Few years ago, the basement bathroom tub and "sanitary" tub in the
laundry room were clogged. I saw the plumber clear the bathroom tub
clog with a snake. Didn't see how he cleared the laundry tub but he
spent some time on the roof.

Now the basement bathroom sink needs to be unclogged. I was thinking
about snaking it.

Do I have to get on the roof first, and, if so, what procedures should
be followed? Thanks again for your help.