Types of Bluestone Patios
A question that often comes up when discussing bluestone patios are the different varieties of bluestone pavers. To the untrained eye they may all look the same, but, there are actually a number of differences that effect the cost, appearance, and installation methods.
Natural Cleft Bluestone:
Natural cleft bluestone describes bluestone that has been split into layers during the quarrying process. Bluestone is a sedimentary stone, meaning that is comes from sediment that has been fused together over time from the enormous weight and pressure from above. Natural cleft bluestone is formed closer to the surface of the earth than other bluestone. Without as much pressure on the stone, lines of de-lamination or horizontal cracks form which make it easy to split into layers. These layers are then cut into rectangles to make the bluestone pavers you see today.
As it is naturally split, the bluestone pavers have some irregularities. The surface of the stone will have more bumps and texture, and each stone will have somewhat varyied thickness. Natural cleft bluestone also tends to have a range of colors from blue, gray, purple, and rusty orange.
Although the quarrying process takes less machining and makes natural cleft bluestone less expensive than other bluestone, the varied thickness and irregular surface makes it more labor intensive to install.
Thermal bluestone is formed deeper within in the earth. With more weight and pressure above, the stone is solid and must be broken off in chunks and then saw cut into layers. The saw cut leaves a very smooth, unnatural surface which then must be re-textured. This is the ‘thermaling’ process which gives its name. The stone is wet down and then heated with a super hot flame until the surface flakes off, exposing the natural roughness of the stone.
Thermal bluestone is more expensive to produce, but, the stone is almost perfectly uniform in thickness. This makes the installation and leveling process less labor intensive.
Thermal bluestone then comes in three different color varieties, full color, regular, and true blue.
Full Color Thermal Bluestone:
Full color thermal bluestone is less common and slightly less available. It is thermal cut stone but still has a ranger of blues, grays, and purples. The colors will not be as pronounced as Natural Cleft Bluestone, but more so than other thermal bluestones.
Regular Thermal Bluestone:
Regular Thermal Bluestone is most common. It will come in a mild range of blues and grays.
“True Blue” Thermal Bluestone
“True Blue” Bluestone has been hand picked and sorted so that all of the stones are identical in color.
Irregular bluestone, also called “stand-up bluestone” or “flagstone” is naturally cleft bluestone that has not been cut into rectangles. Irregular bluestone is sold by the ton instead of by the square foot and is generally cheaper in cost, but, much more labor intensive to install.
Irregular bluestones will vary greatly in shape, size, and thickness. Depending on the desired look, they need to be cut and shaped to fit together, and leveled one by one.