I need some advice for keeping my runs straight when going around gables. In spite of regular measuring, my runs seem to drift when I have to go around mid-roof gables.
You mean dormers not gables right? You need to measure up one side of the dormer to the peak of the dormer. Then do the same thing on the other side of the dormer. Now pull your first line that goes OVER the top of that dormer. There are times when you need to mark from the ridgeline down but not many. What you may like to do is pull a tape measure from the ridgeline when you get about 3/4 up the roof to make sure your lines are straight with the ridgeline. If it’s off by a little bit you can usually split the difference and run with it. If it’s off bad due to carpentry you’re going to have to take the difference between the two lines and divide it by let’s say 1/8th and figure out how many lines you need to adjust on one side to get straight with the ridge. Hope you understood that, lol.
It seems as though the valleys cause the runs to climb at the ends.
Pop all your chalk lines out first on your roof deck. When you lay the valley shingles it is usually easiest to run up the valley at aprox a 45 degree angle or “staircase”. The trick here is to NOT lay your first shingle into the valley like you want to. Lay your first shingle that would fall next to your valley first and then butt the shingle that goes into and across the valley next. So you’re laying 2 shingles and then moving up to the next row above it. If you try and lay your first shingle into the valley it will cock every time.
Additionally, what is the cleanest way to cut a closed valley. I hook blade on cold shingles does not give the best finish. Thanks.
Hook blades are best for most shingles when it is warm out but in the colder weather you need an old pair of tin snips/metal shears. Ones with long blades like the “Andy” snips make nicer cuts.