Get your chalk reel.
How to snap a chalk line for roofing.
First snap a line for the top of the starter course whose bottom will be flush with the waterproof shingle underlayment wsu or felt underlayment which overhangs the drip edge by 1 2 inch.
Never snap chalk lines on steel sheeting.
I too am a diyer and not a professional roofer.
Snap horizontal chalklines to help you keep the courses straight.
Then snap lines for every course or every other course.
This saved on nail holes.
Even small moisture amounts will cause chalk dust lines as well as any black or lead pencil marks to permanently damage steel surfaces.
I snap chalk lines solo by wrapping the free end of the string on a brick and pulling tight on the other end.
The line produced by the chalk snap line is fuzzy and sometimes hard to follow when cuttting along it.
Hook the chalk line clip over the nail head or screw and reel out the string to the other end point along the straight surface.
By bob vila using a chalk line is a quick way to give yourself a straight line as a building guide.
Once you have the chalk line over the second mark lift off the string and allow it to snap back onto the surface.
Snap a chalk line the next time you need to mark a straight edge as part of a home improvement job.
The chalk will mark a straight line along the surface between the two points.
Snap a vertical chalk line from the inside edge of the first shingle on the second row to the top of the roof and from the inside edge of the first shingle to the top of the roof.
3 tabs i snap the same baseline then square off that for a vertical bond line then i measure over half the width of a tab and snap a parallel line.
I snap a line for every other course.
Then hook one end of the chalk snap line to your beginning point.
When it comes to the use of chalk near steel roofing and siding the following warning should have been added.
If you have a well functioning chalk snap line you can slowly play out the line without.
If i must past a obstruction i snap a line through higher and use it as a reference point for the shorter actual lines.