Installing 1"x4" trim around exterior windows

Getting ready to trim my exterior windows with Miratec 1"x4" boards. Question. I was going to use 2 equal pieces on each side and 2 equal pieces on the top and bottom. A friend mentioned that I should use a longer piece on the top and a shorter piece (in between the two side pieces) in case water ever got behind the trim and this way it will divert out better. I don't think it will look as good this way. Any thoughts. Thanks

 

Do you have an external sill? You should have the top rail cover the total width including the side stiles, and the stiles should sit on top of your tapered sill. Now, if you have no sill, then the longer top, sides all the way down, and a shorter one between the two side stiles is in order. This is not only for the effect of water drainage, but it looks more aesthetically pleasing.

 

I have a combination of new construction and older windows that I just replace with vinyl replacement with wrapped aluminum. The new construction is a nailing flange to the OSB. They are Anderson Casement and picture windows. Window frame is the same all the way around. The older window we just replace we removed the old brick mold and furred out the area so the aluminum trim could attach to a level surface. We are putting trim up and then running new Hardi siding to it. Therefore, I guess in my application you are saying to go with a longer top piece, equal side pieces and a shorter bottom piece. Correct? Thanks

 

Roger that, since all is flat. Make sure all the windows have sealing tape applied all the way around and are flashed properly, and you should have no problem.