International building code provides some requirements about dimensions of deep foundation. The requirements are classifies as precast and cast-in-situ or grouted-in-situ deep foundation.
Precast deep foundations
Minimum dimension in lateral direction of precast concrete element of deep foundation should be 203 mm (8 inch). Square element should have chamfered corner.
Cast-in-situ or grout-in-situ deep foundation
Dimension requirements of cast-in-situ and grouted-in-situ deep foundation are classified based on cased and uncased deep foundation.
Cased deep foundation
Nominal diameter of foundation elements of cast-in-situ deep foundation having permanent casing should be equal or more than 203 mm(8 inch).
Uncased deep foundation
Cast-in-situ foundation elements not having permanent casing should have diameter at least 305 mm (12 inch). The length of elements should be limited to 30 times average diameter.
The element of deep foundation should be designed and supervised during installation by registered engineer having professional knowledge in geotechnical engineering and especially on deep foundations.
The foundation engineer should provide a report about design stating that foundation elements have installed complying approved construction documents.
The outside diameter of micropile should not exceed 305 mm (12 inch). Minimum diameter is as discussed above.