I am almost finished my bath renovation. The shower door folks are coming to measure tomorrow. Subway tile in my 3x5 shower goes all the way to the celling (8'4") I am wondering how much space to leave on the top, so that it doesn't get so steamy and peel paint etc? 6 " , 12" or none at all. I have an exhaust fan. Any other musts? Someone told me about some sealing to ask for which makes the shower doors easier to clean...