Road salt and natural stone
Useful and practical information about the use of road salt on natural stone
The days are shorter, the temperatures below zero. Wrapped up thickly, it goes to the door, the air smells of snow. The floor is frozen, it is raining or snowing – streets and footpaths, but also your own terrace, the balcony made of natural stone or the granite stairs can become smooth. In order to protect yourself and others from falls and the like, it is important to clear sidewalks and e.g. to be treated with road salt. But what about the compatibility of natural stone products and road salt? So that you are well armed in winter and protect your natural stone floor as well as possible, we have put together the most important information and interesting facts about the topic of spreading material and natural stone.
Road salt: not the first choice
When it gets bitterly cold and streets and sidewalks are covered with snow and ice, you can hear them early in the morning: gritters from winter service in action, which generously distribute road salt on the paths. This eliminates the risk of slippery surfaces and reduces the occurrence of accidents. Everyone has to take care of their own sidewalks, stairs, and terrace – and if they are made of natural stone, the question arises whether de-icing salt is the right solution here against slippery surfaces. “I do not recommend treating natural stone with road salt,” says natural stone consultant Adalbert Lange: “In combination with water, the salts can penetrate the stone, which can lead to stains and discoloration”. This applies especially to natural stone types such as limestone, sandstone or travertine. Hard stones such as granite, basalt or quartzite are tough, shine through durability and insensitivity and keep frost and de-icing saltwater out thanks to their stone structure. Nevertheless, if you want to be on the safe side with natural stone, we advise that it is best to avoid road salt on all-natural stone slabs when there is a risk of slippery surfaces and freezing temperatures. This also applies to porcelain stoneware patio slabs – they have a low water absorption capacity and are very robust, but road salt can damage the grout.
Alternative spreading agents
But there is no need to worry: you do not have to do without a beautiful natural stone terrace, because there are good alternatives to road salt. Instead of freeing your terrace slabs, stairs or paths made of natural stone with structural and environmentally damaging de-icing salt from the risk of slippage, you can safely use other variants of winter litter. With sand from gravel pits and sandy beaches, for example, good results are achieved in terms of slip resistance. Fine sand and fine quartz sand are recommended for travertine. You can also prevent accidents by slipping with grit or grit. These are artificially crushed rocks that have an angular grain shape and are incorporated into ice and snow when subjected to pressure. “In the case of ice and snow, I recommend making granite slabs or quartzite slabs with grit and natural stone slabs with a softer structure, such as travertine and limestone, walkable with fine sand,” confirms natural stone consultant Adalbert Lange. So take care and best place a grit container with sand or grit within reach of your paths, stairs, and terraces, so that you and your natural stone are optimally protected in icy weather!
Additional tip: Already when creating the terrace made of natural stone, pay attention to a gradient of approx. 3%, so that condensation can drain off easily. In this way, possible frost damage to natural stones from freezing water can be prevented in advance and the terrace can be made winter-proof.
Don’t worry about frost resistance!
Good news for all-natural stone fans and builders: With professional installation with sufficient water drainage, i.e. on fine grit with a 3% gradient, travertine slabs can be laid outdoors without hesitation.
Are you unsure which grit to use or do you have any questions about your natural stone floor? We are happy to help!