Isokern Standard 36 - Height Requirements; DM Chimney System

40
DM Chimney System: Height Requirements
Chimney Height Requirement:
The required minimum chimney height above the roof
and adjacent walls and buildings is specied 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 67)
(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 68)
(3) In all cases, the chimney cannot be less than 3’ above the roof
at the edge of the chimney. (Figure 67 & 68)
A simple example of this would be if the roof is at
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 69)
Note: The “2 foot in 10 foot rule” is necessary in the interest
of re safety but does not ensure smoke-free operation of the
replace. Trees, buildings, adjoining roof lines, adverse wind
conditions, etc. may require a taller chimney for the replace 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.
WARNING: Keep all insulation minimum of three inches (3”)
away from all DM chimney components. If insulation is used
in walls surrounding the chimney, insulation may be installed
behind sheathing of gypsom board, plywood, particle board or
other material on the side facing the Isokern material. The facing
material cannot be within 1 1/2” to the chimney outer casing.
Failure to use manufacture’s provided parts or variations in
techniques and construction materials or practices other than
those described in this manual may create a re hazard and void
the limited warranty. Do not pack insulation around the replace
or chimney. Do not insulate the chase cavity with blown or loose-
ll type insulation materials.
Chase Top Flashings:
Non-combustible, weather tight chase ashing 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 ashing for
positive weather seal. Chase ashings may be supplied by others.
FIGURE 69
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
FIGURE 67
FIGURE 68