Cathedral ceiling install/insulation question

[pfettig77]

When I install my Jotul 602 through the ceiling and I use the support box, I'm concerned that there will be a big ol' 15" squared area with no insulation. Is there any remedy for this or do people just deal with a "dead spot" in the ceiling? Also, should the hole that goes through the roof (sheathing and shingles) be a circle that's 2" from the pipe or should it be the shape and size of the box? Thanks.

 

[DAKSY]

Bring the insulation right up to the sides of the Cathedral support box, or at least up to the framing holding it in position.
The box has the proper clearance-to-combustibles built into it.
Cut the hole in your roof 2" larger than the Class A coming thru. I use the bottom of the flashing cone as a guide.
Set the flashing where it will finally be situated & trace the bottom of the opening onto your shingles with a yellow crayon.
Cut your opening 1" outside the layout line & you can't go wrong. Just make sure at the bottom end of the cut, your sides
are perpendicular & square so that you'll have a slot to slide the flashing into when it's inserted under the shingles...
The finished hole should look like an upside down U with a flat at the bottom.

 

[pfettig77]

Thanks a lot. That's gonna help a ton.
I have old metalbestos 7" pipe and the only flashing I found locally is for 6" or 8". I bought the 6" thinking it would fit through but it just barely doesn't. The picture is the same stuff I have. I wonder if I'd be able to cut through 2 or so of the slits to the top to make the pipe fit through?

 

[cre73]

I filled my ceiling support box with fireproof insulation from my work. We use it on our boilers. I tested the insulation before hand by taking my torch to it. Been in place 6 years now.

 

[pfettig77]

do you happen to know if that stuff is available retail?

 

[Tony D]

I filled my cathedral ceiling support box with vermiculite. Its fire resistant and you can buy a bag of it at menards.

 

[pfettig77]

Cool. This stuff:
http://www.menards.com/main/buildin...l/vermiculite-insulation/p-1485908-c-5777.htm

 

[Tony D]

Thats it!