Flashing fireplace chimney flue


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Old 03-25-07, 03:01 PM
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Flashing fireplace chimney flue

I have a 12" diameter chimney flue through rough decking. I am looking for a pre-fab flashing that fit over this flue pipe and fastens to the roof deck. I checked the big box and found Supervent makes pieces like this for 6" and 8" flue pipes, but nothing for our 12" incher. If anyone knows a decent source where this can be found, or an alternate method of flashing, please let me know.

Just for reference, this is for a fireplace. Around the flue pipe on the roof is fitted a sheetmetal fake-chimney. It's painted to look like brick, but let's face it, it's not fooling anyone.

thanks
 
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Old 03-26-07, 12:05 PM
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update

just an update in case anyone else is working on a similar project.

I was a bit confused in that the nominal flue diameter is the diameter that actually flows gas (inner pipe). The of the outer pipe varies by manufacturer such that it complies with UL class A solid fuel flue piping standards. Now that I know what I'm looking for, I contacted some local fireplace shops and will stop is to see what they offer. I did take the prefab chimney apart last weekend and repaired some rusty areas - replacement units are not cheap and I don't feel like framing up a new chimeny from scratch. I'm almost temped to fab the sheetmetal for the flashing myself, but I don't know how to make the hemmed joint where the portion surrounding the flue pipe meets the flat roof deck flange.

If you don't hear from me for a while, it means I fell off the roof and am eating my meals thru a straw.
 
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Old 03-26-07, 01:01 PM
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A sheet metal shop can make you a roof jack for it. If you want or make it yourself. You make say a 12" high pipe that will slip over the flue pipe. Take a flat sheet about 2'X2' . Cut out the center to fit the pipe tight. On one end of that pipe cut up in it 1/2" every 1/2" bend every other one out at a 90o. put the pipe in the hole in the sheet. Then on the under side bend over all the other tabs 90o so its all flat. Then just solder it all up and you have a roof jack.
 
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Old 03-27-07, 11:25 AM
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Hey, that sounds pretty good. I'll play around with some cardboard and see if I can get the patterns straight. Making the roof jack (that's what we're calling the flashing, right?) myself has the added benefit of allowing me to customize it for my roof slope. Plus I get to solder a bit, which is fun.

Here's a question - I see sheetmetal for sale at the big box store meant for duct work, and then I see galvanized sheet for sale elsewhere. The ductwork sheetmetal is much less expensive even though it is of the same gage. Is the finish on the ductwork sheeting appropriate for use on outdoor stuff? Looks to be aluminized or galvanized. Hard to tell.
 
 

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