I have to cap some drainage in concrete due to it being fairly
shallow. The PVC drainage involves an inspection chamber and some
length of the outlet pipes, up to a height above the outlet pipes. I
was just going to surround the whole thing with concrete, making a
solid block, making if pretty much indestructible and immune to any
possible future leaks in the joints (they test OK now and there is no
undue stress on them !).
I had a look in part H, and there is this thing about using
compressible board at all the joints to provide movement joints. Well
I can see some advantages with this, but a lot more problems, since it
is creating a weak point where if you did get a leak one day, you
would be powerless to fix it. And it would be hard to ensure there was
no linkage between the sections as you poured the concrete anyway. And
also, what compressible board would you use here ?
In practice does anyone do this, rather than just embedding the whole
lot in a solid block of concrete ?
I must admit I forget to ask the BCO about this when he came round to
give me advice recently. But he did say that a band seal connection I
had made was OK for the regs, but could drop when bedded, and I
suggested surrounding it with concrete and he said that was a good
idea to stabilize it, and he said nothing about requiring movement
Yep. Regs say on exit from the concrete, use a rocker joint to protect
against this problem (which I would do ).
The part that would need capping is the depth to be within the
compressed MOT layer. (screed 75mm, concrete 125mm, celotex 75mm, sand
25mm, MOT 125mm). By the way, it's this depth so a required internal
inspection chamber is within 600mm of the finished floor so I can use
a mini access chamber. One method is to pour the slab over the drains
so they effectively hang from the slab, which is a rather horrid
method since you can't check anything until it is too late !
Also, since the drainage has been layed before the MOT compaction, the
options are limited.
No, the BCO looked at the band seal, said can't fault you on the regs,
and suggested replacing it with a PVC connection. Thing is, the band
seal is providing a slight change in angle (within regs). I could have
used a variable angle connector, but now the two ends are fixed, I
need a slip junction. So a band seal is OK, but BCO said it may drop
when bedding. I said it could be encased in concrete to make it rigid
and he said, yeah that would do it !
All of this regs / BCO stuff is so much fun !
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