House Foundation Backill

[tmlim]

I'm working on a house with a steel stud embedded in EPS foundation wall. The wall is 8' high. I was told that I need to have washrock to within 12" of the final grade. So it comes out to about 6ft of washrock. Does this makes sense?? I thought washrock was only needed for about 12" above the weeping tile.

 

[oldestguy]

I suggest you search out threads under Soil/ground water under French Drains.

You will find many discussions about drains. You may find that I preach not using gravel, but ASTM C-33 concrete fine aggregate (concrete sand) because the gravel is not a filter.

As to why full height, well some think that if a little is good, more is better, or similar ideas, without merit.

However, if backfill is likely to be saturated, some form of drainage-way down to the drain is good, but not all the backfill.

 

[tmlim]

@oldestguy
Thanks for your input. That was kind of the answer I would expecting.

 

[Mickney]

Run a grain size analysis on the native soil adjacent to the washrock. Using the grain size analysis to spec an appropriate filter fabric to place between the wash rock and native soil.