17
Appendix
I
For installations regulated by the International Residential Code, the
support foundation for the fireplace
installed
on
concrete
shal
l
consist
of
a
m
inimum
of
6
inches
thick
reinforced
concrete slab. The minimum specified compressive strength of
f’
c
,s
ha
llb
e
as
required in Table R402.2 of the International Residential Code (IRC). Concrete subject to
moderate or severe weathering as indi
cated
in Figure R301.2(3) of the International Residential Code (IRC) shall be air entrained
as
specified
in
Table
R402.2
of
the
Internationa
l
Residential
Code
(IRC).
The
maxi
mum weight of fly ash, other pozzolans, silica fume, slag or blended cements that is included
in
concrete
mixtures for garage floor slabs and for exterior porch
es, carport slabs and steps that will
be exposed
to deicing
chemical
s
shall not exceed the percentages of the total weight of cementitious
materials specified
in Section 4.2.3 of ACI 318. Materials
used to
produce
concrete
and
testing
thereo
f
shall
comply
with
the
applicable standards listed in Chapter 3 of ACI 318.
For installations regulated by the International Building Code (IBC), the support foundation for the fireplace installed on con
crete
shall consist of a minimum of 6 inches thick reinforced concrete
slab. The concrete
strength and durability shall comply with S
ections
1903, 1904 and 1905 of the International Building Code (IBC).
TABLE R402.2 MINIMUM SPECIFIED COMPRESSIVE STRENGTH OF CONCRETE
MINIMUM
SPECIFIED
COMPRESSIVE
STRENGTH
a
(
f’
c
)
Weathering Potential
b
TYPE
OR LOCATION OF
CONCRETE CONSTRUCTION
Negligible
Moderate
Severe
Basement walls, foundations and other concrete
not
exposed
to
the
weather
2,500
2,500
2,500
c
Basement slabs and interior slabs on grade, except garage floor slabs
2,500
2,500
2,500
c
Basement
walls,
foundation
w
alls,
exterior
walls and other vertical concrete
work exposed to the weather
2,500
3,000
d
3,000
d
Porches, carport slabs and steps exposed to the weather, and
garage
floor
slabs
2,500
3,000
d,e,
f
3,500
d,e,
f
a.
Strength
at
28
days
psi.
b.
See
Figure
R301.2(3)
for
w
eathering potential.
c.
Concrete
in
these
locations
that
m
ay
be
subject to freezing and thawing during construction shall
be
air-entrained
concrete in
accordance
with
Footnote
d.
d.
Concrete
shall
be
air-entrained.
Total
air
conten
t(percent
by
volu
me of concrete) shall be not less than 5 percent or
more tha
n
7 percent.
e.
S
ee
S
ec
ti
on
R
40
2.
2 f
or
m
ax
im
um
ce
m
en
ti
ti
ou
s
m
at
er
ia
ls
c
on
te
nt
.
f.
For
garage
floors
w
ith
a
steel
troweled
finish, reduction of
the
total
air
content (percent by volume of concrete) to not less than
3 percen
ti
s permitted
if
the specified
compressive strength of the concrete is increased to not less than 4,000 psi.