So i don t know what size to make it and i think it depends on how the duct is attached to the roof jack.
How to connect ducting to a roof jack.
The roof jacks i ve seen are tapered wider at the bottom than the top.
Typically the duct passes through the roof jack with a rubber flange at the top of the cone of the roof jack making a water tight seal against the side of the duct.
Installing the roof jack 1.
Typically the duct passes through the roof jack with a rubber flange at the top of the cone of the roof jack making a water tight seal against the side of the duct.
Apply caulking compound on underside of roof flashing to form a continuous strip at least 3 8 wide around the underside of the perimeter of the flashing see figure 20 or figure 21 page 13.
The three screws will prevent the two ducts from moving and separating at the new seam.
2 fit the tapered end of the duct collar firmly.
Insert two additional screws along the seam with equal spacing between the three screws.
Then screw the ply to the roof deck.
I can t find a roof jack off the shelf anywhere that will fit that large a duct so we might end up getting one made.
Then just connect the feed duct to it and put a few short screws through it and wrap it with aluminum tape.
So for your 10 diameter duct your custom roof jack should have a 10 opening at the top of the cone.
So for your 10 diameter duct your.
Direct the crane operator to position the unit on the platform with the outlet port at the side facing the direction of the duct riser at the roof.
Tack nail it in a few places so it stays where you put it.
Insert a 1 2 inch long self tapping sheet metal screw at the location where the two ducts overlap to provide a solid connection.