Cathedral ceiling with exposed beams - chimney support box

[cneg34]

Well, I'm looking to replace a very old and inefficient wood stove with brand new.
Question about this current setup and how to support new chimney, that will mate to Selkirk DSP 6" double wall pipe that I already own (ideally).

The roof support beams are exposed and above the beam is the ceiling paneling which I plan to keep. Above that I assume is roof deck and several applications of shingles. We do plan to re-roof the structure eventually with a metal roof with a layer of rigid foam insulation under the metal roofing.

Picture is of existing stovepipe exit thru ceiling. Pipe measures slightly over 8" circumference (OD) so I assume 8" single wall pipe, up thru shown assembly. Same circumference on existing steel chimney. I plan to scrap the pipe/chimney, but will be left with existing hole.

What are the options for supporting thru this ceiling? Is internal framing required and if so, to two beams to support something like the 6" Selkirk Support boxes that provide the 2" clearance?

 

[stoveliker]

If the chimney pipe is also 8" OD, your actual inside diameter will likely be 6" for the chimney pipe.
I hope it's the same for the stove pipe in the pic. That is good, because 6" is more common, and it means it's double wall, which is good too. Many stoves run on 6" ID pipe.

If the chimney needs to be replaced, then I'd see if you can find out the brand of the support box, and go with chimney of that brand. (Others will know more about this.)

 

[cneg34]

thanks Stoveliker! It appears the install of the stove was likely circa 1970s. It's a Sears & Roebuck 143-433! We bought this place and it's still got the 1970s shag carpet. It will be off to the scrap yard soon.

I was presuming I'd start with a new chimney pipe as well given the age and uncertainty of it all. But I think I'll crawl up on the roof and give it a good inspection to see what I can figure out in terms of the chimney and support box.

If I end up with a new chimney, am I looking at framing to support a new box on the inside of my ceiling as my only option?

 

[stoveliker]

I don't know enough about support boxes, so someone else will have to help with that.

1970s shag carpet. If you keep it a decade longer, maybe it'll increase to proper antique value 😂

 

[Crummy]

When you say "ceiling paneling" what is it? I just recently had all new pipe installed and my roof is like yours. My "ceiling paneling" is tongue and groove 2x6. Above that is spray foam, air gap, sheeting and shingles so the 2x6 tongue and groove is the structure. The old chimney was supported by what the installer called wings that were screwed to the ceiling. New chimney is supported by a box screwed to the ceiling 2x6. If yours is actually paneling then it will be different.

Old


New

 

[cneg34]

That's another good question, I don't know what we will find above what is certainly tongue and groove boards. It's half the cabin, the other half having an attic space and truss supported roof deck. I would not expect to find any spray foam or insulation of any type.

 

[begreen]

thanks Stoveliker! It appears the install of the stove was likely circa 1970s. It's a Sears & Roebuck 143-433! We bought this place and it's still got the 1970s shag carpet. It will be off to the scrap yard soon.

I was presuming I'd start with a new chimney pipe as well given the age and uncertainty of it all. But I think I'll crawl up on the roof and give it a good inspection to see what I can figure out in terms of the chimney and support box.

If I end up with a new chimney, am I looking at framing to support a new box on the inside of my ceiling as my only option?

This will almost certainly need to be replaced to meet the current UL 103-HT standard for Class A chimney pipe.

With a cathedral ceiling support box, you have the option of attaching it to the roof vs boxing it in. This is done by creating an attachment flange from the portion of the box that extends above the roof. Or you may be able to anchor it securely to an adjacent joist and create a box collar to attach the other side(s) to.

 

[cneg34]

This will almost certainly need to be replaced to meet the current UL 103-HT standard for Class A chimney pipe.

By "this" do you mean the box/support or the entire chimney system? Woodstove and stove pipe is already "for sure". Thanks!

 

[begreen]

The entire chimney system. ^See the additional info I added about using a cathedral ceiling support box. ^

 

[begreen]

Older pipe was often rated at 1700º. New Class A chimney pipe for a wood stove has to have better insulation rated at 2100º. Professional eyes on site may be able to verify this better.

 

[begreen]

Can you post a picture of the chimney that includes at least one full section of pipe and the cap on top?

 

[GrumpyDad]

Well, I'm looking to replace a very old and inefficient wood stove with brand new.
Question about this current setup and how to support new chimney, that will mate to Selkirk DSP 6" double wall pipe that I already own (ideally).

The roof support beams are exposed and above the beam is the ceiling paneling which I plan to keep. Above that I assume is roof deck and several applications of shingles. We do plan to re-roof the structure eventually with a metal roof with a layer of rigid foam insulation under the metal roofing.

Picture is of existing stovepipe exit thru ceiling. Pipe measures slightly over 8" circumference (OD) so I assume 8" single wall pipe, up thru shown assembly. Same circumference on existing steel chimney. I plan to scrap the pipe/chimney, but will be left with existing hole.

What are the options for supporting thru this ceiling? Is internal framing required and if so, to two beams to support something like the 6" Selkirk Support boxes that provide the 2" clearance?
View attachment 298911

If I were you I would check to see what you have on the roof. What type/age the chimney pipe is. If it is as old as the black stove pipe inside, I would budget to replace EVERYTHING. The stove, the pipe and the chimney. Dont mix stove pipe/chimney manufacturers, and you should be good to go. Once someone takes that chimney out and inspects inside the flashing, they will see what you have to work with as it relates to a support box.

 

[stoveliker]

While that news may be disappointing, the good news is that if you replace it with a stove that (efficiency) qualifies for the tax credit, all those other components will also give you a tax credit.

 

[cneg34]

Can you post a picture of the chimney that includes at least one full section of pipe and the cap on top?

 

[begreen]

That definitely needs a full replacement and a much better job done with the new flashing.

 

[GrumpyDad]

That definitely needs a full replacement and a much better job done with the new flashing.

Flashing....you see flashing? Good news is, the hole cutout for the new flashing will likely be as large if not slightly larger than the current 'flashing'.
bad news is, that pipe, that cap, that storm collar with 9 pounds of probably solid as a rock goo on it, will all need to be replaced. And Im sure a ceiling support box will be required that matches up to the chimney system and the stove pipe.

 

[Riverbanks]

Judging by the size of that exposed beam, you should have a rafter system above that v- groove board ceiling. Could you drop a string down the pipe with a weight on the end, stop it in the stove, mark the string. Measure the string, then measure roof top pipe and interior pipe and see what the difference is in measurements, that could tell the thickness of the roof system

 

[BKVP]

The other problem with old chimney systems is not knowing how many if any chimney fires took place. A coworker here had his inspected "for safety reasons" at the time of purchase and the insurance company paid for the replacement. However as @stoveliker pointed out, the 25D Tax credit of 26% will apply so long as you get it installed by 12/31/2022 with a tax credit compliant model. Remember, if this seems burdensome, the tax credit covers labor, venting, stove etc.