Section 321.29. Masonry fireplaces.

  Masonry fireplaces shall be constructed of masonry, stone or concrete. Masonry fireplaces shall be supported on foundations of concrete or masonry. Structural walls shall be at least 8 inches thick. Masonry fireplaces shall conform to the following requirements:

(1)   Flue size. The fireplace flue size shall be based on the type of flue and the fireplace opening indicated in Table 321.29. - See PDF for table

(2)   Termination of chimney. Masonry fireplace chimneys shall extend at least 3 feet above the highest point where the chimney passes through the roof and at least 2 feet higher than any portion of the dwelling within 10 feet of the chimney.

(3)   Firebox materials. The firebox shall be of the preformed metal type, at least ¼ -inch thick, or listed by a nationally recognized laboratory; or shall be lined with firebrick, at least 2 inches thick and laid in thin joints of refractory cement. The back and sidewalls of the firebox, including the lining, shall be at least 8 inches nominally thick masonry, at least 4 inches of which shall be solid.

(4)   Lintel. Masonry over the fireplace opening shall be supported by a lintel of steel or masonry.

(5)   Ducts. Warm-air circulating ducts shall be constructed of masonry or metal.

(5m)   Return air grilles. Return air grilles shall not be located in bathrooms, kitchens, garages, utility spaces or in a confined space defined under s. SPS 323.06 in which a draft diverter or draft regulator is located.

(6)   Hearth extension.

(a) Masonry fireplaces shall have a hearth extension made of noncombustible material.

(b) The structural support for the hearth and hearth extension shall be a minimum of 4 inches of reinforced concrete.

(c) There shall be no structural framing material within 1 inch of the hearth or hearth extension in any direction. Any wooden forms or supports used during construction shall be removed.

(d) The minimum dimensions of the hearth extension shall be in accordance with Table 321.29-1. - See PDF for table

(7)   Dampers. Dampers shall be made of cast iron or at least No. 12 gauge sheet metal. The area of the damper opening shall be at least 90% of the required flue area when in the open position.

(8)   Hoods. Metal hoods, used in lieu of a masonry smoke chamber, shall be constructed of at least No. 19 gauge corrosion-resistant metal with all seams and connections of smokeproof construction. The hood shall be sloped at an angle of 45 ° or less from the vertical and shall extend horizontally at least 6 inches beyond the firebox limits. Metal hoods shall be kept a minimum of 18 inches from the combustible materials unless approved for reduced clearances.

(9)   Flue liners.

(a) Flue liners shall be installed in accordance with s. SPS 321.30 (7) and this section.

(b) Flue liners shall start at the top of the fireplace throat and extend to a point at least 4 inches above the top of the chimney cap.

(c) Firebrick may be used in the throat of the fireplace as an inlet to the flue liner.

(10)   Cleanout openings. Fireplaces with ash dumps shall be provided with cleanout openings at the base. Doors and frames of the opening shall be made of ferrous materials.

(11)   Mantel shelves and combustible trim. Woodwork or other combustible materials shall not be placed within 6 inches of the fireplace opening. Combustible materials located within 12 inches of the fireplace opening shall not project perpendicularly more than 1 / 8 -inch for each inch distance from the opening.

(12)   Framing around fireplaces. Combustible materials located near fireplaces shall be installed in accordance with s. SPS 321.30 (9) .

(13)   Corbeling. Unless designed through structural analysis, masonry chimneys shall not be corbeled from a wall more than 6 inches nor shall a masonry chimney be corbeled from a wall less than 12 inches in nominal thickness unless it projects equally on each side of the wall. The corbeling shall not exceed one-inch projection for each brick course.

Cr. Register, November, 1979, No. 287 , eff. 6-1-80; am. Register, February, 1985, No. 350 , eff. 3-1-85; am. (6) and Table 21.29-1, Register, January, 1989, No. 397 , eff. 2-1-89; am. (intro.) and (12), cr. (5m), r. and recr. (6), Register, March, 1992, No. 435 , eff. 4-1-92; r. (12) and renum. (13) and (14) to be (12) and (13), Register, January, 1999, No. 517 , eff. 2-1-99; r. and recr. (6) and (9), Register, March, 2001, No. 543 , eff. 4-1-01; correction in (1), (5m), (6) (d), (9) (a), (12) made under s. 13.92 (4) (b) 7. , Stats., Register December 2011 No. 672 .

Note

The department will accept dampers and hoods listed by nationally recognized laboratories. Microsoft Windows NT 6.1.7601 Service Pack 1