they won't let you do inspection pits here, don't want you dying because you left the car running and didn't ventilate :BangHead:. some people have done one after the garage was built. easiest way is get the contractor to pour the slab thin in the area you're planning to dig out.
yes, you need planning approval here in the uk for a pit too. i know guys who do the pit, then lay the slab over it with plywood sheets just an inch or so below the surface covering the pit. easy enough to open it up after inspection then.
there should be a way round the choking yourself risk, like motion sensors in the pit that switch on an extractor fan one end for the whole time you're in there working along with another at the other end feeding fresh air in. shouldn't be hard to build in at the start.
neil.
