[Cob] Gravel Bags / More Foundation Thoughts

[America Leavenworth]

*Michael wrote:  **....The implication being that soil-cement bags DO wick
water through capillary action? Thoughts/experiences from anyone?*



Well in 'formed/poured' cement or in sequential pads without sealant of air
breaks between layers - water can wick, through said capillary action, to at
least 70 vertical feet (personal experience) up through concrete and is said
to go higher (construction reference materials).



*Shody wrote: ...I think the drain pipe should be in gravel and the gravel
should be in filter cloth to keep soil out of the gravel. As I understand
it, even the filter cloth has an expected life, after which the system is
less effective, but the expected life is better than not using it.*



Working with stormwater drainage and bioretention areas - all the
underground drain piping I design no longer uses filter cloth of any kind.
I've seen quite a few clogged filter socks causing an entire drainage system
to fail.  A 'pea gravel diaphragm' is preferred.  Essentially you create
a gradient of substrate layers to the soil surface to allow particulates to
be filtered by voids in the grain size.  Large gravel in the trench where
you are piping is surrounded by smaller gravel which is surrounded by coarse
sand, which is surrounded by fine sand etc.



$.02,

America