dave1949
Super Star Member
As the OP, and having done a lot of research before committing to the Superior Walls, I can add what I learned. I too was skeptical about a crushed stone footing. What I learned is that the weight is distributed outward at an approximate 45 degree angle from the direct point load of the wall. This means that a 10" thick wall section will bear on a 18" base for a 4" thick base (4" exterior + 10" wall + 4" interior). An 8" thick crushed stone footing will distribute the weight over 8 + 10 + 8 = 26" wide. Superior provides charts for the thickness of the stone base based on expected loads.
The stone used is 3/8" clean crushed stone and is mechanically compacted (twice in one direction and twice in the opposite direction) to lock in the stone. Adjustments are made to reset the proper elevation after compaction.
The walls are then directly placed on the stone, bolted together, checked for plumb and level, repeat.
One claimed benefit of this process is that there is less hydrostatic pressure against the wall from ground water as the water can naturally flow through the footing and be picked up by your french drain.
The reasons I am using a poured footing instead of the stone (at least for the house itself, the garage will use the stone method) are two-fold: 1) The soil composition and it's load bearing ability, given the higher water table, was unknown during the design phase and the architect was not comfortable with the unknown and the ability of the gravel to NOT sink down further and 2) if there is a failure due to settling of the gravel, then the result can be water infiltration into the house.
One downside of the footing is that I now will have a french drain on the outside, carry the water through the footing to the interior only to pump it outside again.
I'm sure Superior must feel confident about that. I think your arch. made a good choice on your behalf though, given the unknowns about the soil bearing quality. The french drain effectiveness thing is maybe a wash since the drain would, if done correctly, be below the bottom of the wall either way.
It isn't unusual to bring all the water from foundation drains and downspouts into the basement, and then back out when hooking-up to a sewer line, although it doesn't seem logical really.