Butyl putty tape on a roof vent

[oakinteriors1]

The 4 screws on the interior trim piece are not going to have the pulling power to create a good seal...I read somewhere on the forum to add screws to the outside flange ....

[aggie79]

I didn't use butyl tape to install my Fantastic Fan. It came with a foam gasket. I used the gasket but I also used sealant around the perimeter and in the screw holes to prevent water intrusion.







In the above picture, it only shows corner screws installed. I did install additional perimeter screws where the hole bosses were cast into the resin flange. The screws were tightened just enough to make the fan snug to the roof. The foam gasket makes the fan sit "proud" of the roof. I later came back and put a bead of sealant around the perimeter of the flange between in the gap between the flange and the roof.