Mesh Cut Problem

[Anonymous]

Hello everyone!
I have this mesh that is one piece and i need to cut it into 2 pieces where the brown wall is. how can i do this without damaging the heights of the source mesh?

[Anonymous]

i cannot attach the image i dont understand why
but the point is i need to cut a mesh into 2 pieces

[Anonymous]

Split option, I tried to use it but it's not as simple as in AutoCad

[Anonymous]

Split option should work (if its a straight line) and heights along the split should be calculated accordingly.