-
There's planning in for someone on our road to do this. Big long underground extension for gym/cinema room etc.
Great for causing flooding problems for neighbours.
New tanked basement goes in, messes with previously happy underground water flow. Water flow changes and affects some random house nearby.
Quite often someone getting a basement done causes problems for houses two or three doors away. And there's often fuck all that someone affected by this can do about it other than £££ to get it fixed themselves, which then affects some other random person nearby, etc.
It's <2k sqft so you'd have to be assuming major footprint expansion or serious structural issues to get to that level, right?
There's already a basement and loft and a quick look on the satellite imagery suggests there is no precedent for a long rear extension. What's left - burrowing under the garden?