20
Appendi
xI
For installations regulated by the International Residential Code, the
support foundation for the fireplace
installed
on
concrete
shal
l
consist
of
am
inimum
of6i
nche
st
hick
reinforced
concrete slab. The minimum specified compressive strength of
f’
c
,s
hall
be
as
required in Table R402.2 of t
he International Residential Code (IRC). Concrete subject to
moderate or severe weatherin
g as indi
cated
in Figure R301.2(3) of the
International Residential Code (IRC) shall be air en
trained
as
specified
in
Tabl
eR
402.
2o
ft
he
International
Residential
Code
(IRC).
The
maxi
mum weight of fly ash, other pozzolans, silica fume, slag or blended cement
s that is included
in
concrete
mixtures for garage
floor slabs and for exterior porch
es
, carport slabs and steps that will
be exposed
to deicin
gc
hemica
ls
shall not exceed the percentages of the total weight of cementitious
materials specified
in Section 4.2.3 of ACI 318. Materials
used to
produc
ec
oncrete
and
testin
gt
hereo
fs
hall
comply
with
th
ea
pplicable stand
ards listed in Chapter 3 of ACI 318.
For installations regulated by the International Building Code
(IBC), the support foundation for the fireplace installed on co
ncrete
shall c
onsist 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 Internat
ional Building Code (IBC)
.
TABLE R402.2 MINIMUM SPECIFIED COM
PRESSIVE STRENGTH OF CONCRETE
MINIMUM
SPECIFIED
COMPRESSIVE
STRENGTH
a
(
f’
c
)
Weathering Potentia
l
b
TYPE
OR
LOCATION
OF
CONCRETE CONSTRUCTION
Negligible
Moderate
Severe
Basement walls, foundations and othe
r concrete
not
exposed
to
th
ew
eather
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,
foundatio
nw
alls,
exterio
r walls and other vertical concre
te
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
slab
s2
,500
3,000
d,e,
f
3,500
d,e,
f
a.
Strengt
ha
t2
8d
ay
sp
si.
b.
Se
eF
igur
eR
301.2(3)
fo
rw
eathering potential.
c.
Concrete
in
these
location
st
ha
tm
ay
be
subject to freezing and thawing during construc
tion shall
be
air-entrained
concrete in
accordanc
e
with
Footnote
d.
d.
Concrete
shall
be
air-entr
ained
.T
otal
air
conten
t(
percent
by
volu
me of c
oncrete) shall be not less than 5 percent or
more
th
an
7 percent.
e.
See
Section
R402.2
for
maximu
mc
ementitious
materials
content.
f.
For
garag
ef
loor
sw
ith
a
steel
troweled
finish, reduction of
th
et
otal
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.