Thread: Hearth extension code?

I was wondering what the hearth extension code is for a raised factory built fireplace. The bottom of the firebox is 2 feet from the combustible flooring. Thanks.

NFPA 211

11.3.2 The minimum thickness of hearth extension shall be
2 in. (51 mm).
11.3.3 Where the fireplace opening is less than 6 ft2 (0.56 m2),
the hearth extension shall extend as follows:
(1) At least 16 in. (406 mm) in front of the facing material
(2) At least 8 in. (203 mm) beyond each side of the fireplace
opening (See Figure 11.3.3.)
11.3.4 Where the fireplace opening is 6 ft2 (0.56 m2) or
larger, the hearth extension shall extend as follows:
(1) At least 20 in. (508 mm) in front of the facing material
(2) At least 12 in. (305 mm) beyond each side of the fireplace
opening (See Figure 11.3.3.)
11.3.5 Where a fireplace is elevated above or overhangs a
floor, the hearth extension also shall extend over the area under
the fireplace.

Thanks Marc. You're the man.

Originally Posted by Robert W

Thanks Marc. You're the man.

Just looking out for my boys in CA

Originally Posted by Marc M

NFPA 211

NFPA 211 is good stuff, however that is a factory fireplace and the instructions will list the hearth requirements for that unit including the ember strip 1/2 under the fireplace, 1/2 under the hearth.

In my area of CA that unit would also need glass doors.

Originally Posted by Marc M

NFPA 211

11.3.2 The minimum thickness of hearth extension shall be
2 in. (51 mm).
11.3.3 Where the fireplace opening is less than 6 ft2 (0.56 m2),
the hearth extension shall extend as follows:
(1) At least 16 in. (406 mm) in front of the facing material
(2) At least 8 in. (203 mm) beyond each side of the fireplace
opening (See Figure 11.3.3.)
11.3.4 Where the fireplace opening is 6 ft2 (0.56 m2) or
larger, the hearth extension shall extend as follows:
(1) At least 20 in. (508 mm) in front of the facing material
(2) At least 12 in. (305 mm) beyond each side of the fireplace
opening (See Figure 11.3.3.)
11.3.5 Where a fireplace is elevated above or overhangs a
floor, the hearth extension also shall extend over the area under
the fireplace.

Chapter 11.1 of NFPA 211 applies to Factory-built fireplaces: 11.1.2 " Hearth extensions shall be provided in accordance with the manufacturer's instructions or shall be of masonry or on-combustible construction in accordance with Section 11.3 (see above). [manufacturer's instructions always take precedence over the code.]

Originally Posted by Mark Sokalski

[manufacturer's instructions always take precedence over the code.]

Not if the code is more restrictive.

The codes reference the code AND the manufacturer's installation instructions, which means the most restrictive of the two apply.

Mamy (most) codes state "the most restrictive" shall apply, and "this code and the manufacturer's installation instructions" and even something similar to 'unless the manufacturer's installation instructions violate this code, then the code shall apply'.

Haven't done the inspection yet, that's tomorrow so I can't post my own pic. However, looking at the OPs pic and from what I can see with listing pics, the fireplace looks very similar, I.e factory built and elevated 18" or so. The differences being that with tomorrow's challenge, the fireplace has glass doors and the floor directly below them is tile, as is the whole of the ground floor. The hearth itself is not raised but also of a non-combustible material - floor tile but set on a diagonal to differentiate from the rest of the floor. I'm of the opinion that it still does not negate the requirement for a raised hearth.

This is a 2006 tract home, without modification (I'm told) and clearly passed AHJ final occupancy inspection and approval. Thoughts?

Originally Posted by Ian Page

Haven't done the inspection yet, that's tomorrow so I can't post my own pic. However, looking at the OPs pic and from what I can see with listing pics, the fireplace looks very similar, I.e factory built and elevated 18" or so. The differences being that with tomorrow's challenge, the fireplace has glass doors and the floor directly below them is tile, as is the whole of the ground floor. The hearth itself is not raised but also of a non-combustible material - floor tile but set on a diagonal to differentiate from the rest of the floor. I'm of the opinion that it still does not negate the requirement for a raised hearth.

This is a 2006 tract home, without modification (I'm told) and clearly passed AHJ final occupancy inspection and approval. Thoughts?

If it has a glass panel covering the front of the fireplace with direct vent gas logs, the hearth is a non-issue. The NFPA 211 was primarily written to cover wood burning fireplaces, where logs, embers, etc could fall out of the opening….. Sometimes common sense needs to win…

Having a hard time posting a pic...but anyway, the fire box and hearth is s I first saw. A Superior fire box, capable of handling logs and other flamables with bi-fold glass doors (not fixed as they would be for a vented gas log set) and a mesh spark screen. Hearth is level with surrounding tile floor and not raised. Any extensions, as required, is thereby moot. Firebox is 16" above tile.
Definately a hazard to young'uns, walking into the fire when lighted.