Flagstone is a common type of flat stone that is generally used for paving slabs, fences, roofs and patios and is available at any home improvement store across the nation. As more and more designers focus on natural appeal for interior and exterior applications, it is only natural that flagstone is becoming one of the most popular types of patio material. Flagstones come in a wide variety of colors dependent upon the organic cementing material that bonded the sediment together over time.
Heaving is a common occurrence around the world and happens when ice forms beneath the surface of the soil during the winter months when the temperatures drop below freezing. Since the ice grows toward the direction of the heat loss--upward--the soil is eventually forced to buckle and bend to make way for the ice, otherwise known as heaving upward. There is unfortunately no way to completely counteract heaving, but there are a few methods that can be used to reduce the chances of heaving disturbing your flagstone patio.
One of the most important aspects of any flagstone patio is drainage because, the less water there is underneath the patio, the less chance there is for heaving to occur during the colder months. As a result, it is paramount to the longevity of a patio for there to be an extremely porous material used for the base so that water will drain as efficiently as possible, thus avoiding any potential damage to the installation.
While stone dust is available to be used as a base for flagstone patios almost as commonly sand, there are issues with stone dust that can cause problems for individuals living in areas where there is an excess of moisture or above average rainfall. Humid regions tend to fare worse with stone dust, because stone dust packs far more compactly than sand, which means water has less of a chance to drain. While a good product for use in arid areas, individuals living in humid states will want to avoid stone dust for their flagstone patio.
Sand is the most common and most effective material used in flagstone patio installations. The best type to use is beach-like sand. The reason sand works so well is because it not only packs good and has plenty of flexibility for shifting but it also has superior draining effectiveness, which reduces the chance for heaving to occur. Sand can be used in both arid and humid climates and is the best choice overall.
In short, where you live has more of an impact on your decision to use stone dust versus sand than personal preference. While both have been proven effective over time, sand is generally considered to be the superior, although neither can guarantee complete protection from Mother Nature.