Hi Adam,
I'm not sure if this is specified in IPC specs, but, all companies
I have worked with have all specified 0.060"(1.5mm) clearance from
any metal work and min 0.050"(1.25) from edge of the board to track.
Hope this helps.
David Hill
Mullard Space Science Laboratory
University College London
Holmbury St Mary
Dorking
RH5 6NT