There are three basic shape categories that flagstones can be classified into: Irregular, Semi-Irregular and Square Cut.

There are two standard installation methods, one is called “wet construction” and the other is “dry construction”:

Wet Construction
The basic process for this type of construction is 4” gravel base, a 4” reinforced concrete slab and then the flagstone is set into a 1” grout setting bed.

Pros – More permanent construction and less maintenance
Cons – More costly, best installed by a professional

Dry Construction
The basic process for this type of construction is 4” compacted base of quarry process and then the flagstone is set into a 1” bed of concrete sand. Stone dust, sand or gravel is used between the stones for the joints. There are several variations of the dry laid method and it is best to have a contractor decide which method is the best for the specific jobsite conditions. An edging of some type should be used to help minimize the stones from shifting.

Pros – More cost effective can usually be installed by the average person.
Cons – Joint requires maintenance, shifting of stones can occur.