BigWallop wrote in message
. uk...
"Tony Strong" wrote in message
...
I need to cast a foundation for a wall, and for the surface levels to
be
reasonably accurately.
It will be 300mm deep and 600mm wide, with a 68mm step in the top edge
so
that the rear shuttering only needs to be 232mm tall. The whole
foundation
will be below ground when completed, so we were looking to back-fill the
outsides of the formwork prior to pouring the concrete to help prevent
the
formwork distorting.
(bad ASCII artwork of design)
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||v^v^v^v^v^v^v^v^v^||
base cast onto excavated surface
Using 18mm OSB as the side shuttering/formwork and 50x50x600mm timber
pegs
to locate and hold it down, what spacings would you recommend for the
bracings? These shutters are a one-off and will be 22m long, so I do
not
want to make them over strong and waste monies that could be spent
elsewhere.
thanks
Tony Strong
Why not use the soil itself as your shuttering? Why go to all the expense
of building a whole timber box, when you can line and backfill to the
sizes
you need. Brace out the internal sizes, backfill and compress the soil to
hold it all. As you reach the internal bracings, remove them as you go
along.
Thanks for the advice, I've uploaded a couple of diagrams,
hopefully showing the plan more clearly than I can explain:
http://www.hebdenhey.org.uk/shutter1.gif - an isometric view of two of the
sections of shuttering
http://www.hebdenhey.org.uk/shutter2.gif - a more detailed view showing the
downstand shutter
"suspended" between the front & back faces.
The 2"x2" stakes will extend further out of the ground if required,
as it is very stony and they will not be likely to be driven fully home.
finally, a section of the proposed wall is:
http://www.hebdenhey.org.uk/wallsection.gif -
this shows the foundation and the interlocking blocks to be dry-stacked,
the wall will be back-filled with clean 20mm gravel
The reason we need the heights of the step is to ensure
the wall slopes back at a slope of 20 degrees.