10’-0”
LESS THAN 10’-0”
CRICKET
3’-0” MIN
ROOF RIDGE
WORK POINT
SECTION
THRU ROOF
CHIMNEY
2’-0”
WORK
POINT
CRICKET
CHIMNEY
3’-0” MIN
SECTION
THRU ROOF
2’-0”
3’-0” MIN
48
DM Chimney System: Height Requirements
Chimney Height Requirement:
The required minimum chimney height above the roof
and adjacent walls and buildings is specified by all major building
codes and is summed up in what is known as “the 2 foot in 10 foot
rule”:
(1) If the horizontal distance from the roof ridge to the opening
of the chimney is less than 10’, the top of the chimney must be at
least 2’ above the roof ridge (Figure 99).
(2) If the horizontal distance from the opening of the chimney
to the roof ridge is more than 10’ then a chimney height “work
point” is established on the roof surface 10’ horizontally from the
opening of the chimney. The top of the chimney must be at least
2’ above this work point (Figure 100).
(3) In all cases, the chimney cannot be less than 3’ above the roof
at the edge of the chimney (Figures 99 & 100).
A simple example of this would be if the roof is flat
then the chimney would need to be at least 3’ above the roof
surface. Or, if the chimney penetrates the roof at the ridge then
the chimney must be at least 3’ above the ridge. (Figure 101)
Note:
The “2 foot in 10 foot rule” is necessary in the interest
of fire safety but does not ensure smoke-free operation of the
fireplace. Trees, buildings, adjoining roof lines, adverse wind
conditions, etc. may require a taller chimney for the fireplace to
draft properly.
Chase Enclosures:
DM chimneys can be enclosed within a
wood framed chase at zero clearance to wood framing members.
Chase enclosures need to be built to local wind load requirements
and shall be structurally independent of the Isokern chimney. As
with all chimney installations, avoid overhead obstructions such
as trees, power lines, etc.
CAUTION:
If insulation is used in chase walls the fireplace and
chimney must not be placed directly against it and must be kept
a minimum 3” from all fireplace and chimney components. It is
recommended that where fireplace and chimney chases are
insulated or have vapor barriers that the inside face of the chase
first be covered with gypsum board, plywood, particle board
or other sheathing material to assure that insulation and vapor
barriers remain in place and a minimum 3” away from the unit.
WARNING:
Do not pack insulation around the Standard
fireplace or chimney. Do not insulate the chase cavity with blown
or loose-fill type insulation materials.
Chase Top Flashings:
Non-combustible, weather tight chase flashing must be
used to cover the top of the chimney chase. Be sure to seal the
joint where the DM liner passes through the chase top flashing for
positive weather seal. Chase flashings may be supplied by others.
FIGURE 99
FIGURE 100
FIGURE 101
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