Building Undergound

[Cashboy]

My start on this subject is:

Does one need planning permission to build below the surface (under ground).
I am under the impression that you can build an underground room in your garden without planning permission.

Is that true?

If so can somebody guide me to the government regulations regarding this.

 

[^woody^]

If its not directly under the existing house, you need planning permission. TCPA 1990 and GPDO 2008