Clearance not obtainable/contradicting

[Maj92az]

My duravent ceiling support obviously is framed in. Its 10" wide. The 6" chimney is about 8" diameter. Leaves 1 inch from all 4 framed sides.

Now within the support box is the duravent class A chimney that suddenly calls for 2". The manual reads other than the framing, must maintain 2". Ceiling rafters are on the same plane as roof rafters. If I'm 1" away down at the ceiling. I'm 1" away at the rafter and the roof decking. Obviously I can cut the decking to meet 2" except when it meets the rafter on one side.

I left a voicemail for duravent. The verbiage isnt clear but by design of nearly ever roof, plus how they stress to keep it level and plumb .. you'd always be on the same plane from the ceiling support joist. A way to fix it which is clearly not done in the manual would be to center the chimney inside the rafters- rather than using a rafter as 1 side. Then again you are still less than the two- but says 2" other than framed (lower??) Support.

 

[ADDvanced]

Does anyone know when this 2" clearance started? Because I'm guessing MOST buildings in the united states were built prior to this standard.

 

[Maj92az]

Does anyone know when this 2" clearance started? Because I'm guessing MOST buildings in the united states were built prior to this standard.

It's the other way around.. it's the modern equipment (chimney pipe, class A ect) and its location that the installer chooses. Every component has it's own- not necessarily a building practice.

 

[bholler]

Does anyone know when this 2" clearance started? Because I'm guessing MOST buildings in the united states were built prior to this standard.

This is for a prefab chimney their clearances are set by the manufacturer by testing the chimney system and is certified by testing to ul standards. The clearances for masonry chimneys have been required since the late 70s or early 80s. And yes chimneys built prior to that are technically grandfathered in with regard to codes as long as a different appliance hasn't been installed since or a liner installed etc. When you do that you are responsible to bring it up to code.

And regardless of code compliance those clearance requirements were put in place because it was forms that there is a significant fire risk without them.

And yes the majority of chimneys we inspect that were built after those requirements are lacking required clearances as well.

 

[bholler]

My duravent ceiling support obviously is framed in. Its 10" wide. The 6" chimney is about 8" diameter. Leaves 1 inch from all 4 framed sides.

Now within the support box is the duravent class A chimney that suddenly calls for 2". The manual reads other than the framing, must maintain 2". Ceiling rafters are on the same plane as roof rafters. If I'm 1" away down at the ceiling. I'm 1" away at the rafter and the roof decking. Obviously I can cut the decking to meet 2" except when it meets the rafter on one side.

I left a voicemail for duravent. The verbiage isnt clear but by design of nearly ever roof, plus how they stress to keep it level and plumb .. you'd always be on the same plane from the ceiling support joist. A way to fix it which is clearly not done in the manual would be to center the chimney inside the rafters- rather than using a rafter as 1 side. Then again you are still less than the two- but says 2" other than framed (lower??) Support.

I will look up their instructions later but some chimneys allow reduced clearances while the chimney is inside the support box or radiation sheild. I don't use duravent so I don't know their requirements off the top of my head. I will try to figure it out.

Exactly what model chimney are you using? Duravent has a couple different lines

 

[Highbeam]

My duravent ceiling support obviously is framed in. Its 10" wide. The 6" chimney is about 8" diameter. Leaves 1 inch from all 4 framed sides.

Now within the support box is the duravent class A chimney that suddenly calls for 2". The manual reads other than the framing, must maintain 2". Ceiling rafters are on the same plane as roof rafters. If I'm 1" away down at the ceiling. I'm 1" away at the rafter and the roof decking. Obviously I can cut the decking to meet 2" except when it meets the rafter on one side.

I left a voicemail for duravent. The verbiage isnt clear but by design of nearly ever roof, plus how they stress to keep it level and plumb .. you'd always be on the same plane from the ceiling support joist. A way to fix it which is clearly not done in the manual would be to center the chimney inside the rafters- rather than using a rafter as 1 side. Then again you are still less than the two- but says 2" other than framed (lower??) Support.

I just measured my duravent ceiling support box and it is 12" wide. This provides the 2" clearance on all sides of class A pipe which has been the standard for at least decades.

 

[bholler]

I just measured my duravent ceiling support box and it is 12" wide. This provides the 2" clearance on all sides of class A pipe which has been the standard for at least decades.

I know Excell pipe reduces clearances inside their shields and boxes. But I haven't had a chance to check duravent yet. And without knowing exactly which chimney it is it would be difficult

 

[Highbeam]

Was your ceiling support box intended to support a 4" pellet vent? If it's really 10" wide then you'll need to scab on a 2x to the side of your bottom truss chord to space it away so that you don't run into clearance issues at the top chord.

Not all houses use trusses. Mine uses rafters that are not on plane with the ceiling joists.

 

[begreen]

This is the square DuraTech ceiling support box.

 

[Maj92az]

Thanks guys. Yes one of you are right. Once again duravent tech called me back.. so yes the "reduced clearance ceiling support box" does reduce but I could not find the verbiage on how much.. neither could tech support. I wasnt buying it.. the next idea was cut and dry and as one of you suggested.. I attached another 2x4 against my ceiling truss and extended my box another 2" (1.75" really). Between that and being "plumb" my class A will stay away with that edge.

I screwed it in and while I'm a bit away still with some demo and hearth work... I lifted her into place. I hope being off center (like planned) isnt big deal. I'm at 7" on right and 13" on left (5" minimum for a corner).

Does she look alright? Otherwise I need to deal with an offset but wasnt trying to do that or buy more dang pipe (the picture is looking straight on at a 45.)

 

[begreen]

Put some fireplace tools on the left side or an ammo can or copper wash boiler for kindling to balance out the look and make it look intentional.

What's happening on the left side past the hearth? It looks like a fireplace demo in progress.

 

[Maj92az]

Yes, as stated I am doing some demo. It's an old not repairable prefab stick built ZC insert from the 80s. I will remove it up to the same level so I can replace the T&G panels.

The room will open up without that junk there and then stove, even if off centered from the corner will look good. I hope!!