Why not a square hole in roof? Ideas?

[MAD MARK]

I've run into planning stage that seems to be special instance. I have a 4/12 pitched garage and plan on installing stove in the corner.

I have 11" from truss bottom edge to roof pitch. Putting the support box 2" down my 11" box isn't high enough to go completely to roof. Normally not a concern i see but my garage is insulated on the ceiling.

Trying to figure it out, I was going to make a frame out of plywood to extend through the roof which I was going to cut square. That way I could seal off the supportbox/framing and then insulate around it on the ceiling. Any thoughts on why not to do this?

This is what it would kinda look like going into the roof. Pretty much to sum it up, what would be wrong with a square hole as opposed to a round hole if clearances are met?

 

[bholler]

That is fine as long as that plywood stays outside the 2" required clearance to combustibles. Some companies make extension sleeves for thier boxes as well

 

[MAD MARK]

That is fine as long as that plywood stays outside the 2" required clearance to combustibles. Some companies make extension sleeves for thier boxes as well

Maybe I'll check that out. I figured I have some spare flashing from doing the roof this past year I could mold something up. I bought the "kit" from Dura vent and it only has 11" box. Need at least 18"

 

[bholler]

Maybe I'll check that out. I figured I have some spare flashing from doing the roof this past year I could mold something up. I bought the "kit" from Dura vent and it only has 11" box. Need at least 18"

That should work fine

 

[HomeinPA]

Does your support box even need to go through the roof? I'd assume you're using some type of roof flashing on the roof which would be outside the support box so if it's properly sealed and flashed it wouldn't be an issue. Another thing I'm assuming is that you've secured the support box along the bottom cord of the truss so.....

 

[bholler]

Does your support box even need to go through the roof? I'd assume you're using some type of roof flashing on the roof which would be outside the support box so if it's properly sealed and flashed it wouldn't be an issue. Another thing I'm assuming is that you've secured the support box along the bottom cord of the truss so.....

I think he is doing that instead of using an insulation sheild we do it pretty often when near the bottom of the roof. But we use ventis and just get the box extension

 

[xman23]

So your saying the box goes up through the roof,and you shingle and flash around it. The you need to close it off with the chimney coming out. Wouldn't the standard roof kit be easier.

 

[MAD MARK]

I think he is doing that instead of using an insulation sheild we do it pretty often when near the bottom of the roof. But we use ventis and just get the box extension

You have it right. My roof is too close to the truss to use the shield. I couldn't find any extensions for Duravent and figured sheet flashing would work.

And Xman, my roof is already done. What makes this different from anyone's that I seen on here is my roof is insulated, not the attic.

 

[HomeinPA]

You have it right. My roof is too close to the truss to use the shield. I couldn't find any extensions for Duravent and figured sheet flashing would work.

And Xman, my roof is already done. What makes this different from anyone's that I seen on here is my roof is insulated, not the attic.

But you're still using a roof flashing up top right?

 

[MAD MARK]

But you're still using a roof flashing up top right?

Yes. I'm sure it could be done without it, but why risk it. I bought the Duravent through the roof kit.