When treating the soil underneath a slab, which drilling method is NOT commonly used?

The method not commonly used when treating the soil underneath a slab is diagonal drilling. In pest control, especially when dealing with treatments like termites or other subterranean pests, the techniques typically employed focus on maximizing access to the soil directly beneath the structure without unnecessary complications.

Vertical drilling is widely utilized as it allows direct access down into the soil from above the slab, making it straightforward for applying pesticides effectively into the targeted areas. Horizontal drilling can also be useful, particularly in scenarios where access is limited, and there is a need to reach areas under the slab without disturbing the surface too much. Subsurface drilling is another method that is employed primarily to inject treatments into the soil underneath a structure at various depths directly.

Diagonal drilling, on the other hand, does not provide any particular advantage in scenarios where the goal is to treat the soil beneath a slab. Its angled approach can complicate the process without offering significant benefits for pest control treatment. Therefore, it is not typically a method used in this context.