How much does a chimney weigh?

20x20 inches, 25 feet tall. Originally 8" liner with red brick. Lined with 6" stainless set in place with a mortar of vermiculite.
And then- once I know how much it weighs- if I was to brace it with a support set at a 25degree angle, how strong a support do I need? Steel or wood?
Really long story- shortened; It has sat on a 8 foot high pillar of clay about 3x3 in my basement for 20 years. I want to remove the clay one side at a time and pour a 4x4 footing and a 2foot column. The 'temporary' bracing that was put in when the job was done will have to be removed to dig the footing.
To dig the first 1/2 I won't need to disturb 2 sides of the base- and I know it is tied to a slab that will be undisturbed. The support will be an extra safety- hopefully not needed.
thanks- Jim
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If you remove half the clay what is to stop it from falling straight down as you try to place the support. My chimney is like that and decided the dirt stays on a basement renovation, I dought you could do it without at least major damage as it could shift downward. Is that a 4" x4" footing, thats not enough. If you removed brick through it and got a big steel beam on jacks on big footers it might work. It sounds risky anyway you do it.
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-snip-
Brace first, dig second. I *think* that 1/2 the clay will hold it--- but I want to provide a brace that will take the whole load in the case of major catastrophe.

The footing that will eventually be under the new concrete column will be 4 feet square and 12" thick reinforced concrete. It will be poured in two pours and tied together with re-rod.

I don't doubt the risk. As long as I can keep it off my head, the house is repairable. But I'm pretty cautious- that's why I'm trying to get a real-world feel for how big the bracing has to be to do any good.
Jim
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Jim Elbrecht wrote:

Brick/mortar -- 120-150 lb/cu-ft SS -- 490
Need more dimension, geometry to figure out the actual (for instance, was the first liner removed or is the liner inside it), but you know that. Estimate volume, then weight is straightforward.
This would be good place for an engineer's help imo...
--
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Jim Elbrecht wrote:

This sounds like a job for a foundation repair professional.
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Pretty scary IMO. We had that situation in our palace and since the chimney was nothing sacred, it was simply removed brick by brick from the top and replaced by a nice tidy Metalbestos assembly. Part of the chimney,in addition, was a house support, so that was left intact under the first floor.and in the basement. Eventually it was also removed, a big footing and lally column installed. Holding up the house for the final removal was no big, deal, just a couple of post jacks, 6 x 6 shoring, some steel plates from the scrap yard and a 20 ton el cheapo hydraulic jack did the job. Using a level on the floor joists was a fringe benefit as some of the upstairs doors then decided to fit properly. Old houses are such fun.
Joe
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Jim Elbrecht wrote:

Common red brick weighs 120lbs/cu ft. You've got 20"(1.7 ft) x 20" x 25' 1.7x1.7x25 = 71 cu ft of chimney. That, times 120, is about 8500 lbs.
'Course that's for a stack of red bricks. Given that the stack's hollow, the total might be a bit less.
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remove chimney starting at roof, replace furnace and hot water tank with direct vent unit, gain some interior floor space and remove a roof maintence item
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-snip-

Thanks- I figured someone would have the numbers in their head-- I'm feeling a lot better about my lolly column rated at 18000pounds. Jim
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Jim Elbrecht wrote:

Actually, I didn't. I Googled "Density+red+brick" and got:
http://www.simetric.co.uk/si_materials.htm
among others.
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In addition to the other suggestions, if you decide to do this yourself I would suggest that instead of removing half of the support you remove only one fourth at a time. It seems to me that removing half of the support would be fairly likely to cause failure of the structure and/or the support itself.
Don Young
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Does your insurance cover you as a HO screw up or does it need a contract of a real hack-pro, You might be suprised after it causes 50,000.00 in damage as to who pays. ITS YOU
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How much wood could a woodchuck chuck if a woodchuck could chuck wood?
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