Man....I fell like we have all read this same thread before.
I like Fiberglass windows. I have nothing against them. They are easy to make, costly to buy and look and operate well. Doc, I think we can agree to disagree on some things. The reason why I do not like the way your information is presented, is, it has strong bias. You quote fiberglass window company websites. Look up life expectancy of vinyl windows. Most of the web sites have 20-30 years listed as the life expectancy.
If you statistics are correct, why does vinyl always have a better warranty than wood....and the same as vinyl. (if sold by a company that sell vinyl and fiberglass. Marvin only has a 10 year warranty on the fiberglass...why?) If the glass holds up better in fiberglass, than why only a 20 year warranty? I am not saying that vinyl is better. Fiberglass has much better structural properties. The thermal properties are better too. (though not worth the cost upgrade of a fiberglass window) They can be painted. That is why I would sell them. They can be painted where vinyl is painted against most manufactures suggestions. They are usually extruded a shade of light brown or white. Vinyl usually has at least a 20 year warranty from a poor warranty to a lifetime warranty. On the West Coast, if you do no have a lifetime warranty on the vinyl and at least a 20 year non prorated glass for vinyl, good luck selling the window. The contraction and expansion of vinyl described by fiberglass sales people makes it sound like glass is crushed by shrinking frames and then pops out by expanding frames. Post a picture of a home or IG damaged by contraction and expansion of a decent vinyl window. That would put that discussion to bed and I will concede your argument. I have yet to see one.
Again, fiberglass is a good product. Structurally, I do not like mitered corner. They can break, pull apart etc. (I think of aluminum mitred corners, and see them after years allowing water. Not says fiberglass will, but I can envision it)
JScott: I saw the movie, good movie. Greenpeace does a good job in making sure our environment is protected.
If that is the reason not to sell a good window are a good price and start forcing consumers to buy other types of windows, we should all install wood window. Wouldn't you think? It is a renewable source and is much more eco friendly than Fiberglas.
All kidding and sarcasm aside, all window types have their place. I just get sick of people saying one is better than the other using bad facts (or blown out of proportion facts) that amount to scare tactics for sales people to steer them toward one window.