You must determine the ridge length of the cricket by choosing the slope for the cricket and multiply that number by 1/2 the width of the chimney. Then divide that result by 12. Multiply the dividend by 12 and divide that result by the roof slope number. Ex. 30" chimney, 5:12 cricket, 9:12 roof. Cricket height equals 15 times 5, divided by 12= 6.25. Ridge length equals 6.25 X 12 divided by 9 = 8.334. Cricket slope along back side of chimney = the square root of 6.25 squared + 15 squared = 16.25. To lay out a cricket, scribe a line parallel to the edge of your metal 32.5" long. Scribe a line perpendicular to this line at its halfway point 8.334" high. Scribe lines connecting the ends of these two lines to create the two right triangles that will be the two sides of your cricket.
