Buckley Rumford Fireplaces
2013 IRC Code Change Proposal RB457

R1002.5, Chapter 44

Proponent: Timothy N. Seaton, B.S.C.E., Empire Masonry Heaters LLC (tseaton@timelyconstruction.com)

Revise as follows:

1002.5 Masonry heater clearance. Combustible materials shall not be placed within 36 inches (914 mm) or the distance of the allowed reduction method of from the outside surface of a masonry heater in accordance with NFPA 211, Section 8-7 (clearances for solid fuel-burning appliances) 12.6, Clearances from Solid Fuel-Burning Appliances, and the required space between the heater and combustible material shall be fully vented to permit the free flow of air around all heater surfaces.


      1. When the masonry heater is unlisted wall thickness is at least 8 inches (203 mm) thick of solid masonry and the wall thickness of the heat exchange channels is at least 5 inches (127 mm) thick of solid masonry, combustible materials shall not be placed within 4 inches (102 mm) of the outside surface of a masonry heater. A clearance of at least 8 inches (203 mm) shall be provided between the gas-tight capping slab of the heater and a combustible ceiling. clearances shall conform to TRVB 105.

      2. When masonry heaters are listed and labeled in accordance with UL 1482 maybe and installed in accordance with the listing, specifications and manufacturer's written instructions, clearances shall be as listed.

Add new standard to Chapter 44 as follows:

TRVB 105 - Fireplaces for Solid Fuels

Reason: Make masonry heater clearances safe and rational!

North American masonry heater technology is virtually all sourced in Europe where the devices have been built for centuries. In conformance with typical European standards, ASTM E1602, Standard Guide for Construction of Solid Fuel Burning Masonry Heaters, does not stipulate masonry heater wall thickness nor relate it to clearances to combustibles. In contrast to masonry fireplace construction and operation, masonry heater wall thickness is not the critical design feature but instead material thermal conductivity. Greater wall thicknesses actually create a more dangerous situation by creating more thermal storage with eventual radiation.

Heat storing masonry heaters are being designed and installed at the same clearances as fireplaces which are not designed to store heat. Until recent IBC and IRC code revisions, all minimum masonry heater clearances were 4" (102 mm) to surface wall or protective shield as per ASTM E1602. Although I can locate no documented examples of wall ignition from masonry heaters of any wall thickness at this clearance:

    1. no European country allows this low of a clearance for any masonry heater without testing and listing or a safety shielding strategy for clearance reduction.
    2. no UL 1482 testing exists for any masonry heater with this low of a clearance.
    3. ASTM E1602 mentions safety shielding but gives no prescription for use.
    4. TRVB 105 remedies this by establishing greater safety clearances and outlining reduction strategies.

In the recent IBC/IRC code revision "NFPA 211, Section 8-7 (clearances for solid fuel-burning appliances)" (sic) was made a ruling standard for masonry heater clearances instead of ASTM E1602:
    1. this standard was created for wood stoves and similar appliances and not masonry heaters.
    2. no European country stipulates masonry heater clearances to combustibles anywhere near 36".
    3. UL 1482 masonry heater testing is not yielding clearances anywhere near 36".
    4. NFPA 211 has recently moved masonry heaters from the chapter on solid fuel burning appliances to their own chapter, recognizing the difference in the devices.

The typical masonry heater sold is custom in design and cannot support laboratory safety testing. We cannot expect that such units will be listed. TRVB 105 is a consensus document from the experts in the technology and is the more conservative of such European standards.

Cost Impact: The code change proposal will not increase the cost of construction.



Public Hearing: Committee: D - on motion by Bob Eugene, UL

Assembly: ASF AMF DF

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