i use a calculator and the stanley but I always have my rafter square with me, it is good if the pitch is not an exact angle. but i do like using a jig, marked up with "plumb" and "seat" to avoid errors
hi dd, problem with hiring pitch is that i am ampered by two windows on gable where new roof is going, calc done on 2.4 high side wall which is what hight of ceiling will be,to raise pitch will have to cut down on height off ceiling? i am going to use garage as workshop so could do with high ceiling
windows are always a menace (so's microsoft windows) i sort of guessed as much but wasnt sure. PS "ampered" are you a secret sparky
If you are using new double romans I shouldn't worry too much about reducing the pitch to 18.5degrees just increase the lap slightly to be sure new ones should shed water fairly well even if the pitch is slightly below reccomended.
just looked on marleys website and you can use smooth double romans down to 17.5 pitch so no worries there have to use 100mm headlap i presume this means over lapping tiles by 100mm instead of 75mm?