An information series from the national authority on concrete masonry technology

FIRE RESISTANCE RATINGS

OF CONCRETE MASONRY TEK 7-1C
ASSEMBLIES Fire Resistance (2009)

INTRODUCTION METHODS OF DETERMINING FIRE

RESISTANCE RATINGS
Concrete masonry is widely specified for fire walls
and fire barriers because concrete masonry is noncombus- Because full-scale fire testing of representative test
tible, provides durable fire resistance, and is economical specimens is not practical in daily practice due to time
to construct. and financial constraints, the IBC outlines multiple op-
Chapter 7 of the International Building Code (IBC) tions for alternatives for fire rating determination:
(refs. 2, 3) governs materials and assemblies used for • standardized calculation procedures, such as those in
structural fire resistance and fire-rated separation of the Standard and in Section 721 of the IBC,
adjacent spaces. This TEK is based on the provisions of • prescriptive designs such as those in Section 720 of
Code Requirements for Determining Fire Resistance of the IBC,
Concrete and Masonry Construction Assemblies, ACI • engineering analysis based on a comparison with tested
216.1/TMS-0216 (ref. 1) (hereafter referred to as the assemblies, and
Standard), which outlines a procedure to calculate the fire • third party listing services, such as Underwriters Labo-
resistance ratings of concrete masonry assemblies. The ratory,
1997 edition of the Standard is referenced in the 2003 and • alternative means approved by the building official per
2006 IBC for concrete and masonry materials. The current Section 104.11 of the IBC.
edition of the Standard, published in 2007, contains only Of these, the calculation method is an economical
minor changes from the 1997 edition and is referenced and commonly used method of determining concrete
in the 2009 IBC. IBC sections 721.3 through 721.5 are masonry fire resistance ratings. The calculations are based
nearly identical to the provisions of the Standard. on extensive research, which established relationships
This TEK is based on both prescriptive details and between the physical properties of materials and the fire
tables as well as the calculated fire resistance procedure, resistance rating. The calculation method is fully described
which is practical, versatile and economical. The cal- in the Standard and IBC Section 721, and determines fire
culation procedure allows the designer virtually unlim- resistance ratings based on the equivalent thickness of
ited flexibility to incorporate the excellent fire-resistive concrete masonry units and the aggregate types used in
properties of concrete masonry into the design. Included their manufacture.
are methods for determining the fire resistance rating of Private commercial listing services allow the designer
concrete masonry walls, columns, lintels, beams, and to select a fire rated assembly that has been previously
concrete masonry fire protection for steel columns. Also tested, classified and listed in a published directory of
included are assemblies composed of concrete masonry fire rated assemblies. The listing service also monitors
and other components, including plaster and gypsum materials and production to verify that the concrete ma-
wallboard finishes, and multi-wythe masonry components sonry units are and remain in compliance with appropriate
including clay or shale masonry units. standards, which usually necessitates a premium for units

Related TEK: Keywords: calculated fire resistance rating, columns, control joints,
2-6, 5-8B, 7-6A equivalent thickness, fire resistance ratings, fire walls, lintels, multi-wythe
walls, specifications, steel column protection

NCMA TEK 7-1C 1

of this type. The system also is somewhat inflexible in
that little variation from the original tested wall assem-
bly is allowed, including unit size, shape, mix design,
constituent materials, and even the plant of manufacture.
For prescriptive designs, the IBC provides a series of
. ) 4.0 the equivalent
tables that describes requirements of various assemblies
5 8 in thickness is
to meet the fire resistance ratings specified. The last two
53% solid 7 mm (103 4 in.
unit 4 mm 4.04 inches
options listed above require justification to the building (19 ) (103 mm)
official that the proposed design is at least the equivalent
of what is prescribed in the code. The equivalent thickness (a solid unit with the same
amount of material) of this particular unit is 4.04 in.
CALCULATED FIRE RESISTANCE RATINGS (103 mm).

