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Clearances to Combustible Side Walls
The minimum distance required from the edge of the unit to a combustible side wall is 18
”.
Combustible side walls, mantel
corbels, mantel legs and other combustible walls and decorative objects must fall behind a 45-degree line extending
outward from the edge of the unit unless such objects are more than 18
” away
from the edge of the unit.
If the required clearance cannot be m et to a pre-existing combustible side wall, an NFPA approved clearance
reduction shield, metal or ceramic board, must be added to the side wall.
Horizontal Clearance Reduction by 66%
NFPA 211 Approved
: Install 20-gauge or heavier steel s
hield that provides at least a 1”
active airspace, on the combustible wall
surface. To provide for active airflow, install at least 1” metal or ceramic standoffs or spacers between the metal shield a
nd the
combustible surface being protected. The bottom and top edges of the cavity between the metal shield and the combustible
surface must be left open. The steel
shield must be a minimum of 12”
larger in each direction than the surface area of the
source of heat; or if the surface being protected is smaller than surface area of the source of heat, this shield must be larger
than the combustible surface in each direction.
By using this method of protection, if the required horizontal clearance was 16
”
, the resulting clearance will be reduced by 66%
to 5-3/8
” between the heat source and the metal shield.
Horizontal Clearance Reduction by 50%
NFPA 211 Approved
: Install an R-1 rated ceramic board or R-1 rated mineral board on the wall you are attempting to protect.
by using this method of protection, if the required horizontal clearance was 16
”
, the resulting clearance will be reduced by 50%
to 8
” between the heat source and the
R-1 Rated wall board.
