Hello All, Typical ice build up inside windows comes from many things. 1) shades or blinds trap all air between andcold air from outside makes it freeze. 2) You need air circulation to the interior glass, dead air flow allows it to freeze or condensate. 3) high humidity in your room. I have installed windows for the past 30 yrs and ALL windows including the very best will do the same thing. First try opening the blinds or shades, allow air to circulate against the glass. Check humidity level in the room. Place a fan slow moving in the room to circulate air and you will immediately see the condensation disappear. You have to remember, if the glass is covered by blinds, shades or curtains and it is 68-70 degrees or so in the room and it is much colder outside it will create a dead air space and cold air will turn to water leaving you with condensation or if cold enough ICE. Hope this makes sense. GregC, 30 yrs. in the biz!