Looking for some info on adapting a composite door's uPVC frame. Basically I need a front door as my old uPVC door is knackered but in a tight budget. I've found a door which is an ex showroom display model which is ideal in width and also has a top light integral to the frame which I need (properly mitred in). The only issue, it's a few cm too tall. I need to cut the top of the frame down making the top light narrower to accommodate the opening. The glazing for the top light isn't included with the door anyway so I'll just get a piece made to measure after adapting the frame. I have a circular mitre saw and have fitted upvc frames before. It should just be a case of separating the top part and cutting the 2 side pieces down. I'd like some info about how they are joined and fixed together before attempting it so I can plan it out before hand. How are the mitred sections of a uPVC frame fixed together? In guessing some kind of internal metal framework is used to strengthen the joint? Is this possible to do without specialist tools?
