CT gray roof sealant??

[tripletaco]

So, Ive got your basic flat roof cargo trailer. It uses galvalume roof panels with a seem every 4 feet or so. Well, my question is what is the gray rubbery sealant that is smeared on all the seams and around the edge? Is this EPDM that i hear som much about used in the RV industry? I'm installing a roof vent and one edge of the vent flange will be partially on that gray rubber. I'm trying to understand compatibility and make sure i use the correct products together.

I see that butyl tape is often recommended and is compatible with just about all materials. Would that be the way to go? If i use butyl tape is any additional caulking necessary? What about the screw heads on top of the vent flange, should those be caulked?

thanks in advance!

[tony.latham]

Take a look at this thread:

viewtopic.php?t=49731&p=925301

Scroll down to Grant Whipp's reply. He's built more teardrops than I'll ever see.

TL