Existing drainage through concrete footing

[structural2000]

I am doing some alterations which involve casting existing drainage into a new foundation. The existing drain runs perpendicular to the strip footing, which has been designed by a structural engineer (me).

My question is how do you go about actually sleeving the pipe through the footing, especially considering that it’s existing? The pipe needs a minimum 25mm void filled with compressible material (potentially Rockwool) surrounding it to avoid any issues when the footing settles.

Anyone know any products you would use for something like this, and how to go about sleeving an existing pipe?

 

[stevie888]

Is yours or public? If the latter you generally stop 150 clear either side woth your concrete and use a couple of PSC lintels over but to Water Co's requirements. If it's yours then just BC to satisfy so wrapping may be ok, but personally the reduction in volume of dig, muck away and concrete vs a couple of lintels is a pwerful argument for doing it that way,

 

[structural2000]

I forgot to mention that the footing is effectively a ground beam and has reinforcement running through it, so it needs to be continuous with the pipe cast in. The drain is a private utility.

 

[stevie888]

That's an important detail to omit!!

What does effectively mean though?

So best options: lift the beam so pipe goes under with say 50 clear or.. drop the beam so the pipe goes over again 50 clear. If neither is possible deepen the beam so your main steel has continuity and cover and maintains 50 clear to the pipe. You may need to add a couple of trimming bars

Casting the pipe in would be an option but you would need to provide a rocker pipe either side (300 long flex joint at each end).

For the last 2 options you would need to clear with BC ahead of time.

Further thought: if it's a piled foundation then tweaking the pile locations if necessary and adopting a cantilever section could work.