[Strawbale] Saskatchewan foundation

Michael lough michaelklough at sympatico...
Wed Feb 15 17:40:02 CET 2006

just a few thoughts Mark…

Not sure if you need a permit for this job or not but if you do you
might have to do what is required for the Sask. climate which does
in fact have a frost line of around 5 feet deep? This is possibly
even lower in some exposed locations. It gets quite cold there for
quite some time?

You say there is no rubble locally so a rubble trench is out of the
question? As far as I know actual "rubble" is not often used, 3/4"
gravel being more often used as "rubble". It is hard to believe that
this is not available (or at least something else that would allow
drainage). But perhaps the building site does not have a slope to
drain water to daylight anyway?

The bottom of a RTF  would have to have drainage to preclude any
freezing of water collected there and consequent "heaving" But if
you cant do this… You cant do this…

If you allow that one way or another you have to connect to the
frost free zone  (say 6 feet down) then what are the choices if you
dont want to go the distance and excavate for a RTF or a brick or
block foundation wall? Not many other than suspending the building
on something that will reach down to  6 foot below grade? One way or
another you have to excavate to a certain extent to below that frost

Well this is my best shot. IF you do have a sloped site and the
distance from the top of the trench to daylight drain opening six or
so feet below  is not too far away requiring much labour then why
not use a rock (boulder) filled trench and cap it with a grade beam
concrete pour on top of the compacted rocks? This would give you the
flat form for bales etc on top? The underside of the pour could use
a cloth type restraining material which could be tucked in beteen
the rock tops to stop the concrete (stiff mix) from dropping down
inbetween the rocks and be pinned to the inside of the wooden forms with 2x1
strapping. Use some rebar in this beam.  No slope? Do the same thing
but use a "French" drain to a pit with a solar powered sump pump if
a "mains" connection is not possible. If you use a pump then you
possibly need not go down 6 feet if you used XPS say 2 feet down
horizontally and one foot up from the bottom of the trench thats an
insulated 3 feet deep trench with nothing to freeze in the bottom.
Might work?

If this is a non residential project not requiring a permit then it
is possible you dont have a soil profile for the site? This could
tell you if there is sufficient drainage on the site to not worry
about a flash flood that will instantly freeze and heave your
building? Maybe the rain justs heads straight down without stopping

best Michael

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