Background Figure 1—Equivalent Thickness

The calculated fire resistance method is based on
extensive research and testing of concrete masonry walls.
Fire testing of wall assemblies is conducted in accordance
with the Standard Test Methods for Fire Tests of Building
Construction and Materials, ASTM E119 (ref. 4), which Table 2—Equivalent Thicknesses of
measures four performance criteria, as follows: Concrete Masonry Units, in. (mm)
• resistance to the transmission of heat through the wall
assembly, Nominal Based on Based on
• resistance to the passage of hot gases through the wall, width, in. typical percent solid
sufficient to ignite cotton waste, (mm) hollow unitsA (75%) (100%)
• load-carrying capacity of loadbearing walls, and 4 (102) 2.7 (69) [73.8] 2.7 (69) 3.6 (91)
• resistance to the impact, erosion and cooling effects 6 (152) 3.1 (79) [55.0] 4.2 (107) 5.6 (142)
of a hose stream on the assembly after exposure to the 8 (203) 4.0 (102) [53.0] 5.7 (145) 7.6 (193)
10 (254) 4.5 (113) [46.3] 7.2 (183) 9.6 (244)
standard fire.
12 (305) 5.1 (129) [44.0] 8.7 (221) 11.6 (295)
The fire resistance rating of concrete masonry is typi-
14 (356) 5.5 (139) [40.2] 10.2 (259) 13.6 (345)
cally governed by the heat transmission criteria. From the 16 (406) 6.0 (152) [38.4] 11.7 (297) 15.6 (396)
standpoint of life safety (particularly for fire fighters) and
salvageability, this failure mode is certainly preferable A
Values in brackets [ ] are percent solid values based on
to a structural collapse endpoint, characteristic of many typical two-core concrete masonry units.
other building materials.

Table 1—Fire Resistance Rating Period of Concrete Masonry Assemblies (refs. 1, 2, 3)

Aggregate type in the Minimum required equivalent thickness, in. (mm), for fire resistance rating, hoursA, B
concrete masonry unitC 4 33/4 31/2 31/4 3 23/4 21/2 21/4 2 13/4 11/2 11/4 1 3
/4 1/2
Calcareous or siliceous gravel 6.2 6.0 5.8 5.5 5.3 5.0 4.8 4.5 4.2 3.9 3.6 3.2 2.8 2.4 2.0
Limestone, cinders or 5.9 5.7 5.5 5.2 5.0 4.8 4.5 4.3 4.0 3.7 3.4 3.1 2.7 2.3 1.9
unexpanded slag
Expanded clay, shale or slate 5.1 4.9 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.3 2.9 2.6 2.2 1.8
Expanded slag or pumice 4.7 4.5 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.7 2.5 2.1 1.9 1.5

A
Fire resistance rating between the hourly fire resistance rating periods listed may be determined by linear interpolation
based on the equivalent thickness value of the concrete masonry unit. The requirements of ASTM C55, ASTM C73, ASTM
C90 or ASTM C744 (refs. 13, 14, 6, 15) shall apply. Include equivalent thickness of finishes where applicable: see section
“Effects of Finishes on Fire Resistance Ratings.”
B
Where combustible members are framed into the wall, the thickness of solid material between the end of each member and op-
posite wall face, or between members set in from opposite sides, must be at least 93% of thickness shown.
C
Minimum required equivalent thickness corresponding to the hourly fire resistance rating for units made with a combina-
tion of aggregates shall be determined by linear interpolation based on the percent by volume of each aggregate used in
the manufacture.

