How often should you replace a skylight? Skylights should never need to be replaced if properly maintained. Realistically, that is something that should never have to be replaced unless the neighbor's kid...
Realistically, that is something that should never have to be replaced unless the neighbor's kid sends a baseball through it.
When insulated glass was first introduced, they had a few failures where the hermetic seal around the glass would fail and you would get condensation and things of that nature. That's where you get that milky looking glass. Now most glasses are guaranteed for 10-20 years against seal failure. You really shouldn't have to replace them at all. There are also self-splicing windows in which the bubbles over a period of time tend to milk up pretty bad. Eventually, the possibility for a leak is pretty high as well. It's important to look at the quality of the window you get.
The big issue that comes into play is that people say they want a maintenance-free window. There is no maintenance-free window. Everything requires periodic adjustment and maintenance like washing. Let's say you are cleaning your window and you notice a crack in the sealant at the bottom of the window. You need to address that or you will have a problem. You could also have a problem with the window rotting out due to lack of maintenance, and most warranties will not cover that.
