Fireplace hearth extension cantilever

[FlipFlopLife]

A new construction woodburning fireplace will be built, fieldstone-clad, with a raised hearth, similar to the one in the photo.  The mason proposes to build the hearth extension simply laying atop the adjoining wood-framed floor structure, rather than cantilevering a reinforced concrete slab from the all-masonry fireplace structure.

Should the AHJ allow this?  The former AHJ official, in office for many years, was weak on code and inspection, and permitted many fireplaces built by this mason this way, while other masons were doing cantilevered slabs to support extensions.  The new AHJ official, who lists a small array of alphabet symbols after his name to cite his training and certification, may not catch this.

Should he?

[Jim Katen]

Of course it's wrong. 

1001.9 Hearth and hearth extension. Masonry fireplace hearths and hearth extension shall be constructed of concrete or masonry, supported by noncombustible materials, and reinforced to carry their own weight and all imposed loads. No combustible material shall remain against the underside of hearths and hearth extensions after construction. 

[HomeInspectionNewark]

No way, as pointed out before - combustible material on the underside of hearths are a no no.

 

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Sterling