"What that brainless f**k-wit"...do you want to carry on this conversation somewhere else, you deranged degenerate? You're obviously not a full shilling...I think you're in need of a lobotomy
"doesn't realise is that you can actually put insulation on the INSIDE doh"
Actually, you can, in the form of loft insulation, draft-poof windows and doors, insulated plaster-board, insulating plaster and thermal/insulated wallpaper.
If you read my post, I was having a dig at Aron Squirrely and agreeing that you CAN put insulation on the inside, thus giving his luddite jibe a smack in the gob. Your reaction was rather funny though.
That's really the critical point. If the driveway was plenty wide enough losing 4" wouldn't be a problem (to me) but you do get tight driveways where 4" can make a difference. To answer the OPs question, the boundary line would be the wall - not the foundation. This is the standard legal presumption where there is no contrary evidence and in all modern conveyances the foundation and eaves projection is granted as an easement over the adjoining land.