to fig5 7 a roof construction utilizing the principles of the invention is shown an element useful in such constructions and which may be utilized in otherwise conventional roof rafter constructions is shown in fig5 this element is in the form of an angle bracket denoted generally by the reference numeral 68 constructed in one piece of a rigid material such as metal of suitable thickness bracket 68 includes two arms 70 and 72 each having parallel side edges 74 and 76 and 78 and 80 respectively and end edges 82 and 84 respectively arms 70 and 72 are disposed at a fixed predetermined angle i e the angle embraced by edges 76 and 80 and thus by edges 74 and 78 being indicated by the letter a end edges 82 and 84 are disposed parallel to a line bisecting angle a i e parallel to slote 86 bracket 68 further includes one or more elongated through slots 86 disposed on a straight line bisecting angle a between edges 74 and 78 and between edges 76 and 80 slots 86 are wide enough to permit the end of a marking pencil to extend therethrough and make a mark on a board upon which bracket 68 is resting brackets 68 would be fabricated in a number of different angles to conform to various roof pitches e g.