I looked for about an hour but didn't find much on this topic. What I have is a 100 yr old house that has a 4 flue masonry (unlined) chimney which was knocked off below roofline when the roof was replaced. I've had two inspections, one with camera, and was assured that there are no issues with structural integrity (just typical of what you'd find in a reasonable chimney that's 100 yrs old). It's likely that the masonry above the roof was crumbling, so they took it down.
The mantle in this place is gigantic and well...majestic...maybe that's a little much, but I'd like to use it for something other than this. My heating costs (2400 ft2) are well into $600-700 in the coldest months even with a year's worth of time and well over $3500 of insulation, sealing openings, cracks, etc.
What I need to know is what exactly can I do at the top of the chimney to maintain a comfortable level of safety. I worry about the fact that the chimney itself is the chase. If a chimney fire started, the chimney would typically contain it (hopefully) and give you that margin of safety, but in my case the fire in the chase/flue would head into the attic, hit the top/transition plate and maybe contain it. Or, it could get too hot, possibly starting sheathing, etc on fire. Not really the effect I'm going after.
What would it take to do this transition safely and what in your opinion is the safer option? Should I think about rebuilding the masonry up above the roofline again, and just lining it the whole way? OR Could I do liner up to the lip of the chimney, use a transition plate and go class A double wall rigid the rest of the way? The chimney also comes through the attic ceiling with about 12" between the floor and chimney top, and about 12" from chimney top to nearest sheathing (I KNOW it's 24" from sheathing to attic floor, can't remember the chimney measurements, but they're 12"+/-1"). Oh, the flue I'm looking at is fairly strait, I've sent a 6" x 8' piece of aluminum flex duct with 1" wrap down the flue as a test fit. I fit one that was worse, I'm pretty sure this one will only take moderate cussing.
Of prime importance is safety...I'm not sure I'll even attempt anything unless I'm 99% sure it's safe (maybe both options are safe, then cost comes into play), I'd rather pay thousands of dollars feeding the gas furnace than endangering my life...also would like to protect the investment and the 1000+ hours I've put into it.
Also, any ballpark ideas of cost? I'd like to have an expert do it, if I can find one around here, but can do myself (I've done two complete, but straitforward) chimney linings. I got a quote from the only chimney sweep in the area that's bothered to call me back....$3200, but his plans were to run insulated flex liner out the sheathing with..and I quote: "two or three inches" clearance. If he went by code (which he apparently doesn't), I'd also have a piece of flex pipe about 5' long sticking out my roof (12/12 pitch). No thank you, I said. Aside from the fact that he's going to burn the place down, $3200 is steep for 30' of flex install.
Thanks in advance.
Chris.
PS - a third option that I'm going to explore is going rigid all the way down (although I'd need about 5' of flex at the bottom to center the connection). The flue doesn't bend, but there's a slight drift to one side, I might not be able to get it strait. What's the code on that? what if it was 5 degrees off? It would look funny above the roof, but if it's ok....
The mantle in this place is gigantic and well...majestic...maybe that's a little much, but I'd like to use it for something other than this. My heating costs (2400 ft2) are well into $600-700 in the coldest months even with a year's worth of time and well over $3500 of insulation, sealing openings, cracks, etc.
What I need to know is what exactly can I do at the top of the chimney to maintain a comfortable level of safety. I worry about the fact that the chimney itself is the chase. If a chimney fire started, the chimney would typically contain it (hopefully) and give you that margin of safety, but in my case the fire in the chase/flue would head into the attic, hit the top/transition plate and maybe contain it. Or, it could get too hot, possibly starting sheathing, etc on fire. Not really the effect I'm going after.
What would it take to do this transition safely and what in your opinion is the safer option? Should I think about rebuilding the masonry up above the roofline again, and just lining it the whole way? OR Could I do liner up to the lip of the chimney, use a transition plate and go class A double wall rigid the rest of the way? The chimney also comes through the attic ceiling with about 12" between the floor and chimney top, and about 12" from chimney top to nearest sheathing (I KNOW it's 24" from sheathing to attic floor, can't remember the chimney measurements, but they're 12"+/-1"). Oh, the flue I'm looking at is fairly strait, I've sent a 6" x 8' piece of aluminum flex duct with 1" wrap down the flue as a test fit. I fit one that was worse, I'm pretty sure this one will only take moderate cussing.
Of prime importance is safety...I'm not sure I'll even attempt anything unless I'm 99% sure it's safe (maybe both options are safe, then cost comes into play), I'd rather pay thousands of dollars feeding the gas furnace than endangering my life...also would like to protect the investment and the 1000+ hours I've put into it.
Also, any ballpark ideas of cost? I'd like to have an expert do it, if I can find one around here, but can do myself (I've done two complete, but straitforward) chimney linings. I got a quote from the only chimney sweep in the area that's bothered to call me back....$3200, but his plans were to run insulated flex liner out the sheathing with..and I quote: "two or three inches" clearance. If he went by code (which he apparently doesn't), I'd also have a piece of flex pipe about 5' long sticking out my roof (12/12 pitch). No thank you, I said. Aside from the fact that he's going to burn the place down, $3200 is steep for 30' of flex install.
Thanks in advance.
Chris.
PS - a third option that I'm going to explore is going rigid all the way down (although I'd need about 5' of flex at the bottom to center the connection). The flue doesn't bend, but there's a slight drift to one side, I might not be able to get it strait. What's the code on that? what if it was 5 degrees off? It would look funny above the roof, but if it's ok....
