Banty wrote:

-snip-
What exactly do you mean by 'rotting' the concrete block?


Constantly wet blocks degrade.

Interior french drain systems usually include a way to drain the bottom blocks
of water, if any, to redirect along with water in the trench.

Usually is a mighty big word. And even if they are installed, a small
weep hole is more likely to clog than a 4" perf-pipe.

Another advantage [in northern climates] of keeping that groundwater
outside of your house is heat loss. The best insulation is on the
outside of your block under a waterproof membrane. Then the slab and
walls become part of your heat sink. Water running through is a
constant source of 50degree or less coolant.

Jim