Abstract: A decorative arch form including a pair of side sections, each of the side sections having two edges substantially perpendicular to one another, integral flange members extending from the perpendicular edges of each of the side sections with lines of reduced thickness at the junctures of the flange members with the sections, the side sections being disposed in a substantially parallel spaced relationship with the flange members of one side section in alignment with the flange members of the other side section, a decorative facia section connecting corresponding edges of the aligned side sections and extending from the far ends of the aligned flange members of the parallel side sections to the far ends of the flange members which are perpendicular thereto.