Ceiling Box Suggestions

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IHMan

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Oct 21, 2010
26
CT
I will be terminating my pipe through a ceing then through a sloped roof. Since it is against the wall I believe a box that is 24" tall will be enough to go through the ceiling and to the underside of the roof (allowing for 18" of clearance). Due the boxes come with an internal support? If the roof protrusion is at least 2 feet and 2 feet of pipe inside the box, I think some other form of suppot would be needed. Also any sugestions on a brand? Thanks for your help in advance.
 
You will need to frame in a support either at the ceiling or just below the roof deck. The box then fits tight in the framing and it gets attached with screws from inside the box.
 
You will need to frame in a support either at the ceiling or just below the roof deck. The box then fits tight in the framing and it gets attached with screws from inside the box.
Thanks Webby, got it, but will the box itself be able to support 4-5' of pipe?
 
Thanks Webby, got it, but will the box itself be able to support 4-5' of pipe?
Typically they will support up to something like 40' of pipe. No worries at all with 4-5'.
 
If the stove clearances or rafter placement makes closer than 18" to the wall work better, consider going to double-wall stove pipe. It has a clearance of 6". Also note that most stoves are tested and work best on at least 15-16' of total flue system. There are exceptions though. What stove will be installed here?
 
The silver class A chimney pipe is entirely supported by the ceiling support box which is attached to the ceiling rafters in both of my current installations. There is nothing else above or near the roofline that aids in support. You can go up on the roof, hug the chimney, twist CCW, and lift the whole chimney out of the ceiling support box and walk away with it.

The ceiling support box also supports the weight of the stove pipe hanging below though some of that load is often placed on the stove itself.

As BG suggests, you may be able to move the ceiling support box closer to the back wall by going to double wall pipe and gain back some floor space otherwise wasted. The double wall pipe is superior in performance and durability.

Oh and you may find that as you slide your ceiling support box back that it hits the bottom of your roof decking. You can trim the big ceiling support box to match the roof contour so long as it fits tightly enough to prevent insulation from falling in. You can also drop more of the ceiling support box into the room, it has a minimum drop of 2 or 3".

For clarity, here's a photo of the last ceiling support box that I installed.
 

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There are ways to mount a class A chimney to the roof decking but they don't use the ceiling support box. The roof flashing (cone) is in no case used to support the weight of the pipe.
 
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