On 25 Nov 2005 02:29:04 -0800, a particular chimpanzee named
randomly hit the keyboard and produced:

I think the pipe will be over 1 metre down.
That would be a lot of brickwork over the top. Wouldn't you have the
foundations up either side of the pipe and a lintel across concrete the
concrete "walls" either side ?
Otherwise, the lintel would be supported on the underground blockwork,
which would be hard to construct one metre down. Also, what is a
"rocker section" ?

Right. If you're trench filling your foundations, the drain is a
100mm diameter one passing at right angles through the footing and the
thickness of concrete over is substantial enough, you can probably do
away with the lintels. Roughly speaking, if you can take 45° lines
from the edges of the 'hole' for the drain and they intersect below
the upper surface, the loads should be adequately distributed to
prevent the foundation cracking.

Otherwise, shutter the drain with some compressible material (mineral
wool batts) and cast some reinforcement bars into the concrete above
the drain (two or three 8mm dia bars about 1m long) with 50mm cover
under.

A rocker section:
http://www.odpm.gov.uk/embedded_object.asp?id=1132107
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Hugo Nebula
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