Building extension over drainage pipes sloping at an angle
Anonymous user 09/03/2024 - 3.33 PM
Hello All,
I am currently having a single storey kitchen extension built for 3 bedroom semi detached property (full wrap around).
During the ground excavations, the contractor discovered a rainwater drainage pipe. It is running from left to right of the garden, and will fall inline underneath the extension end wall. In normal circumstances a bridge over design with steel beams would suffice, but given the property is located on a hill, the drainage pipe is actually sloping at an angle upwards from left to right. We have notified this to our architect / structural engineer and are currently awaiting a couse of action.
Just wondering if anyone has encountered this issue, and what solution they adopted?
Are you a tradesperson and able to answer this question?
This is probably an old rainwater pipe from the gutters at the back of the house. You will need to take this out and move it outside the new extension approximately 6 m away into a new soak away.
Answered4 April 2023
0
Anonymous user
The best thing to do is check the pipe if the pipe is in use first if its obsolete get rid of it if it's still in use and in the way redirect the pipe to outside of your footings.đ
get photos of area you are having the works carried out,
drawings you have from the architect and structural drawings,
when was the house built? Ses pit and septic tanks over fill tank
what are the surrounds have you got surrounding properties?
My advice and this needs to be done before your pouring the footing
If itâs something you donât want to disturb then cut 2 boards to the width and depth of footing out of ply boarding, this also needs to be braced together top and bottom with 4x2 and 80mm screws this will shut both sides of the pipe and keeping concrete away⊠for movement purpose drill some 10 12mm holes and thread through some reinforcing bars long enough to sit into the concrete both sides of shuttering this will help with bridging over of pipes when masonry is being done and also movement and shrinkage.. and donât forget you will also need to back fill in between the shuttering on top of pipe with pea shingle upto same level of concrete.
All drains need to slope downwards !
You dont use steel beams underground they will rust away. Bridging should be done using prestressed concrete lintels.
There is a possibility the drain is disused..but full investigations need doing to verify this before removing any pipe. Sometimes the pipe can be diverted to avoid a foundation or at least square it to the building line so the bridging is minimised. The building inspector should be consulted before altering any drain, and a plan agreed. Drains have to be assessed on site so i can only give general advice.
Its also good practise to replace any drain under a building for new plastic. There are excellent adaptors for fitting plastic to old clay.
