tac422, Howdy;
First of all what is the roof made of? More precisely, is it a rubber membrane?
What year and make is the TH? Mostly in the last 10+ years they have been covered with
a rubber coating that is NOT compatible with silicone sealants. The membrane is called EPDM.
Here's a link to a Google search page that should help get you started;
https://www.google.com/search?q=RV+roof ... 8&oe=utf-8There are tapes and some other types of chalks, some self-leveling, that can help you
get-r-done.
hank
Striving for a less complicated life since 1949 ...
Every day I beat my own previous record for number of consecutive days I've stayed alive.