Andersen Series windows and patio doors are available in deep, rich colors and are made with our unique, revolutionary Fibrex composite material..We developed a material that is x as strong as vinyl, performs better when exposed to extreme temperatures and delivers exteriors that won’t fade, flake, blister orl.*.Customer reviews on Fibrex produced by Renewal by Andersen. Window Comments. I had windows installed by them in . Every company besides them wanted to do an insert, which is when they leave the rotted frame of my window behind and insert a smaller version of the window I have, inside of that existing frame..One of the more interesting choices is the comparison between vinyl windows and Fibrex windows. As commonly advertised on the over sized mailing fliers, one well known window company routinely portrays vinyl windows as cheap, unreliable, and not worthy of your home..