I'm in the process of building a new house with basement. The deep end and approximately 3/4 around of the basement wall is approximately 8 ft. deep. do I need a French drain this deep basically at the footer. I have waterproofed the block wall with Damtite water proofing. Looking for other suggestions to help prevent problems years later.
So moisture can either come in from below (a rising water table) or come in from surrounding ground water (rain) in the saturated soil.
If it comes up from a rising water table, it will enter the living space from below through cracks between the foundation wall and slab.
If it comes from the surrounding ground water, it COULD enter the living space through the wall, especially if the exterior side of the foundation wall is not sealed properly or through the crack between the foundation wall and slab. Either way the moisture enters the living space, it will need to be collected and disposed.
I think the best way to collect it is on the exterior side of the foundation wall by installing a 6” perf pipe in drainrock and laid 6”-8” BELOW the interior basement slab. (Some use “filter fabric” around the drainrock to keep “fine” soil particles out of the rock and pipe.)
To keep the subsurface water from seeping through the wall, I recommend installing a moisture barrier on the exterior side of the foundation wall and install a 2” thick plastic mesh on the wall to allow water to flow down to the perf pipe. If dirt is allowed to be backfilled against the wall, the dirt could hold the moisture giving it a chance to seep through the wall.
Once collected it needs to be disposed by extending a solid pipe over an embankment or in a collection well and pumped away.