2 NCMA TEK 7-1C

 The calculated fire resistance rating information pre- Tr = required equivalent thickness for a specific fire
sented here is based on the IBC and the Standard (refs. resistance rating of an assembly constructed of units
1, 2, 3). with combined aggregates, in. (mm)
T1, T2, ...Tn = required equivalent thickness from Table
Equivalent Thickness 1 for a specific fire resistance rating of a wall con-
Extensive testing has established a relationship be- structed of units with aggregate types 1, 2, ... n,
tween fire resistance and the equivalent solid thickness of respectively, in. (mm)
concrete masonry walls, as shown in Table 1. Equivalent V1, V2, ... Vn = fractional volume of aggregate types 1, 2,
thickness is essentially the solid thickness that would be ... n, respectively, used in the manufacture of the unit
obtained if the volume of concrete contained in a hollow (note that the clarification "dry-rodded volume" was
unit were recast without core holes (see Figure 1). The added to the 2007 edition of the Standard, although
equivalent thickness is determined in accordance with this verbiage not included in the IBC)
Standard Methods of Sampling and Testing Concrete Ma-
sonry Units, ASTM C140 (ref. 5), and is reported on the Blended aggregate example:
C140 test report. If the equivalent thickness is unknown, The required equivalent thickness of an assembly
but the percent solid of the unit is, the equivalent thick- constructed of units made with expanded shale (80% by
ness of a hollow unit can be determined by multiplying volume), and calcareous sand (20% by volume), to meet
the percent solid by the unit's actual thickness. a 3-hour fire resistance rating is determined as follows.
The equivalent thickness of a 100% solid unit or a From Table 1:
solid grouted unit is equal to the actual thickness. For T1 for expanded shale (3 hr rating)
partially grouted walls where the unfilled cells are left = 4.4 in. (112 mm)
empty, the equivalent thickness for fire resistance rating T2 for calcareous sand (3 hr rating)
purposes is equal to that of an ungrouted unit. For partially = 5.3 in. (135 mm)
grouted walls with filled cells, see the following section.
Loadbearing units conforming to ASTM C90 (ref. 6) Tr = (T1 x V1) + (T2 x V2)
that are commonly available include 100% solid units, Tr = (4.4 x 0.80) + (5.3 x 0.20)
75% solid units, and hollow units meeting minimum re- = 4.6 in. (116 mm)
quired face shell and web dimensions. Typical equivalent
thickness values for these units are listed in Table 2. Multi-Wythe Wall Assemblies
The fire resistance rating of multi-wythe walls (Figure
Filling Cells with Loose Fill Material 2) is based on the fire resistance of each wythe and the air
If all cells of hollow unit masonry are filled with an space between each wythe using the following equation:
approved material, the equivalent thickness of the assem- R = (R10.59 + R20.59 +...+Rn0.59 + A1 + A2 +... An)1.7
bly is the actual thickness. This also applies to partially where:
grouted concrete masonry walls where all ungrouted cells R1, R2,...Rn = fire resistance rating of wythe 1, 2,...n,
are filled with an approved material. respectively (hr).
Applicable fill materials are: grout, sand, pea gravel, A1, A2,...An = 0.30; factor for each air space, 1, 2,...n,
crushed stone, or slag that comply with ASTM C33 (ref. respectively, having a width of 1/2 in. (13 mm)
7) requirements; pumice, scoria, expanded shale, expanded or more between wythes. Note that it does not
clay, expanded slate, expanded slag, expanded fly ash, or matter which side is exposed to the fire.
cinders that comply with ASTM C331 (ref. 8), perlite meet- For multi-wythe walls of clay and concrete masonry,
ing the requirements of ASTM C549 (ref. 9), or vermiculite use the values in Table 3 for the brick wythe in the above
complying with C516 (ref. 10). equation.

Wall Assembly Fire Ratings Reinforced Concrete Masonry Columns

The fire resistance rating is determined in accordance Concrete masonry column fire testing evaluates the
with Table 1 utilizing the appropriate aggregate type used ability of the column to carry design loads under standard
in the masonry unit and the equivalent thickness. fire test conditions. Based on a compendium of fire tests,
Units manufactured with a combination of aggregate the fire resistance rating of reinforced concrete masonry
types are addressed by footnote C, which may be expressed columns is based on the least plan dimension of the
by the following equation (see also the blended aggregate column as indicated in Table 4. The minimum required
example, below): cover over the vertical reinforcement is 2 in. (51 mm).
Tr = (T1 x V1) + (T2 x V2) + ... + (Tn x Vn), where:

