I will post pics of my install once complete, but in the meantime I was wondering if someone could direct me on the best and safest way to go through my interior ceiling (10/12) to roof (12/12) with class A ICC excel chimney. I have a two story cabin I am building and will be running class A up from the 2nd story floor. It will not enclosed by a chase(not code), but I will build a small fence around it at floor level to protect it from bumps. There is no code up here. My attic space is about three feet deep. My options are:
1. Build chase/attic radiation shield out of plywood in the attic with required 2" clearances from class A. I would close off the ceiling with a pitch ring.
2. Install a cathedral attic radiation shield instead of the chase (it is a sheet metal enclosure). ICC Excel sales a cathedral attic radiation shield that I would buy.
3. Do a combination of both (this would create a 1" dead air space outside of the radiation shield and would likely be overkill, but still pretty easy and to me the safest way.
The attic is vented with soffit and ridge vents. I am unsure whether to terminate the radiation shield a few inches above the insulation and use a storm collar, or continue it up to the underside of the roof flashing. My thoughts are if I terminate it just above the insulation, the cold attic air (approximately 1' of air space) will keep the pipe cooler and possibly safer while at the same time allowing better ventilation by drawing up cold air from the soffits. On the other hand, if I continue it up to the outside flashing/roof then it will keep the chimney hotter and help draft (I just don't want it to superheat the area near the roof and create a potential fire hazard). I am also worried that if I continue it up to the roof, any moisture drawn out of the house will be pushed to the ceiling with less air space to ventilate out the ridge vent. I know I am overthinking this and no matter what I do will be fine so long as the 2" to combustibles is met, but what is best? The roof flashing and one section of chimney is already in (secured with universal roof brace) and the chimney exit is near the peak of the roof about 1 foot down.
1. Build chase/attic radiation shield out of plywood in the attic with required 2" clearances from class A. I would close off the ceiling with a pitch ring.
2. Install a cathedral attic radiation shield instead of the chase (it is a sheet metal enclosure). ICC Excel sales a cathedral attic radiation shield that I would buy.
3. Do a combination of both (this would create a 1" dead air space outside of the radiation shield and would likely be overkill, but still pretty easy and to me the safest way.
The attic is vented with soffit and ridge vents. I am unsure whether to terminate the radiation shield a few inches above the insulation and use a storm collar, or continue it up to the underside of the roof flashing. My thoughts are if I terminate it just above the insulation, the cold attic air (approximately 1' of air space) will keep the pipe cooler and possibly safer while at the same time allowing better ventilation by drawing up cold air from the soffits. On the other hand, if I continue it up to the outside flashing/roof then it will keep the chimney hotter and help draft (I just don't want it to superheat the area near the roof and create a potential fire hazard). I am also worried that if I continue it up to the roof, any moisture drawn out of the house will be pushed to the ceiling with less air space to ventilate out the ridge vent. I know I am overthinking this and no matter what I do will be fine so long as the 2" to combustibles is met, but what is best? The roof flashing and one section of chimney is already in (secured with universal roof brace) and the chimney exit is near the peak of the roof about 1 foot down.
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