supporting edges and smoothing
 

Hi
Basic question about something I need to improve upon. It seems that properly supporting edges to hold shape when smoothed is simple because I dont see alot about it. And i'm using maya 2014.
In making a square window in a wall I have tried deleting the window face leaving a hole and extruding inward leaving an indentation in the wall. Both cases upon smoothing the window distorts into a roundish shape. Have tried adding supporting edges and bevelling the edges but it still looks bad. The only way i've found it to work decently ends up with edges running all thru the model on each side of each edge of the window.

So basically if you're making a building or a wall and want an inset window what do you do so it keeps that nice shape when smoothed? Thanks again for any advice
Scott