NCMA TEK 7-1C 3

Concrete Masonry Lintels in Table 1 would correspond to the carbonate or siliceous
Fire testing of concrete masonry beams and lintels aggregate concrete curve and the last two aggregate catego-
evaluates the ability of the member to sustain design loads ries of Table 1 would correspond to the semi-lightweight
under standard fire test conditions. This is accomplished or lightweight concrete curve. For example, for an 8-in.
by ensuring that the temperature of the tensile reinforce- (203-mm) limestone aggregate concrete masonry wall
ment does not exceed 1,100 oF (593 oC) during the rating with a maximum control joint width of 1/2 in. (13 mm), a
period. 1 in. (25 mm) thickness (measured perpendicular to the
The calculated fire resistance rating of concrete ma- face of the wall) of ceramic fiber in the joint can be used
sonry lintels is based on the nominal thickness of the lintel in walls with fire resistance ratings up to 3 hours, while
and the minimum cover of longitudinal reinforcement (see a 2 in. (51 mm) thickness can be used in the joints of a
Table 5). The cover requirements protect the reinforcement 4-hour wall.
from strength degradation due to excessive temperature
during the fire exposure period. Cover requirements may Steel Columns Protected by Concrete Masonry
be provided by masonry units, grout, or mortar. Note that Fire testing of a steel column protected by concrete
for 3 and 4 hour requirements, not enough cover is avail- masonry evaluates the structural integrity of the steel
able for 6-in. (152 mm) masonry. However, if a special column under fire test conditions, by measuring the tem-
analysis indicates that the reinforcement is not necessary perature rise of the steel. The calculated fire resistance
or not needed, such as when conditions for arching action
are present, the cover requirements may be waived. See Table 3—Fire Resistance of Brick or Tile of Clay
TEK 17-1C (ref. 12) for lintel design and conditions for or Shale (refs. 1, 2, 3)
arching action.
Minimum equivalent thicknessA for
Control Joints fire resistance rating, in. (mm)
Figure 3 shows control joint details in fire-rated wall Material type 4 hr 3 hr 2 hr 1 hr
assemblies in which openings are not permitted or where > 75% solid 6.0 (152) 4.9 (124) 3.8 (97) 2.7 (69)
openings are required to be protected. Maximum joint Hollow unitsB 5.0 (127) 4.3 (109) 3.4 (86) 2.3 (58)
width is 1/2 in. (13 mm). Although these details are not Hollow unitsC 6.6 (168) 5.5 (140) 4.4 (112) 3.0 (76)
directly in the IBC, they are included by reference of the
Standard. A
See Equivalent Thickness section for calculation.
In addition to these prescriptive fire resistance rated B
Unfilled hollow units.
control joints, other control joints may be permitted in fire C
Grouted or filled according to the Filling Cells with Loose
rated masonry walls. For example, the IBC and the Standard Fill Material section.
include provisions for ceramic fiber joint protection for
precast panels, which are similar to concrete masonry walls
in that both rely on concrete for fire protection, and both Table 4—Reinforced Concrete Masonry Columns
are governed by the ASTM E119 heat transmission criteria (refs. 1, 2, 3)
(see Figure 4). The first two categories of aggregate types
Minimum column dimensions, in. (mm),
for fire resistance rating of:
1 hour 2 hours 3 hours 4 hours
Wythe (R2 ) Air space factor(A1) 8 (203) 10 (254) 12 (305) 14 (356)
for widths12 in.
(13 mm) or greater Table 5—Reinforced Concrete Masonry Lintels
Minimum Longitudinal Reinforcing Cover,
in. (mm) (refs. 1, 2, 3)
Nominal
lintel width, Fire resistance rating
in., (mm) 1 hour 2 hours 3 hours 4 hours
Wythe (R ) 6 (152) 11/2 (38) 2 (51) A A

8 (203) 1 /2 (38) 1 /2 (38) 1 /4 (44) 3 (76)

1 1 3

R1 = Fire resistance rating of wythe 1 10 (254) or more 11/2 (38) 11/2 (38) 11/2 (38) 13/4 (44)
R 2 = Fire resistance rating of wythe 2
A1 = Air space factor = 0.3 A
May be permitted with a more detailed analysis
per the Standard –i.e. conditions for arching action.
Figure 2—Variables for Determining the Fire
Resistance Rating of a Multi-Wythe Masonry Wall

4 NCMA TEK 7-1C

rating of steel columns protected by concrete masonry,
as illustrated in Figure 5, is determined by:
0.7 Vertical reinforcement,
W   T 1.5  Joint reinforcement, as required
R = 0.17   +  0.285 e0.2  × as required
D  K 
  ( As )  
0.8

    Stop joint
  d mTe  
1.0 + 42.7  0.25 p + T   ( English units )
reinforcement
at control joint Preformed
  e 
 gasket
   
