Either pile foundations or shallow footings may be appropriate depending on soil conditions and location. The first thing to do is obtain a soil report. This will provide soil logs and recommendations for allowable friction or bearing values to be used for piles and shallow footings at various depths.

The choice is usually made on the basis of economics. If the site will be subject to freezing, shallow footings must be placed below the depth of frost penetration. If the soil near the surface has low bearing capacity, you might be tempted to use driven steel, timber or precast concrete piles, cast-in-place friction piles, belled piles or compacted piles. But there is no guarantee that soil at greater depth will be satisfactory for any of these piles, so a soil report is mandatory.

Often there is a tendency to favor one type of foundation in a particular location. In some areas, cast-in-place friction piles are favored for light loads. Belled piles tend to be favored for heavy loads. In other areas, driven precast concrete piles seem to be the norm.

You can specify alternative pile schedules on your foundation plan based on the soil report and let the contractor select the most cost effective type. Similarly, you can specify an alternative design using footings.

The use of screw pilings can be a less expensive method of supporting constructed loads than driven pilings. It all depends upon just how deep one must go to reach soils suitable for carrying the load to be placed on it. These types of pilings are placed using a hydraulic power head that screws the piling into the soil. Little or no digging is required. Additional sections can be added as is needed as and necessary to achieve the load bearing capacity required. However soil borings and an assessment of the specific location of each anticipated screw pile is advised to reduce the cost of possibly driving piles to a greater depth than is necessary for each individual location