a method and system for use in forming arched openings in both concrete block and wood frame building construction . in block construction the present invention provides for the use of monolithic plant pre - cast and reinforced concrete header and arched filler combination units that is load - bearing , and in wood frame construction the present invention provides for the use of non - load - bearing pre - formed arch - filling members that could be made from recycled plastic attached to or including a lintel for overlaying the surrounding wall frame . use of the present invention would eliminate the need for labor - intensive post and beam type headers with a site - built wooden arch and thereby reduce the on - site costs currently associated with site installation of windows and doors having an arched upper perimeter . the materials from which the present invention is made would determine its load - bearing capacity . in addition to having a labor saving advantage , the method of the present invention is also costs - efficient by eliminating material waste that results from materials being incorrectly measured and cut on a job site . applications may include , but are not limited to , use in more rapidly , cost - efficiently , and easily forming openings for windows and doors having an arched upper perimeter in both residential and commercial construction .