Note: Originally posted in "Builders" Forum - no takers. Does anyone have any unusual ideas for some sort of old fashioned bolt on an unglazed composite uPVC door? My elderly neighbour is getting a new back door but wants the peace of mind of bolting the door from the inside overnight. The double-glazing salesmen try to assure her that the new Euro cylinders are so good that she doesn't need .... ya de ya de ya. She wants a bolt or something else that she can see and touch. She'll have a chain but that's not enough for her .... she knows that a small bolt cutter can be poked through the partly open door. We all know that anything screwed to the plastic will: a/ fall off b/ invalidate the warranty.