Foul water drain through footings

[ashk57]

Hi, new to the site and requiring some help with an extension I'm building.

I have dug out for trench footings and have a clay foul water pipe running through the corner of my footings And separates the front and side trenches, the building inspector would like me to lintel over it but the height of it is in the middle of my footings and Im just at a loss how to do this.

can I construct a 18mm ply wood box filled with pea shingle and then pour my footings or should I shutter either side of the pipe bed some lintels allow them to set and then finish the pour?

Any help on the matter would be greatly appreciated, Ash

 

[Jackrae]

Your inspector is asking for a "bridge" so that no shear force is placed onto the drain once the wall is built. Therefore you need to deepen the footings either side of the drain and build short pillars onto which you place the bridging lintel. Then, box in the drain to ensure that the main footing pour does run and encase the drain, otherwise it will place shear force onto the drain.

Alternatively you might want to consider replacing the clay drain with plastic for the full length under your extension. Then haunch the whole length in concrete

 

[ashk57]

Thanks Jackrae, that has helped me a lot

I have been thinking about replacing the section with plastic, when you say haunch am I correct in thinking that once replaced I would cast it in concrete allow to set then pour my footings?

 

[Jackrae]

Yep, that's what my building inspector required. Dig trench for new pipe and ensure that pipe is fully encased in concrete. In effect you end up with a plastic lined concrete pipe. Seems a bit of overkill but it was either that or they didn't pass the inspection.

 

[ashk57]

cheers Jackrae, Thats what im going to do, can I just ask did you wrap the plastic pipe in anything and how much room did you allow around the pipe?

Cheers, Ash

 

[Jackrae]

no wrapping used. If memory serves me right there was no stipulation about sides or under pipe but he wanted 6" (150mm) minimum covering over the pipe.

 

[ashk57]

Thank you very much Jackrae

 

[noseall]

I think you two have got your wires crossed or that Ash misunderstands.

If a drainage pipe passes through foundation concrete, it must be constructed in such a way that if the concrete settles, it does not have any effect upon the pipe.

There are several ways of doing this either by shuttering, sleeving, wrapping in compressible material etc. Just renewing in plastic is not acceptable.

 

[Jackrae]

No one has suggested that. The requirement for a lintel to remove wall load from the pipe still stands. I believe we had digressed onto talking about replacing any pipework that was running under the extension floor. If the floor is solid then the line requires concrete haunching (increased depth of concrete) before the floor is laid. This ensures there will be no future problems with cracked clay pipes