Figure 2-53.—Jack rafter framing diagram.The best way to figure the total runs of valley jacksand cripple jacks is to lay out a framing diagram andstudy it to determine what these runs must be. Figure2-53 shows part of a framing diagram for a main hip roofwith a long and short valley rafter gable addition. Bystudying the diagram, you can figure the total runs ofthe valley jacks and cripple jacks as follows:The run of valley jack No. 1 is obviously the sameas the run of hip jack No. 8, which is the run ofthe shortest hip jack. The length of valley jackNo. 1 is therefore equal to the common differenceof jacks.The run of valley jack No. 2 is the same as therun of hip jack No. 7, and the length is thereforetwice the common difference of jacks.The run of valley jack No. 3 is the same as therun of hip jack No. 6, and the length is thereforethree times the common difference of jacks.The run of hip-valley cripple Nos. 4 and 5 is thesame as the run of valley jack No. 3.Figure 2-54.-Line and actual lengths of hip roof ridgeboard.2-32
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