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Adding A New Chimney On An Existing House

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Old 03-19-2011, 02:59 PM   #1
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Adding A New Chimney On An Existing House

Hi, new to the forum here so take it easy on me.

I bought a house a year ago. The house was built in 2001 with 2x6 construction, 1/2" sheathing and vinyl siding. The house does not have a chimney. The contractor skimped out and installed a powervent for the boiler and the previous owners rarely serviced the boiler and the side of the house was black!

My intention is to install a 3 flue brick chimney on the side of the house and core drill through the foundation, tapping into the new flue for the boiler. Additionally, I intend to install a wood boiler later down the line as well as a wood stove on the first floor (hence 3 flues). I had a mason quote me $7500 for a three flue chimney. That quote was for a 42' chimney, I would do the footing, remove and re-install the siding & fascia. He would tie in the roofing. I asked him about proper airspace and he said no airspace is required on the outside of a building using solid brick or block. I told him I would think about it but that answer made me to never call him back.

With CMU block & brick experience, I may decide to install the chimney myself. However, based off of research, 1" of airspace is needed between combustibles, in this case, the sheathing. My question is, is there a material that can be placed between the chimney and the sheathing at the ends of the chimney to avoid having a 1" gap? Thanks.
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Old 03-19-2011, 04:10 PM   #2
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Re: Adding A New Chimney On An Existing House

First of all this site is for professionals. You will get better assistance at the DIY chatroom.

Second of all, I'd be wary of a mason who would do a 42' tall, 3 flue chase and chimney for $7500... unless you live in China somewhere.


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Old 03-19-2011, 04:16 PM   #3
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Re: Adding A New Chimney On An Existing House

Originally Posted by 6stringmason View Post

Second of all, I'd be wary of a mason who would do a 42' tall, 3 flue chase and chimney for $7500... unless you live in China somewhere.
or unless he shows up naked and has an okie drawl.
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Last edited by lukachuki; 03-19-2011 at 06:19 PM.
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Old 03-19-2011, 07:34 PM   #4
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Re: Adding A New Chimney On An Existing House

I was thinkin maybe it was a typo and it was a 24' chimney. Even then I thought $7500 for a three flue was cheap. Even for the okie who was plannin on waitin for the price of those used boxers to get to a dime.
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Old 03-19-2011, 08:17 PM   #5
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Re: Adding A New Chimney On An Existing House

I am confused.

Why a chimney when it appears youonly maY HAVE A PROBLEM, with the current system.

Most HVAC systems today do not use a chimney.
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Old 03-20-2011, 07:57 AM   #6
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Re: Adding A New Chimney On An Existing House

Without getting too far into details, I want a 3 flue chimney for a wood burning stove, a wood burning boiler and for the oil boiler. I could have 3 class A's installed and make a chase but for asthetics, I prefer masonry. Besides, the direct vent is a dirty system, I've been told the blower goes every 5 years, and there's a strong smell of fumes in the upstair bedrooms (above the boiler vent) whenever the windows are open.

I don't know if I'm going to do it myself. But, I want it done correctly. I want to know the ruling, whether 1" airspace is required and what's the proper way to make that 1" gap watertight...
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Old 03-20-2011, 08:25 AM   #7
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Re: Adding A New Chimney On An Existing House

Desde, I don't know where you are located, but a couple things. When your mason said there wasn't an airspace needed, he may be right. In MA, where I work, and exterior chimney can be laid up right to the sheathing. I do not do that, and have never liked that....I will keep 2" generally until I get up to the rake (or cricket) and then corbel out to the sheathing at that point. Now, where the brick or stone meet on the sides, I will be fairly tight.....but in between, I'll keep 2". There are a couple of ways to make this area watertight.....I've posted some pics here before with the method I use, a lot of our rain comes with 50 mph winds, so we need to go the extra bit. You can just ask a good builder in your area for a common, effective treatment. So, you can go to the sheathing, you can leave don't need to add anything else.....You could, it's just not necessary....NEXT// That price is awfully low, although maybe your mason hijacked a truck, I don't know. Or he pays his help 6 bucks an hour.......Just check his work. Good luck!
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Old 03-20-2011, 11:14 AM   #8
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Re: Adding A New Chimney On An Existing House

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