Looks like I’m gonna need to tackle this small job myself. When we got a new roof recently they installed the 10-inch roof jack we need for our exhaust hood. I have enough duct and 2 swivel joints to connect. Looking from the attic, I have a hole in the roof, no round stub to connect to. What is the final connection to the jack on the underside of the roof supposed to look like? I assume the duct goes up into the metal roof jack, through the roof decking a couple of inches. How do I secure this connection, though? Just tape? There’s nothing to put a sheet metal screw into. Metal hanger strap screwed into a stud and into the duct?

This post was edited on 1/28/23 at 4:40 pm

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Posted by gerald65

Moss Bluff, LA

Member since Jul 2020

710 posts

Posted on 1/28/23 at 6:18 pm to turkish

A picture would really help to understand what you are trying to do.

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Posted by MikeD

Baton Rouge

Member since Jan 2004

8401 posts

Posted on 1/28/23 at 10:03 pm to turkish

There are definitely codes about this

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Posted by LSUengr

Baton Rouge

Member since Sep 2005

2616 posts

Posted on 1/28/23 at 10:53 pm to turkish

Yes, if using hard duct pipe, stab it into toof jack. Then wrap with metal duct strap and screw to roof supports on either side. Avoid screwing into duct if possible. Will collect grease since it protrudes into duct. Not a huge issue of you have to screw into duct but would avoid if possible.

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Posted by MikeBRLA

Baton Rouge

Member since Jun 2005

17192 posts

Posted on 1/29/23 at 6:35 am to LSUengr

quote:
if using hard duct pipe

Isn’t this required? I didn’t think you could use flex for kitchen exhaust.

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Posted by Ziggy

Member since Oct 2007

22099 posts

Posted on 1/29/23 at 6:52 am to MikeBRLA

HIJACK -- any recommendations for a local BR / Northshore company that could cut a hole in an existing roof and install new duct roof cap for new hood duct? Tiny job and I'm sure there would be a minimum charge, but do not want to tackle myself and would rather leave to a professional. This is for my parents home.

Thanks all!

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Posted by MikeBRLA

Baton Rouge

Member since Jun 2005

17192 posts

Posted on 1/29/23 at 7:15 am to Ziggy

Any roofer can take care of that.

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Posted by turkish

Member since Aug 2016

2378 posts

Posted on 1/29/23 at 5:28 pm to MikeBRLA

Will definitely be using (and cussing) hard duct, not flex.

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Posted by turkish

Member since Aug 2016

2378 posts

Posted on 1/29/23 at 5:29 pm to MikeD

Should be easy to find the standard way to do this, then, but here I am.

To summarize, I guess what’s unclear is what supports the vertical ducting sticking up into the roof jack. Is the metal strapping compliant?

This post was edited on 1/29/23 at 5:32 pm

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Posted by LSUengr

Baton Rouge

Member since Sep 2005

2616 posts

Posted on 1/30/23 at 10:33 pm to turkish

quote:

Isn’t this required? I didn’t think you could use flex for kitchen exhaust.

New construction, yes. After the fact construction, your call. Millions of houses have flex hood vent piping and are perfectly fine. It wont last as long and will clog faster. Wasn't advocating its use, just clarifying my comment.