Isokern Standard 36 - Non Combustible Finished Facing Requirements & Clearance to Combustible Trim

14”
8”
12"
26"
4"8"
20"
12”
COMBUSTIBLE
MANTLE SHELF
20” HEARTH
EXTENSION
COMBUSTIBLE
FLOOR SYSTEM
ADJOINING
ROOM WALL
HEARTH
EXTENSION
Non-combustible Finished Facing Requirements &
Clearance to Combustible Trim
Hearth Extensions:
All Fireplaces shall have hearth extensions of brick,
concrete, stone, tile or other code approved noncombustible
material. Suitable hearth extension material for the replaces
shall be placed on the hearth extension’s noncombustible
substrate and must extend to at least twenty inches (20”) in
front of the replace’s nished opening and must extend to
at least twelve inches (12”) beyond the sides of the nished
replace opening. (Figure 41)
WARNING: The noncombustible hearth extension, by code,
must sit on noncombustible substrate which shall have no
wood underpinnings.
This means that off-grade wood oor systems shall be
constructed in such a way that all wood oor joists and
subooring shall stop twenty inches (20”) out from the front of
the rebox. (Figure 40)
Mantle and Mantle Shelf Clearances: Fireplaces are subject
to the same building code safety clearances to combustible
trim as with any radiant heat replace.
All combustible trim shall be kept at least eight inches
(8”) from the nished replace opening.
Combustible trim located along the sides of the
replace opening, which project more than one and one-
half inches (1-1/2”) from the face of the replace, shall have
additional clearance from the eight inches (8”) equal to the
projection.
Combustible projecting mantles - up to twelve inches
(12”) of projection - shall not be placed less than fouteen
inches (14”) from the top of the replace opening. Combustible
mantles which project more than twelve inches (12”) from the
face of the replace, shall have additional clearance from the
fourteen inches (14”) equal to the projection.
Note: The local authority having jurisdiction may require
greater clearances for projecting combustible mantle shelves.
Be sure to check local building codes regarding required
clearances to projecting combustible mantles.
Adjoining Walls. Side walls and walls to rooms adjoining
replace installations cannot be closer than twenty-six inches
(26”) to the nished replace opening. (Figure 41)
Note: “Clearance to Combustible Trim” are those distances
required to ensure that a replace mantle or facing will not
catch re. In most cases the distances should also be adequate
to prevent any discoloration or warping due to heat. However
each installation presents a unique and completely different set
of circumstances involving many variables.
These include paint or nish composition, previous
exposure to heat, methods and quality of construction, air ow
patterns, etc. Because of these variables, the manufacturer does
not guarantee that heat warping or discoloration will never
occur.
27
FIGURE 40
FIGURE 41