The downsides of Fibrex Fibrex is now the best composite material for use in windows. As a result, as compared to other window materials, fibrex-based windows have a higher sticker price. However, the total value of fibrex-based windows cannot be beaten in terms of energy efficiency and long-term value. Fibrex has some drawbacks that affect its overall cost effectiveness: it's heavy, which increases the cost of shipping and storage; it's not recyclable; and there is no way to get rid of its sticky residue once it's inside your home. In addition, fibrex can only be ordered through specialty window manufacturers, so it isn't easy for individuals to purchase them. Finally, while fiberglass looks great, it doesn't last forever - it will eventually need to be replaced if you want new windows that match your current exterior decor. The good news is that replacement windows are affordable. There are many different types of windows on the market today, from cheap vinyl to high-end wood products. You should look for replacement windows that meet or exceed the quality of your original windows. This will help ensure proper insulation and durability throughout the life of your new windows. If you do not replace your old windows, they will cause damage to your house over time. Old windows may leak air conditioner or heater moisture into the house, causing mold and mildew growth.