AskCodeMan

We have a proposal to install a new EPA phase II qualified fireplace but the manufacturer requires a 24" clearance from the side of the fuel loading door to a sidewall. They are proposing 3.5" masonry wall with an 1" air gap in an attempt to reduce the clearance requirement. My understanding is that NFPA 12.6.2 would allow this clearance requirement to be reduced to not less than 12". Would you concur is there more to it that I am missing? Thanks.

After reviewing NFPA 211 and 12.6.2, I would say that you are correct.

FIGURE 12.6.2.1(e) Wall Protection Using Materials in Table 12.6.2.1. shows that Material (b) and Materials (c) through (h) could be used to get to the 12" minimum clearance - however, looking back at Table 12.6.2.1 shows that Material (b) requires a minimum clearance of 18" ... which seems to be a conflict within NFPA 211, at least as I am reading it.

Thus using Materials (c) through (h) would solve that conflict as those materials meet a more restrictive requirement, and whenever there is a conflict, the most restrictive takes precedence.

Material:

(c) 0.024-in. (0.61-mm), 24-gauge sheet metal over 1-in. (25.4-mm) glass fiber or mineral wool batts reinforced with wire, or equivalent, on rear face with ventilated air space

(d) 31⁄2 in. (90 mm) thick masonry wall with ventilated air space

(e) 0.024-in. (0.61-mm), 24-gauge sheet metal with ventilated air space

(f) 1⁄2 in. (13 mm) thick noncombustible insulation board with ventilated air space

(g) 0.024-in. (0.61-mm), 24-gauge sheet metal with ventilated air space over 0.024-in. (0.61-mm), 24-gauge sheet metal with ventilated air space

(h) 1-in. (25.4-mm) glass fiber or mineral wool batts sandwiched between two sheets 0.024-in. (0.61-mm), 24-gauge sheet metal with ventilated air space