Precise openings (windows, doors )in meshes 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?
You can use snapping limiting transforms on an axis.

Basic house with a separate window object :


Select your house, enter in edit mode (tab)
Activate snapping, open the menu and choose Vertex :


Add your edge loop (Ctrl+R) place it anywhere. Move your newly created edge loop with g, lock your movement on X axis (X) and move your mouse close to a corner of your window. You'll see a circle appear where the movement can be snapped (window corner vertex). Click LMB


Repeat this actions on the 3 other loops with the 3 other corners (X and Z axis)


You can move along all axis, 1 axis (with X, Y or Z) or 2 axis (with Shift+X all but X, Shift+Y all but Y, Shift+Z all but Z).