Chimney support box on vaulted mobile home ceiling?

[pvfjr]

So my mom's house is an older Fleetwood mobile home, 1400+ sqft, with an Earth Stove from the 70s. It's really not getting the job done anymore. The innards are warped, bricks missing, firebox cracking, etc. I'm thinking of installing a Blaze King like I did in my home, but there are some complications.

She lives way out in the sticks, gets a lot of snow, and needs a serious stove that will run many hours, for months in a row. Professional install is not being considered, for reasons of budget and location.

The existing stove runs 7" class A chimney all the way from the stove top to the chimney cap. Strange, but that's how it is. As such, there is no ceiling support box. I would simply install one in a normal house, but the "framing" of the ceiling and roof leave me wondering. The "trusses" consist of a 1x2 top and bottom, connected with thin plywood panels (3/16" maybe?). I'd never realized how lightweight the framing was before, but it's held 6 feet of snow in the past, and doesn't feel too bad when you're walking around up there.
So is it kosher to install a ceiling support box between these lightweight trusses? Was that conventional back in the day? Or do all mobile home installations leave the weight of the chimney sitting on the stove? I'm also wondering if the chimney weight contributed to the stove top cracking after all these years. It couldn't have helped.

 

[BKVP]

That's going to be a short stack in a mobile home. I would suggest the following:
Princess Ultra (taller for older folks) it has side shields already installed and get blowers or rear shield (not both), use 6" black double wall to ceiling support box and then leave the 7" all fuel chimney. See if you can get another 2' onto the 7", but try it first then decide if it is needed.

 

[webby3650]

Does the home have plywood decking? Shingles? Or just metal?
You could do a roof support rather than a ceiling box if there's decking up there.

 

[pvfjr]

That's going to be a short stack in a mobile home. I would suggest the following:
Princess Ultra (taller for older folks) it has side shields already installed and get blowers or rear shield (not both), use 6" black double wall to ceiling support box and then leave the 7" all fuel chimney. See if you can get another 2' onto the 7", but try it first then decide if it is needed.

OK, so reviewing the pictures more closely, I think it probably has 3 sections of 7"x3' class A, so the current stack is only 9'. That is definitely short. I like the idea of raising the class A up to the ceiling and supporting it there. That should net me another 6' of stack height. 15' would be a lot better than 12', and I'd only have to buy the stove pipe, and not any chimney, correct? I'd probably try to use one of those DSP telescopic double-wall stove pipes; that way she'd have the option of cleaning it without getting on a ladder.

So if I ran 6' of 6" double-wall stove pipe along with 9' of 7" class A along with the obligatory mobile-home OAK, do you think the draft would be sufficient for an Ashford 30.1? Where could I get a chimney adapter that would go from the 7" chimney to the 6" DSP?

Does the home have plywood decking? Shingles? Or just metal?
You could do a roof support rather than a ceiling box if there's decking up there.

There are typical asphalt shingles on top of plywood decking. The plywood looks thin in the pictures of the "trusses" above. Maybe 3/8"?

A roof support box, huh? Got a link? I don't think I've seen one of those...

 

[webby3650]

OK, so reviewing the pictures more closely, I think it probably has 3 sections of 7"x3' class A, so the current stack is only 9'. That is definitely short. I like the idea of raising the class A up to the ceiling and supporting it there. That should net me another 6' of stack height. 15' would be a lot better than 12', and I'd only have to buy the stove pipe, and not any chimney, correct? I'd probably try to use one of those DSP telescopic double-wall stove pipes; that way she'd have the option of cleaning it without getting on a ladder.

So if I ran 6' of 6" double-wall stove pipe along with 9' of 7" class A along with the obligatory mobile-home OAK, do you think the draft would be sufficient for an Ashford 30.1? Where could I get a chimney adapter that would go from the 7" chimney to the 6" DSP?



There are typical asphalt shingles on top of plywood decking. The plywood looks thin in the pictures of the "trusses" above. Maybe 3/8"?

A roof support box, huh? Got a link? I don't think I've seen one of those...

(broken link removed to http://www.woodlanddirect.com/6-inch-DuraTech-Roof-Support?gclid=EAIaIQobChMImM7pmp2P1gIVwrbACh0-mQVxEAQYBiABEgIrI_D_BwE)

 

[webby3650]

Inside all you'd need is a trim ring. You would need to pull the flashing up to install it though. An alternative is to hang the ceiling support from the roof deck. That's what we would do with an old mob like that. The trusses are just too small to really even drive a screw into.

 

[pvfjr]

(broken link removed to http://www.woodlanddirect.com/6-inch-DuraTech-Roof-Support?gclid=EAIaIQobChMImM7pmp2P1gIVwrbACh0-mQVxEAQYBiABEgIrI_D_BwE)

That's a neat idea, I'd need to find a bigger one for the 9" outer diameter of this 7" chimney. It looked like that one only fit 6". Oddly enough, it says 6" & 8", but I'm not seeing enough adjustability there to make up for a 2" difference in diameter. Are they referring to the ID & OD?

There's this one:
https://www.northlineexpress.com/7-duratech-roof-support-7dt-rs-7142.html
The drawing says the clamp diameter is 9", but it's called the 5" & 7" roof support. How would you use that with a 5" chimney? Their nomenclature makes no sense. I'd hate to have them ship me the wrong stuff.

Inside all you'd need is a trim ring. You would need to pull the flashing up to install it though. An alternative is to hang the ceiling support from the roof deck. That's what we would do with an old mob like that. The trusses are just too small to really even drive a screw into.

That's a good idea. I see some drawings of installations in the DuraTech manuals that show cutting the square ceiling support boxes at the corners and folding them out onto the deck to screw down. I suppose if I got a nice, tall, cathedral style mount, I'd be able to pass from the deck through the entire attic space with it and make it down past the ceiling. I would definitely need to fold it over the top edge too, though. I'm not sure why they didn't in the figure.

 

[webby3650]

I just referenced a support. 7" is available. The size listed is the ID.
You will need to find a support box that is the same brand as your pipe. Have you found any branding on the pipe? If it's obsolete you might be at a dead end.

 

[pvfjr]

I just referenced a support. 7" is available. The size listed is the ID.
You will need to find a support box that is the same brand as your pipe. Have you found any branding on the pipe? If it's obsolete you might be at a dead end.

I haven't found any branding, and it may be too late for that. She lives a long ways away, and the plan is to gather all the necessary parts so I can drive over there an do the install in a weekend. There are no hardware stores in the area either, so this will require careful planning.

I did find a universal bracket from Selkirk that screws to the chimney instead of clamping. It seem s like a viable option for me.
https://www.amazon.com/dp/B000DZHCVM/?tag=hearthamazon-20

 

[webby3650]

Although mixing brands isn't "approved".. roof supports are going to be pretty universal. Ceiling boxes will be very propitiatory though.

 

[pvfjr]

Although mixing brands isn't "approved".. roof supports are going to be pretty universal. Ceiling boxes will be very propitiatory though.

That makes sense. I think the universal screw-on roof support may be the best option then. Like you said, all I'd need is a trim ring on the inside, and I've already got one that's made to fit the existing 7" chimney pipe. It ought to do the trick.

 

[pvfjr]

Here's what I'm looking at so far price-wise. I've been unable to find an adapter that goes straight from 7" Class A to 6" DSP, so it looks like it'll take two separate pieces totaling $107 to make that connection. Does anyone know of a better option?

 

[webby3650]

The chimney adaptor will be brand specific. You will need to know the brand in order to buy an adaptor. If you have an adaptor to 7" on there, your best bet would be to get a double wall stove pipe 6" to 7" increaser.