Hi
Is there a way to cut walls without getting N-gons faces ?
I don’t know what to do, especially when I make a hole on the wall. oh god 
How to avoid getting N-gons or triangle when cut or make a hole on the wall ?
Select the 2 vertices where you want the edge and press “J”.
You can also use the knife tool “K”, but it can get a more complicated.
As show the blue line, using knife, you correct the topology… Sometimes, it is needed to correct the topology manually.
Since you have an answer already, I’m going to ask the sort of question I hate in a Q/A…
Unless your walls are changing shape during an animation, does it matter if they have n-gons?
And I understand if you’re doing this out some (perhaps misplaced) sense of purity because I do it, too. But I also know that attending to details like these if they aren’t necessary can keep a person from finishing a project because s/he gets bogged down in an endless loop of details.
Unless your walls are changing shape during an animation, does it matter if they have n-gons?
I’m not using animation and i don’t know much about it.
This issue come up when i start texturing my models. Some people avoid to do it for me because this issue.
I thought there will be an addOn on blender to solve this problem, but it looks like i have to do it manually.
Thank you guys for all this information.
Yes it does