 Concrete masonry sash unit
0.7
W   T 1.5

R=1.22   + 0.0018 e
0.2 × Sealant Backer rod
D  K 
2-Hour Fire Resistance Rating
  ( As )  
0.8

    Joint reinforcement,
  d mTe  
1.0 + 384  0.25 p + T   ( SI )
as required
  e 

 
   Vertical

Stop joint reinforcement,
reinforcement at as required
where: control joint
Ceramic fiber
dm= density of concrete masonry protection, pcf (kg/m3) felt (alumina-
D = heated perimeter of steel, in. (mm) (Figure 5) silica fiber)
K = thermal conductivity of concrete masonry, Table
6, Btu/hr.ft.oF (W/m.C) Sealant Backer rod
p = inner perimeter of concrete masonry protection,
in. (mm) Joint reinforcement,
as required
R = fire resistance rating of column assembly, hr.
Te = equivalent thickness of masonry protection, in.
(mm) Stop joint
Vertical
reinforcement,
W = average weight of steel column in lb/ft (kg/m) reinforcement
as required
at control joint
Note: The Standard (ref. 1) has a slightly different form Raked mortar
of the equation but yields identical answers. For more Building paper joint
or other
information on steel columns protected by concrete bond break
masonry, see TEK 7-6A, Steel Column Fire Protection
Backer rod
(ref. 11). Sealant

Effects of Finish Materials on Fire Resistance Joint reinforcement, Female concrete

as required masonry unit
Ratings
In many cases, drywall, plaster or stucco finishes
are used on concrete masonry walls. While finishes are Male concrete
Stop joint masonry unit
normally applied for architectural reasons, they can also reinforcement at
provide additional fire resistance. The IBC and the Standard control joint
Raked mortar
make provision for calculating the additional fire resistance joint, 1 2 in. (13 mm)
provided by these finishes. min. depth
Note that when finishes are used to achieve the required
fire rating, the masonry alone must provide at least one- Sealant Backer rod

half of the total required rating and the contribution of the

finish on the non-fire-exposed side can not be more than Three Options for 4-Hour Fire Resistance Rating
one-half of the contribution of the masonry alone. This
is to assure structural integrity during a fire. The finish Figure 3—Control Joints for Fire Resistant
material must also be continuous over the entire wall. Concrete Masonry Assemblies (ref. 1)
Certain finishes deteriorate more rapidly when
exposed to fire than when they are on the non-fire side

NCMA TEK 7-1C 5

4 4 of the wall. Therefore, two
C, ceramic blanket thickness, in.
1 in.1(25.4 mm)mm)
in. (25.4 joint joint
widthwidth 1 in. (25.4 mm) maximum
1 in. (25.4 mm) maximum separate tables are required.

4
regardless of opening Table 7 applies to finishes on
of opening
regardless

hr

hr
3 3 ratingrating the non-fire-exposed side of
the wall, and Table 8 applies to

3 4

3
hr h

hr
Ceramic fiber fiber finishes on the fire-exposed side.

43
Ceramic

3h

hrhr
2 2 blanket

r
blanket

r
2 2 For finishes on the non-fire-
2
hr h r hr h 2
r exposed side of the wall, the fin-

Panel thickness

Panel thickness
ish is converted to an equivalent

"C" thickness of ceramic blanket, in.

"C" thickness of ceramic blanket, in.

1 1
1 hr 1 h C thickness of concrete masonry
r C
1 hr 1 by multiplying the finish thick-
hr
0 0 ness by the factor given in Table
3 3 4 4 5 5 6 6 7 7 8 8 7. The result, Tef, is then added
Panel thickness, in.
Panel thickness, in. to the concrete masonry wall
C, ceramic blanket thickness, in.

