Is the paver base material set directly on the subgrade?
No. A separation fabric or “geotextile” is used under all paver and garden/retaining wall installations. The fabric is laid on top of the compacted soil in the excavated area and along the sides of excavated areas. It is made of plastic threads that allow water to pass around them, but not very small particles of soil beneath them. Geotextile separates and contains the base from the underlying soil subgrade. It allows the base to shed water, and prevents the soil around it from working its way into the base. Without geotextile, the soil will work its way into the base and weaken it. This is a slow process that happens when the soil is saturated with water or during periods of thawing. Geotextile stops this process and extends the life of the base by many years. This is especially important where the soil contains a lot of clay. Geotextile provides an insurance policy against base failure.
