I hired a friend to install natural irregular shaped flagstone and 1/4 of the way through the process I noticed that the floor wasn't level in its thickness from stone to stone. He said that's the way it's supposed to be. Another friend told me that it has to be level, otherwise the kids will stub their toes when walking. What's the deal? I told him to stop temporarily. Any help?

Is this interior?

I would think that you would like it to be even, or at least close to even as possible regardless.

A thick enough base( equivalent of thin set for inside work) and some chipping/shaping of the new stones should make for an acceptable surface.

Chip out the new stones that are too high, or try to surface them first, a good cold chisel and some gloves... :)

If they break wrong, removal and replacement are not out of line.

"Friends" are not always as diligent as a professional, remember, you always get what you pay for.

Hope this helps some,

Ken

It's exterior. This was a tough lesson, this ended up costing a LOT of money. Thanks for the input.