Square ceiling support box question.

[toejam]

Is it ok to attach the box against the rafter?

It is a cathedral ceiling thats a depth of two feet.

I am going to frame around it above the drywall. Should I frame it under the roofs plywood also?

I find it very difficult to try and frame inside a drywall hole this is 15" x 15"

 

[begreen]

Answer to first question is yes. The support box will maintain the required class A clearances. Framing instructions are provided by the pipe mfg. Download their docs for some good pointers.

 

[toejam]

Sipmsons duravent instructions are weak.

 

[dougand3]

If I'm understanding your question correctly...the one "frame in" on the sheetrock side of joists for the ceiling support box is all you need. Don't need framing at roof decking/plywood - just a hole thru decking/shingles maintaining 2" clearance to Class A chimney. ie 6" ID chimney is 8" OD...so, 2" + 8" + 2" is 12" hole. I went 14" in mine in case it's not perfectly centered.

 

[begreen]

Sipmsons duravent instructions are weak.

Hm, I thought the Duravent installation guide did a fairly good job. But perhaps this is a unique situation. Can you put up a drawing of what the concerns are?

 

[John_M]

toejam, Simpson also makes a Roof Support Bracket which might help in your installation if you are unable to do the framing necessary to use the chimney support box to support the chimney. Frame in the ceiling support box as best you can because, as BeGreen stated, it will provide the necessary 2" clearance to combustables. Use the Roof Support Bracket to support most of the weight of the chimney. Just a thought.

John_M

 

[devinsdad]

Here are some pics of my duravent install if that helps.I used an adjustable length dvl pipe inside to stove. When I cranked the stove up to 750 in my alcove install there was no problem touching the ceiling support box for a few secs.I used a cathedral support box and it was just shy of the roof so I wrapped it with aluminum and folded the top down on top of roof. I then also used a roof support to add stability and ensure the 2" clearance . I am right at 5' above roof so I returned the arms that support over 5'. Hope these help.oh and the final pic is at startup hence the smoke.

 

[John_M]

devinsdad, Your installation is about as perfect and safe as Simpson or any codes inspector could hope to see. Well Done!

The photo of the installed Roof Support Bracket should prove helpful to toejam should he choose to install one.

Your avatar of Devin wearing ear muffs while helping dad is a great photo. You must be very proud of this future wood burner. Well done there also!

John_M