1. Highly durable PVCu Constructed with 3-chambers, the profile allows separate drainage and reinforcement. All frames measure 70mm from front to back allowing the replacement of traditional 3" timber frames with the minimum of 'making good' remedial work. The PVCu system is also bevelled to provide a slimmer, more attractive look. Manufactured to BS 7413, the British Standards for PVCu window extrusions, the profile carries a full 10-year guarantee against discolouration and degradation.