Chimney Footer

Old 10-06-08, 01:21 PM
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Chimney Footer

I am building an interior masonry chimney beginning on my basement floor slab. It is a 4" concrete slab, no reinforcement. I will building up through two floors for a total height of about 30 feet. The blocks and clay line will be large to handle 2 or 3 stoves. What footer thickness, width and reinforcing do you recommend?
Old 10-06-08, 03:53 PM
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Chimney Footer

A chimney that wbig and tall should not be built on a 4" unreinforced basement slab. You have no idea what the sol is under the slab and what kind of concrete was used and there is no structural reinforcement.

You should cut (saw) an area for he size of the planned chimney footing. The thickness and soil capacity should be adequate to support the load independaent from the existing structure.

The information you supplied is not adequate to give a recomenedation on an exact size. One big variable is the unreinforced slab and the support under the slab. If you have too much load and the concrete is not strong enough and the uncompacted soil has settled (as it does under a simple basement slab), you will get uncontrolled floor cracks and sometimes settlement.

Find someone (like and engineer) to give you a design that he will stand behind.

Nothing is worse than a 2+ story chimney the settles unevenly and tilts, causing a problem with the rest of the house. If you do nothing, it could work, but who knows.

Old 10-06-08, 07:31 PM
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It will require an engineer's stamp in most places anyway.

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