Joint width
Joint width equivalent thickness, Te, and
3 3 3
8 in.3 (9.5 mm) joint width used in Table 1 to determine
8 in. (9.5 mm) joint width
the wall's fire resistance rating
3 hr 3 hr 2 hr 2 hr (i.e., the equivalent thickness of
2
2 concrete masonry assemblies,
Carbonate or siliceous Tea = Te + Tef).
4 r
3

1 Carbonate or siliceous For finishes on the fire-

4
hr
3
hr

1 aggregate concrete
hr
h

2h aggregate concrete
1

exposed side of the wall, a time

4

r 2h
1
hr r

4
hr

r
hr r
1

hr

(from Table 8) is assigned to

1
h

0 Semi-lightweight or
h

0 Semi-lightweight the finish. This time is added

3
3
4
4
5
5
6
6
7
7
8
8 lightweight concrete or
Panel thickness, in. lightweight concrete to the fire resistance rating de-
Panel thickness, in. termined for the base wall and
non-fire-exposed side finish, if
Figure 4—Ceramic Fiber Joint Protection
any. The times listed in Table 8
are essentially the length of time
the various finishes will remain intact when exposed to
fire (i.e., on the fire-exposed side of the wall).
When calculating the fire resistance rating of a wall
with finishes, two calculations are performed, assuming
w d each side of the wall is the fire-exposed side. The fire

Table 6—Concrete Masonry

d Conductivity (refs. 2, 3)
tweb
Density, dm Thermal conductivityA, K
pcf (kg/m3) Btu/hr.ft.oF (W/m.C)
ps = 2(w + d) + 2(w - tweb) ps = 4d 80 (1,281) 0.207 (0.358)
85 (1,362) 0.228 (0.394)
d 90 (1,442) 0.252 (0.436)
95 (1,522) 0.278 (0.481)
100 (1,602) 0.308 (0.533)
105 (1,682) 0.340 (0.588)
110 (1,762) 0.376 (0.650)
0.25p 115 (1,842) 0.416 (0.720)
ps = πd
120 (1,922) 0.459 (0.749)
125 (2,002) 0.508 (0.879)
130 (2,082) 0.561 (0.971)
135 (2,162) 0.620 (1.073)
0.25p 140 (2,243) 0.685 (1.186)
145 (2,323) 0.758 (1.312)
Figure 5—Details of Concrete Masonry Column 150 (2,403) 0.837 (1.449)
Protection for Commonly Used Shapes A
Thermal conductivity at 70 F. C = (oF-32)(5/9)
o o

6 NCMA TEK 7-1C

rating of the wall assembly is the lower of the two. Typi- Some of these materials have not been evaluated using
cally, for an exterior wall with a fire separation distance standardized fire resistance test methods or have been
greater than 5 ft (1,524 mm), fire needs be considered evaluated only to a limited degree. Such unconventional
on the interior side only. materials, which are typically used as a replacement for
conventional aggregates, may not be covered within
Installation of Finishes existing codes and standards due to their novelty or
Finishes that contribute to the total fire resistance proprietary nature.
rating of a wall must meet certain minimum installation While test methods such as ASTM E119 define pro-
requirements. Plaster and stucco are applied in accordance cedures for evaluating the fire resistance properties of
with the provisions of the building code without further concrete masonry assemblies, including those constructed
modification. using unconventional constituent materials, there has
Gypsum wallboard and gypsum lath are to be attached historically been no defined procedure for applying the
to wood or metal furring strips spaced a maximum of 16 results of ASTM E119 testing to standardized calculation
in. (406 mm) o.c., and must be installed with the long procedures available through the Standard. To provide
dimension parallel to the furring members. All horizontal consistency in applying the results of full-scale ASTM
and vertical joints must be supported and finished. E119 testing to established calculation procedures, NCMA
has developed a guideline for this purpose, available
UNCONVENTIONAL AGGREGATES for download through the technical FAQ portion of the
NCMA website (www.ncma.org).
In recent years, manufacturers of concrete masonry
products have been exploring the use of alternative
materials in the production of concrete masonry units. Table 8—Time Assigned to Finish Materials on
Fire-Exposed Side of Wall (refs. 1, 2, 3)
Table 7—Multiplying Factor for Finishes on
Non-Fire-Exposed Side of Wall (refs. 2, 3)A Finish description: Time, min.
Aggregate type in concrete masonry: Gypsum wallboard
Siliceous, 80% or more by 3/8 in. (10 mm) 10
calcareous, volume of 1/2 in. (13 mm) 15
Type of finish limestone, expanded shale, 5/8 in. (16 mm) 20
applied to cinders, air- slate, or clay, Two layers of 3/8 in. (10 mm) 25
wall cooled blast- expanded slag One layer 3/8 in. (10 mm) and
furnace slag or pumice one layer 1/2 in. (13 mm) 35
Portland cement- Two layers of 1/2 in. (13 mm) 40
sand plaster 1.00 0.75B, D Type "X" gypsum wallboard
Gypsum-sand 1/2 in. (13 mm) 25
plaster 1.25 1.00 5/8 in. (16 mm) 40
Gypsum- Direct-applied portland cement-sand
vermiculite or 1.75 1.25C plaster A
perlite plaster Portland cement-sand plaster on
Gypsum metal lath
wallboardA 3.00 2.25 3/4 in. (19 mm) 20
A
Values shown are 2009 IBC & ACI 216.1/TMS 216-07. Note 7/8 in. (22 mm) 25
that in the 2006 IBC, gypsum wallboard was included in the 1 in. (25 mm) 30
same category and had the same values as for gypsum-sand Gypsum-sand plaster on 3/8 in. (10 mm)
plaster. However, the 2006 IBC also indicated that ACI gypsum lath
216.1/TMS 216-97 could be used, which is as shown here. 1/2 in. (13 mm) 35
B
For portland cement-sand plaster 5/8 in. (16 mm) or less in 5/8 in. (16 mm) 40
thickness and applied directly to concrete masonry on the 3/4 in. (19 mm) 50
non-fire-exposed side, the multiplying factor is 1.0. Gypsum-sand plaster on metal lath
C
For expanded shale with less than 20% sand, a multiplying 3/4 in. (19 mm) 50
factor of 1.50 may be used per 2009 IBC. 7/8 in. (22 mm) 60
D
For 100% expanded slag, expanded clay or pumice, and 1 in. (25 mm) 80
portland cement-sand plaster not meeting the stipulations
A
For the purposes of determining the contribution of
of footnote B, the multiplying factor shall be 0.50 per 2009 portland cement-sand plaster to the equivalent thickness
IBC. of concrete masonry for use in Table 1, use either the
actual plaster thickness or 5/8 in. (16 mm), whichever
is smaller.

