[C4D] Cutting Objects / Creating tiles

Hi there..

I´ve a small problem with C4D.
I created a square room. Each side has a size of 15m.
Now i want to cut them into 9 tiles, each with a size of 5x5m.

Now i delete 7 of those model tiles, so only 1 straight and 1 edge are left.

What i want now:

if i put 3 straight walls in a row, they need to fit each other without mesh holes. same if i combine 2 straights and an edge or 2 edges..etc

Simply said - i want to create room tiles.

Problem: each try, the walls have different vertex positions on their edges.. so they don´t fit to each other ._.

Question: is there an easy way to manage the Tile Creation in C4D?