Flagstone patios are elegant yet they still manage to lend to the area a sense of naturalness not found with brick or cement. They can also be more durable and require little maintenance for their return. Unlike wood patios or decks, there is no need to worry about rot, and unlike cement and brick, they look better weathered and stained.
When building a flagstone patio there are a few things to keep in mind. The best, longest-lasting patios are usually laid with sand and/or gravel. Some people may elect to use a cement foundation or mortar.
While beautiful for the first year, heaving still takes place and the cement and mortar will still crumble and break away faster than gravel and sand foundations. Then when it comes time to repair the cement or mortared foundations, the whole patio will have to come up and new flagstones will need to be purchased.
The best materials for the job are coarse sand and decomposed crushed granite. Although, any crushed stone such as crushed flagstone, crushed cement, or crushed limestone will work well too. However, make sure you do use coarse sand instead of round sand or beach sand since the rounder the sand grains are, the less likely they will hold together.
Optimally, ground granite works best. It acts much like cement in that it won’t track into the house and won’t come out of the cracks. As an added bonus, it provides excellent weed protection. Ground granite also resists heaving and shifting better than any other material. Crushed granite is usually cheaper than pea gravel or other gravels. Crushed granite might even be found for free from local quarries, granite processing plants, or local compost yards. It does pay to shop around.