External window Sill regulations

Quick question to the builders out there. Does a an external window sill need to be wider that the window itself and is there a minimum distance it needs to stick out past the outer edge of the external wall?

Any comments please

Never known a minimum distance, as long the cill past the external wall to allow rainwater to be dripped off the drip bar of the cill away from the wall, too close will get damp wall

Normally the window cill would project beyond the outer face of the wall beneath it to throw the water off. It depends on the detail really, some window cills have cant bricks and these don't project beyond but then the actual cill would project beyond the front of the frames over the top of the cant bricks and is designed to ensure water cannot drain back into the building. As long as the gap is sealed and exposure isn't an issue it should be ok without projecting.

Thanks guys javascript:emoticon('')