Basically, I'm trying to model an house to use later in Unreal Engine 4. I've set the scale to the one reccomended for UE4 already.
So, let's say I want one of the walls to be 3mx3mx20cm. This is easy. Add a cube, change the size in the transform menu.
Now I want a window that's 1mx1mx20 in size. But how do I make a precise opening the my wall? What I've been trying is to add a cube, make it 1mx1m, and then use it as a guide to place four edge loops. The problem is that this is not exactly accurate, so I usualy end up with openings that are like 99cmx98cm, or 99cmx101cm. So when I model my 1x1 window, it won't fit exactly, leaving seams.
Is there a better and more precise way?