see where I circled the area where the textures distort?

your blocks are too thin and they overlap. this will cause build problems such as removing surfaces. the texture distortions is caused by 2 visible surfaces that are at the same location and face the same direction.

fix this by adjusting your ceiling block. don't overlap blocks, make the 'flush' with eachother.

best is lay the blocks down, floor, walls on top of the floro surface, then ceilign capping teh walls. cuts out rendering problems with gaps between blocks