First thing is all shingles and shakes should have triple coverage when they are put on. For example, a 18" shakes should only lay at a maximum 6" exposure, because 6 × 3 is 18. (That is 6" exposure times triple coverage “3" equals a 18" long shake)
That is why all our 18" shakes are figured at 6" exposure to make a square (10’ x10’ area) It takes 5 bunches to make a square of 5/8" × 18" shakes. You will see others on the web that lay 8". (Red cedar or Mid-Western White cedar sell their 5/8" × 18" shakes with a 8" exposure.) That should alarm you right off quick. If the exposure is too high, the shakes will curl up on you. Also, if the shakes are priced per square at 8" and you lay them at the correct 6" exposure you are going to need more squares to do the job, making the prices at Dow’s lower then the others.
Also a 24" shakes should only lay 8" exposure (8" × 3 is 24") All our 24" shakes have a 8" exposure and it takes 4 bunches t make a square (10’ × 10’ area) Most all Red cedar and Mid-Western White sell a 24" shake with a 10" or 12" exposure. Again that is wrong at 10" or 12" you can’t get triple coverage.
Dow’s Eastern White Shingles & Shakes is here to help educate people so they can make the best choice for them when purchasing shingles and shakes.