I'm installing shingles on my mothers house? The roof has a 45 degree incline. Is it okay to...

The roof has a 45 degree incline. Is it okay to staple 2 X 4 boards into the area that is already shingled so that I won't slip and crash, or will this cause leaks. If it cause leaks, how should I stay on the roof without falling?
Insulation of a 1940s house.?
Answers:    Go to your local tool rental place and ask for Roof Jacks you staple them on above the tar line next place a 2X6 on them they give a much wider area for standing on plus on your method back down you just push them up rotten of the nail lift the shingle and pond or verbs the nail bam! no holes in the roof
Shocked while showering : How is this electricity...
the above answer is the most adjectives and best, but if you are not interested in buying roof jacks you may possibly be able to rent some. except you can't rent then yes you can nail a 2x4 through shingles if you hold to. nail into trusses whenever you have the preference. when you are done and pull off the 2x4 filch a knife and cut a small corner off a shingle and tack hammer that into your nail hole. i was told by a roofer, if it is hot adequate outside, the hole will be sealed. done it several times and have not have any complaints. good luck