There is a debate raging over vinyl and fiberglass windows. Over which is the best choice. While generally, both windows are improvements over their predecessors. Each may offer advantages like improved maintenance benefits over the wood window, like no need to paint, and more.

But before checking into specific manufactures, have the measurements of your window openings and make sure any windows in question can be made to be set in your style openings (replacements usually have no outer tabs for mounting).

Vinyl is made of extruded pvc, polyvinyl choride, a material that has made forming these types of windows easier that former methods. Vinyl windows have varying thicknesses, usually corresponding with their quality. The better ones have welded mitres at the corners while some of the cheapest don't even have weep holes at the lower outer tracks, trapping the water. It never pays to go with the low end, some fail and fall apart within a year of two, while at the same time, reputable vinyl might outlast windows by other manufacturers that are supposedly higher ratged. Vinyl is less expensive that fiberglass and justifiably so.

The windows may be framed throughout in vinyl, vinyal clad, or split vinyl to wood (however one problem with vinyl clad is that once the vinyl manages to crack, moisture infiltrates and starts to decompose the wood.

An argument against vinyl windows is that they are quicker to crack and fail than fiberglass -- when placed in service around temperature extremes.

Fiberglass will cost you more, no doubt, and don't be surpised if they come at a 20% to 30% premuim. Though highpoints of fiberglass should translate to a more uniform expansion and contraction from weather changes and they are almost always stronger in their construction.

Some fiberglass models have insulation cavities for thermal efficiency that also eliminates the prospect of rotting wood. Although some of the better vinyl versions have integrated this as well.

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Whichever window you decide to go with, consider where you live and the hot and cold conditions the windows will have to endure. Stick with a proven name and model, and stay away from manufacturers that have just entered the market, as many tend to come and go, leaving the prospect of warranty coverage left behind. So...

Look at the warranties and see what specifically the product is warranted against and what is exluded. Including all parts, installation of the new window, and liability for damages incurred from a faulty window.A large number of the more economical-minded replacement lines fail within the first year and many homewoners end up getting stuck. Another point is if the warranty is transferable to a new home owner.

Usually first to fail is the glass seal (internal chamber fogs and discolors).

Remember, a failed window causes loss of heating and/or cooling, much of the cost of replacement is in the installation, and when water enters the home, the faulty window might be the least of your woes. So windows are an item it never pays to skimp on.