Is Sandstone Paving Permeable? Is it porous?

February 21, 2024

Sandstone's porous nature enables it to absorb rainfall, qualifying it as a permeable paving variety. However, sealing procedures applied to most Indian sandstone slabs, in the fabrication process tremendously reduce moisture absorption potential. In addition to its functional advantages, the variety of sandstone paving colours available allows for customisation to suit any design aesthetic, enhancing the visual appeal of outdoor spaces.

What makes sandstone permeable?

Natural tiny pore spaces permeate sandstone's composition of fused mineral grains. Exact permeability levels depend on thickness and stone variety when it is being made. Unsealed 4 cm Indian sandstone slabs may allow 5-15% water infiltration. Sandstone with looser sediments generally exceeds denser stones. Being permeable is just one of the many pros of sandstone paving.

How does sealing affect sandstone permeability?

Most producers seal paving for stain protection and other benefits, but this dramatically lowers natural breathability. Sealing fills microscopic crevices that would otherwise transmit some rainfall. So sealed sandstone paving essentially performs like impervious porcelain. Deliberately unsealed stones retain higher moisture capacity.

Can permeable sandstone withstand winter weather?

Freeze-thaw cycles threaten permeable paving of all types through frost heaving, where ice expansion displaces units. Adequate subsoil drainage underneath prevents water saturation and later migration into crevices during thaws. Timely runoff capture also avoids hydrostatic buildup from trapped moisture. View our content on how to lay paving in winter.

How are porous sandstone pavers installed?

Optimising permeability requires properly integrating the paving sub-base with graded sublayers of drainage stone, geotextile liners, and perforated pipe exits. Sharp aggregation gradients coupled with robust containment edging routes moisture out while resisting erosion. Tight joint spacing deters seed encroachment but still enables some infiltration.

Sealing and grouting the paving after installation allows adjusting permeability - sealed for durability or unsealed for maximum rainfall capture. Responsible sealing techniques and products safeguard health along with the environment.