Basement bathtub install

I'm helping with a basement finish and had the following question. Why does the overflow pipe from the tub go straight into the p-trap instead of the tub drain? Reason I ask, is we have rough-in problem with the location of the branch waste line which would go away if we went directly to the p-trap from the drain with a tee to the overflow. Any thoughts would be appreciated.

There are two methods of installing a tub drain: a direct drain and an indirect drain method; the indirect drain is the most common method. The direct drain is the method you are hoping to use and it will work fine.

drain

1. The conventional connection gives a degree of latitude in the location of the "P" trap.
2. To go directly to the drain requires a different style of drain fitting, called a "toe outlet waste", and it has to be EXACTLY in the correct position when the tub is installed.
3. You cannot use a conventional overflow set up with a tee after the drain and then an elbow up to the overflow. At least not if you EVER intend to be able to snake it when the drain plugs.