Any know chimneys?

B

Bob W

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Dec 31, 2000
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The brick chimney on our house is about 25' tall, perhaps 10 feet shorter than the highest peak of the roof. Rising from the brick chimney was about 8' of round stovepipe.

Originally the chimney was built as a smokestack for a coal-burning boiler. Sometime in the 1980s the boiler was updated to natural gas, and the chimney still serves as an exhaust to the gas boiler.

A couple of weeks ago a strong windstorm blew off the stovepipe section, which was apparantly weakened by rust at the base.

None of the local contractors return phone calls for small jobs, so I'm figuring maybe I can do this myself. It's not too hard to access, being there's a flat roof over an addition on that side of the house - means I only have to climb about 15' on a ladder.

So here's my question: Do I need to replace the stovepipe section, or can I simply use a vented chimney cap? Should I be worried about downdrafts, since the brickwork is lower than the roof peak? I'm not worried about gas buildup in the basement, since there's a large pipe that vents the basement directly outside, but could a downdraft potentially extinguish the boiler pilot?

Also, not having the stovepipe extension would allow me to eliminate three guy-wires.

From looking in the basement it appears that there is no liner flue, so I need a metal cap that covers the entire chimney top. Is that going to be a problem?

Relevent picture to be posted momentarily...

-Bob
 
DCAM0002.jpg


I want to make sure the end result is not just functional but 'legal' also, but I'm having trouble finding relevent 'rules' online anywhere.

-Bob
 
You should use stainless steel pipe. You have to check the building codes for limits on height etc perhaps a furnace dealer could help you there.
 
You should use stainless steel pipe.
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I sort of like the rust - a bright shiny pipe creates an eyesore from very far distances. But you're right, I don't want to be up there replacing the darn thing every 80 years... I'll be 118 years old the next time it rusts and falls off, that's too old to be monkeying around on ladders.

Just being a smart-ass. ;)

I wonder if they even make pipes that aren't stainless or galvanized any more? Maybe I can paint the pipe before I put it up... Copper would be great, but I bet it's too expensive. Cast iron, like the sewer exhausts, would last forever, but that's too heavy to be balanced on top of a brick chimney. :)

-Bob
 
Looks to me like the metal stovepipe was an addition to a standard brick chimney. It was probably added to stop down draft and smoking because of the close proximity to the roof apex. I would remove it and see what is underneath? You could just add a clay pot with a vented top or an H-cowl if you are worried about the pilot light being blown out. If it does get blown out, it cuts off the gas, but would be a pain to keep re-lighting it. For my money, it is unlikely that this will happen.
 
I agree with Andrew. I believe the extra section was probably added to improve furnace draft on the coal boiler and/or meet the new codes. According to code, the chimney must extend at least 2 feet above any portion of any structure within 10 feet (measured horizontally) AND must extend at least 3 feet above the highest point of its roof penetration.

Check out this link for a drawing that explains this: http://www.usinspect.com/car/0104TechJargChimneyHeight.asp
And here: http://www.usinspect.com/Chimney/ChimneyHeight.asp

Bring a tape measure up with you and see what you get.

Before he would install a new furnace and attach it to that brick chimney, a contractor around here would make you install a stainless steel liner, extend the chimney up to the required height, and cap it. I went through that myself about four years ago. If you change insurance companies, they may require it upon their inspection as well.

Good Luck,
Scott
 
Thanks for the picture. That was a great explanation.

The 3' part is 'iffy' without the extention. Definitely clears on the front, but maybe not on the back.
The 2'/10' part is probably not clear without the extension. But I bet only one pipe section is necessary.
That'll be something to check out with a tape measure.

Too bad contractors don't return phone calls...

Had a similar problem with a code a few years ago - the power line wasn't six feet over the carport. A mast tall enough to create the clearance would have been ridiculous, and a hazard.

Thanks and best wishes,
-Bob
 
Hi, just a thought on safety.

As the building is old, the mortar between the bricks is probably lime. It appears from your photo to be somewhat eroded and it is important to remember that lime mortar does not act like glue in the way that cement does.

Be very careful before you lean a ladder against that stack, in other words!

Andy
 
Thanks for the advice. Some of the chimney bricks need re-pointing, as you can see in the picture. But the structure is secure overall. Still, I'd hate to have one of those bricks loosen and fall on the roof below. I should definitely get that done while I have the ladder up there.

That's an easy job, and I'm pretty good at minor masonry repairs. I wouldn't even consider paying some mope $20/hr to repoint bricks. :)

-Bob
 
Andrew Taylor said:
Looks to me like the metal stovepipe was an addition to a standard brick chimney. It was probably added to stop down draft and smoking because of the close proximity to the roof apex. I would remove it and see what is underneath? You could just add a clay pot with a vented top or an H-cowl if you are worried about the pilot light being blown out. If it does get blown out, it cuts off the gas, but would be a pain to keep re-lighting it. For my money, it is unlikely that this will happen.
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Check your building codes - where I live, the top of the chimney has to be some number of inches/feet above the highest point on the roof.

For wood burning fireplaces, it's to keep your house from burning down in wind - if the top of the chimney is below the top of the roof, cinders can be blown sideways and hit the roof, igniting it.

Even if you don't burn wood, the building codes may still require the height.
 
j22knife said:
Check your building codes - where I live, the top of the chimney has to be some number of inches/feet above the highest point on the roof.

For wood burning fireplaces, it's to keep your house from burning down in wind - if the top of the chimney is below the top of the roof, cinders can be blown sideways and hit the roof, igniting it.

Even if you don't burn wood, the building codes may still require the height.
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My point is that the chimney was originally within code and the metal was an addition at a later date. You don't have to alter existing situations when the building codes are updated unless you submit planning changes.
 
More and better pictures please.
Get that thing off your roof, LOL.

You can buy black thick walled stove pipe still,though I'm not sure it was intended for constant exposure to the weather. I'd shoot for copper just for effect. Materials are cheap good labor is expensive.
 
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