The absolute best way to run the ductwork above the roof is to use r8 insulation on the ductwork internal and build a doghouse outside the ductwork with minimum r30 insulation on sides and top of duct.
How to cover ducting on roof.
Cut the hole for the duct attach it then install the roof cap.
Pull the insulation over the duct and tape that.
If the ceiling is angled use a sliding t bevel to measure the angle and transfer it to your 2 by 4 s.
Locate studs in the vicinity of the ducts with a stud finder and mark the center of the studs using a long level and carpenter s pencil.
Screw the ductwork together with 1 4 in.
There are many ways to cover an unsightly ceiling whether it s genuinely ugly or you just want a change.
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.
Sheet metal screws and seal the seams with aluminum faced duct tape not regular cloth backed duct tape.
In a modern home in which the beams are a new addition this is a great way to get a rustic look.
Tack nail it in a few places so it stays where you put it.
Ducting can be run seamlessly across an entire room covered beautifully with faux beams.
Then screw the ply to the roof deck.
Then just connect the feed duct to it and put a few short screws through it and wrap it with aluminum tape.
2 fit the tapered end of the duct collar firmly.
Some of these projects are economical and others are more of an investment.
Duct temp gain when inside doghouse with r30 is less than 5 at 50.
The job requires a few hand tools a reliable ladder and the ability to work on a roof.
For ducting to be efficient it should be large enough to match the power of the blower and kept as straight and short as possible.
Before ducting your range hood to the outside you will want to consider the shape length and size you ll need as well as the size of your roof cap.
So the path you take to cover your ceiling depends on how much you re willing to spend and your own personal taste.
1 position an extension ladder at the edge of the roof in line with the rain cap that will be replaced.