NCMA TEK 7-1C 7

 This guideline stipulates that when applying the of units produced with such aggregates to be calculated for
fire resistance calculation procedure of the Standard to interpolated values of equivalent thickness and proportion
products manufactured using aggregate types that are of non-listed aggregate.
not listed in the Standard, at least two full-scale ASTM
E119 tests must be conducted on assemblies containing
the unconventional material. Based on the results of this
testing, an expression can be developed in accordance
with this industry practice that permits the fire resistance

REFERENCES

1. Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies, ACI 216.1-
07/TMS-0216-07. American Concrete Institute and The Masonry Society, 2007.
2. International Building Code 2009. International Code Council, 2009.
3 International Building Code 2006. International Code Council, 2006.
4. Standard Test Methods for Fire Tests of Building Construction and Materials, ASTM E119-08a. ASTM International,
Inc., 2008.
5. Standard Methods for Sampling and Testing Concrete Masonry Units, ASTM C140-08a. ASTM International, Inc.,
2008.
6. Standard Specification for Loadbearing Concrete Masonry Units, ASTM C90-09. ASTM International, Inc., 2009.
7. Standard Specification for Concrete Aggregates, ASTM C33-08. ASTM International, Inc., 2008.
8. Standard Specification for Lightweight Aggregates for Concrete Masonry Units, ASTM C331-05. ASTM International,
Inc., 2005.
9. Standard Specification for Perlite Loose Fill Insulation, ASTM C549-06. ASTM International, Inc., 2006.
10. Standard Specification for Vermiculite Loose Fill Thermal Insulation, ASTM C516-08. ASTM International, Inc.,
2008.
11 . Steel Column Fire Protection, TEK 7-6A. National Concrete Masonry Association, 2009.
12. Allowable Stress Design of Concrete Masonry Lintels, TEK 17-1C. National Concrete Masonry Association, 2009.
13. Standard Specification for Concrete Building Brick, ASTM C55-06e1. ASTM International, Inc., 2006.
14. Standard Specification for Calcium Silicate Brick (Sand-Lime Brick), ASTM C73-05. ASTM International, Inc.,
2005.
15. Standard Specification for Prefaced Concrete and Calcium Silicate Masonry Units, ASTM C744-08. ASTM
International, Inc., 2008.

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