Sometimes the seal between the two pieces of glass will fail and in this process, condensation or other moisture can make it’s way in between the two panes of glass. Once this occurs the glass will appear “foggy” or dirty. The best solution to this problem is to have the unit replaced. This does not involve replacing the entire window frame; just the insulated glass unit needs to be replaced.
When having your insulated glass unit replaced always enquire about whether your new insulated unit will be certified and whether it will be warranted against seal failure. At First Response Glass Ltd all of our sealed units are IGMA Certified and they come with a 10 year manufacturers warranty against seal failure. The standard warranty on insulated glass is usually 5 years, so remember to ask the question and don’t settle for any warranty less than 10 years.