Leaking cellar/extension

[NanaHawk]

Hello all,
I was hoping to pick the brains of the experts here with a problem I need to solve.

A few years ago I had an extension built professionally and, in order to bridge over some water pipes, it was designed with a reinforced concrete base that rides over the pipes as it sits on foundations leading out from the house (is it called flying?). Now I am getting water seep in at the base of the wall into the cellar space beneath the new kitchen. On Saturday I found a centimetre of water across most of the cellar and I swept it through to dry it all out (including throwing out some material that had become sodden and mildew). It was all dry but then quickly soaked again with the rain on Sunday morning. It was so quick that this is a major problem.

I have now found that my neighbour has built their ground level up against my extension wall by about two feet which is a major cause of my leak but I am also wondering why there is a dpc layer between the first course of brick and the concrete base - is this normal?

I need to convince my neighbour to remove their encroachment but do I also need to get the dpc removed?

If anyone can provide some words of wisdom it would be much appreciated.

Many thanks

 

[ree]

Why not post pics of:
- the exterior of the extension esp. the "encroachment" elevation?
- the cellar where you suspect water of entering?
- the DPC and the brick course and concrete base detail?
- the interior of the kitchen esp the sink and appliances wall?

I'm assuming a house with a cellar at the rear (below the rear elevation).
An extn was built against that rear elev. wall?
Your kitchen is in the extn?
The extn has a solid floor?

Where does the pipework run under the extn?
Where is the nearest manhole?