New water feed and foundations

[trevorbayliss]

I am doing an extension on the house. The back right hand corner is going to have the wall extended by 5m's. At the point where the old and new walls will meet i am intending on bringing a new plastic water feed up the drive and sitting just inside this rear right hand corner.

So the pipe will turn and head under the proposed concrete foundation area. I have to lay the water feed at 750mm depth and my foundations will be going down to this depth or a little deeper and then come up 250mm in concrete. I will then use foundation blocks to get to ground level.

I am thinking i need to do the foundation first, but i am not sure what the finished height will be at and the water feed must be at 750mm deep all the time. So if my foundations go ok and i need to excavate to the proposed 800mm, i will then come up 250mm in concrete and so the new water feed at this point will be 550mm deep.

Any ideas on what to do here ?

 

[Newboy]

Install a duct to allow for the new service to be pulled through

 

[trevorbayliss]

Ok, so is this just a length of 4" soil pipe then ?

Do i set this duct fully under the foundation strip ? So if the bottom of the foundation is 800mm deep, the duct fits under this depth, so goes to 900mm deep. This means digging a little deeper as the pipe nears duct entrance. This seems pretty straight forward.