On Apr 3, 7:01�am, Jim Elbrecht wrote:
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

if your building a brand new homew install BOTH, the trouble is most
of us own existing homes, and beyond the obvious downspot clogged a
interior french drain is the MOST effective.....

been there done all this.....