DIY Doctor UK DIY Forums

Over 10 years ago the previous owners of our 120 year old Victorian London house were very close to getting a basement conversion. They had 4 or 5 test pits dug, got the quote, plans, planning application etc and then I guess decided they couldn't afford it.

The cellar is about 4.5m by 6 m with about 1.75m headroom, slab floor laid probably 30+ years ago. The soil is london clay.

Fast forward 10+ years, I am properly filling in those trial pits (they were filled with tiles!) when I notice that on one of the pits they have gone right down to the bottom of the footings and appear to have actually cut off the brick footings back flush to the wall!

The whole area affected is just under a meter of a 4.5 meter wall (photos show it better).

What is the most sensible way of making good this mess? I don't want to just fill the hole with clay because as you can see, the void extends under where the footings were for this part of the wall.

I was thinking of just filling up to the bottom row of bricks with concrete (possibly at a 45 degree angle from the brick to form a bigger base) and then to use mortar (lime mortar I guess) to fill in the gaps in the wall where they have removed bricks?

Does that sound sensible or is there something better I can do?

I can't believe they left it like this for so long but now I've seen it, I want to sort it out asap.

Here is a closer view of the pit - the water usually appears after prolonged rain and drains away after a couple of days