Building A Base

[FallenApex]

I wanna build a full Cinder Block base, but the only thing stopping me is the Metal Floors. They're kinda expensive to make/buy. I was thinking that I can build the whole first floor with Metal Floors, and then all the floors above with Wood Floors and still use Cinder Block Walls. Would there be a problem? Can someone get into my base?

 

Example:

Bottom Floor: Metal Floors + Cinder Walls

Second Floor: Wood Floors + Cinder Walls

Third And Last Floor: Metal Floors + Cinder Walls