Business ProfileforFibertec Window & Door Mfg

We purchased windows for our new house in 2005 and have had issues from year 3. I have been in contact with Fibertec since then and tried the fixes that they suggested. The last few years have led to house damage and insurance claims. 3 of the window frames have failed causing water to leak into the wall. I currently have most of the windows taped closed with packing tape because they will not close correctly and lock. The frames are sagging and causing the opening to be tight enough we can hardly get the windows open. This caused most of the locking mechanisms and cranks to fail. The warranty states lifetime on the frames and we have had this issue from the 3rd year after installation. Contractors that have looked at the issue all ask about the frame warrantee because they all think it is frame sag and frame failure. Even normal sized single casements won’t close correctly. Some of the larger combinations have a visible 1/4 inch sag at the bottom of the transom. I have send pictures, videos, and sent a copy of the purchase order with a description of the issue next to each window. The response stopped before Christmas. The service manager was to take all of the info to his manager but no response since. Please advise with my next step. I need to put an order in for new windows and wish to not have Fibertec windows reinstalled in my house.