I've written about the proper way (or least the way it is done here in the South) of cutting wooden baluster bottoms for outside balusters. These two images were taken from a home in Natchez, Mississippi. Natchez is the home for many beautiful Antebellum (before Civil War) homes.

The bottom rail, as you can see, has an upside down "V" cut into it. The bottom of the balusters are cut to fit the upside down "V". Why is this so you might ask. This is simply done to shed water and reduce the opportunity for rot to develop in the baluster bottoms. Water tends to percolate upward on the bottom of the baluster and create the condition for rotting. So have your carpenters do it this way and have your painters primed the bottom of the balusters before they are installed.  That's an order!!