Nailing Fin:A vinyl or aluminum extension installed to the frame of a window or door which creates a positive seal between the window and the framed wall. commun in new construction windows..
NFRC:National Fenestration Rating CouncilĀ® -a non-profit organization that provides fair, accurate and credible energy performance ratings for windows and doors.
NWWDA:National Wood Window and Door Association. Trade organization which has established many standards related to wood window and door products.