[ul]
[li]Pile type (difficult to omit the cap with driven piles);[/li]
[li]Relative dimensions between the pile and the column;[/li]
[li]Differing concrete grades between the pile and the column;[/li]
[li]Allowance for tolerances (usually piles have a much larger positional tolerance than columns);[/li]
[li]Contractor preference (it can be difficult to accurately place columns starters in piles).[/li]
[/ul]
