I have a 21' tall exterior chimney and Im getting ready to clean it and have some questions. I can clean from the bottom up but would like to get up to the top and clean the cap and screen so here's my question. I don't have a ladder tall enough to get to the top. I do have a ladder that can get me to the roof and from there the chimney is another 10 or so feet up. Is it ok to lean the ladder from the roof to the top of the chimney? Are there any safety concerns here or things I should look out for? Also am I just over thinking this whole thing should I forget about going up top and just do a bottom up cleaning and be done with it?