bush-hammered | Very good when dense | Rough, grips | Hot in full sun if dark |
| Travertine | Depends on the quarry | Soft, cooler | Open holes hold water, buy tested and filled |
| Sandstone | Varies a lot | Grips naturally | Absorbs more, check the figures |
| Dense limestone | Good if tested | Smooth, needs texture | Acid cleaners |
| Polished marble | Not outside | Slippery wet | Avoid |
Profiles, corners and curved ends are on the pool coping page.
Salt pools
Salt water dries in the stone and the crystals do damage much like frost, and the two add up. On a salt pool, go for dense, low-absorption stone, a sealer made for salt, and rinse the coping with fresh water now and then in summer.
Coping
The front is rounded and overhangs the wall by a few centimetres so splashes fall back in. 3 to 5 cm thick is common. The thinner the stone, the more the overhang and the frost result matter. Corners and curves are cut from a template taken on site.
Colour
Black granite on a south-facing terrace in July can be too hot to walk on, even here. Beige travertine, pale sandstone or grey granite stay cooler. The white line left by evaporating pool water also shows far more on dark stone.
Laying
- A fall away from the pool, about 1.5 to 2%.
- A sound, drained base. Water standing under the paving freezes too.
- Movement joints at intervals and against the pool.
- Each coping stone fully bedded in mortar, no gaps for water.
Winter
Keep the water level and floats as the pool installer says, so ice doesn't press on the coping. Clear wet leaves, they stain limestone and travertine. No de-icing salt on the surround.
Our pools
Our travertine pool deck and crazy-paving surround are in the projects. For coping that has to take frost, we'd look at dense granite first. In 2023 our granites were Alaska Gold, Alaska White, Kayrus Grey, Lapidus and Platinium Gold. Whatever you choose, the test results go on the quote. Call +33 7 45 20 76 39, or see terraces and Champagne.
