Weather proofing Chimney - gabled roof

[Ken524]

We have decided on a gabled roof over the oven. For roofing material I'm thinking about standard shingles to match the house or a metal roof (several neighbors have pole-barns with green or red metal roofs which would look nice)

How do I transition the Duratech pipe through the top of the gable roof and weatherproof it? Duratech sells flashing for angled roofs and flat roofs, but nothing for a chimney that goes through the top. I attached a picture to better explain my question.

Also: If I want to do a shingle roof, what material do I use for subroofing? I don't really want to use plywood due to the heat potential, and I'm not sure if I can nail shingles into Durock/Hardibacker. Any ideas?

Thanks!

[wlively]

Re: Weather proofing Chimney - gabled roof

Ken

I did pretty much what you are asking.

I used OSB roof decking (tech shield from Home Depot) on mine. As long as you have a good insulation barrier ( I have 4 different layers) then there are no worries about the roof. As an added precaution I used the tech shield because of the foil covering, foil side down. Probably not needed, but it was cheap insurance. Try putting your hand on the shingles on a hot summer day, OWW! It is alot hotter than the inside of my oven will get.

You are right about the chimney pass thru, I could not find one anywhere either, so I made one. I cut the wood so it would be 8 inches away from the chimney pipe. Then I used metal flashing to cover most of the exposed gap, leaving about 1/2 inch space between the chimney and flashing (being cautious again). I should add that while doing the curing fires I put my hand on the outside of the Duratech to see how hot it would get. That Duratech is great stuff as it did not get more than warm. Then down went the felt paper. Next, I cut some scrap cement board onto 4 rectangular pieces, two notched for the peak of the roof, to make a box (fake chimney) around the pipe, if you can imagine what I mean. Screwed the "fake chimney" to the roof. Bought a tube of fire barrier sealant and filled the inside gaps of the box. After that set-up I finished filling the chimney with the LaHabra Wall (stucco scratch coat) till I had it flush on top and then sloped it just in case any water from rain got under my cap. Then shingle and stucco the outside of the chimney.

Held up great so far.

I hope that is a good explanation.

[Ken524]

Re: Weather proofing Chimney - gabled roof

Excellent explanation. Thanks! I found your pictures on your thread. That helps a lot.

[Guerito]

Re: Weather proofing Chimney - gabled roof

Ken,

Just another thought Ken…You could buy 2 transitions, cut them in half, to give you the peak angle, and have them soldered back together.

The shingles, I imagine, could be glued with a Liquid Nails type waterproof caulking. I think that would hold them to the hardiacker board.

Guerito

[Ken524]

Re: Weather proofing Chimney - gabled roof

Thanks Guerito!