Heat, Air, and Moisture Control in Building Assemblies—Material Properties
Table 1
Licensed for single user. © 2021 ASHRAE, Inc.
Description
26.11
Building and Insulating Materials: Design Valuesa (Continued)
Density,
lb/ft3
Conductivityb k, Resistance R, Specific Heat,
Btu/lb·°F Referenceo
Btu·in/h·ft2 ·°F h·ft2 ·°F/Btu
12 in., 50 lb, 125 lb/ft3 concrete, 2 cores .......................
—
—
Medium-weight aggregate (combinations of normal and lightweight aggregate)
—
—
8 in., 26 to 29 lb, 97 to 112 lb/ft3 concrete, 2 or 3 cores
with perlite-filled cores............................................
—
—
with vermiculite-filled cores....................................
—
—
with molded-EPS-filled (beads) cores .....................
—
—
with molded EPS inserts in cores ............................
—
—
Lightweight aggregate (expanded shale, clay, slate or slag, pumice)
—
—
6 in., 16 to 17 lb, 85 to 87 lb/ft3 concrete, 2 or 3 cores .
with perlite-filled cores............................................
—
—
with vermiculite-filled cores....................................
—
—
—
—
8 in., 19 to 22 lb, 72 to 86 lb/ft3 concrete ......................
with perlite-filled cores............................................
—
—
with vermiculite-filled cores....................................
—
—
with molded-EPS-filled (beads) cores .....................
—
—
with UF foam-filled cores........................................
—
—
with molded EPS inserts in cores ............................
—
—
—
—
12 in., 32 to 36 lb, 80 to 90 lb/ft3, concrete, 2 or 3 cores
with perlite-filled cores............................................
—
—
with vermiculite-filled cores....................................
—
—
Stone, lime, or sand..............................................................
180
72
Quartzitic and sandstone......................................................
160
43
140
24
120
13
Calcitic, dolomitic, limestone, marble, and granite .............
180
30
160
22
140
16
120
11
100
8
Gypsum partition tile
3 by 12 by 30 in., solid...................................................
—
—
4 cells................................................
—
—
4 by 12 by 30 in., 3 cells ................................................
—
—
Limestone.............................................................................
150
3.95
163
6.45
Concretesi
Sand and gravel or stone aggregate concretes .....................
150
10.0 to 20.0
(concretes with >50% quartz or quartzite sand have
140
9.0 to 18.0
conductivities in higher end of range)
130
7.0 to 13.0
Lightweight aggregate or limestone concretes ....................
120
6.4 to 9.1
expanded shale, clay, or slate; expanded slags; cinders;
100
4.7 to 6.2
80
3.3 to 4.1
pumice (with density up to 100 lb/ft3); scoria (sanded
60
2.1 to 2.5
concretes have conductivities in higher end of range)
40
1.3
Gypsum/fiber concrete (87.5% gypsum, 12.5% wood chips)
51
1.66
Cement/lime, mortar, and stucco .........................................
120
9.7
100
6.7
80
4.5
Perlite, vermiculite, and polystyrene beads .........................
50
1.8 to 1.9
40
1.4 to 1.5
30
1.1
20
0.8
Foam concretes ....................................................................
120
5.4
100
4.1
80
3.0
70
2.5
Foam concretes and cellular concretes ................................
60
2.1
40
1.4
20
0.8
Aerated concrete (oven-dried) ............................................. 27 to 50
1.4
Polystyrene concrete (oven-dried) ....................................... 16 to 50
2.54
Polymer concrete .................................................................
122
11.4
138
7.14
Polymer cement ...................................................................
117
5.39
Slag concrete........................................................................
60
1.5
80
2.25
100
3
125
8.53
1.23
0.22
Valore (1988)
1.71 to 1.28
3.7 to 2.3
3.3
3.2
2.7
—
—
—
—
—
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
1.93 to 1.65
4.2
3.0
3.2 to 1.90
6.8 to 4.4
5.3 to 3.9
4.8
4.5
3.5
2.6 to 2.3
9.2 to 6.3
5.8
—
—
—
—
—
—
—
—
—
—
—
—
0.21
—
—
—
—
—
—
—
—
—
—
—
0.19
—
—
—
0.19
—
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
Van Geem (1985)
Shu et al. (1979)
Shu et al. (1979)
Shu et al. (1979)
Shu et al. (1979)
Van Geem (1985)
Van Geem (1985)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
1.26
1.35
1.67
—
—
0.19
—
—
0.2
0.2
Rowley and Algren (1937)
Rowley and Algren (1937)
Rowley and Algren (1937)
Kumaran (2002)
Kumaran (2002)
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0.19 to 0.24
—
—
0.2
0.2
—
—
0.2
—
—
—
—
0.15 to 0.23
—
—
—
—
—
—
—
—
—
0.2
0.2
—
—
—
—
—
—
—
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Rowley and Algren (1937)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Valore (1988)
Kumaran (1996)
Kumaran (1996)
Kumaran (1996)
Kumaran (1996)
Kumaran (1996)
Touloukian et al (1970)
Touloukian et al. (1970)
Touloukian et al. (1970)
Touloukian et al. (1970)
26.12
2021 ASHRAE Handbook—Fundamentals
Licensed for single user. © 2021 ASHRAE, Inc.
Table 1 Building and Insulating Materials: Design Valuesa (Continued)
Description
Density,
lb/ft3
Woods (12% moisture content)l
Hardwoods
Oak.......................................................................................
Birch.....................................................................................
Maple ...................................................................................
Ash .......................................................................................
Softwoods
Southern pine .......................................................................
Southern yellow pine ...........................................................
Eastern white pine................................................................
Douglas fir/larch ..................................................................
Southern cypress ..................................................................
Hem/fir, spruce/pine/fir .......................................................
Spruce ..................................................................................
Western red cedar ................................................................
West coast woods, cedars ....................................................
Eastern white cedar ..............................................................
California redwood ..............................................................
Pine (oven-dried) .................................................................
Spruce (oven-dried) .............................................................
—
41 to 47
43 to 45
40 to 44
38 to 42
—
36 to 41
31
25
34 to 36
31 to 32
24 to 31
25
22
22 to 31
23
24 to 28
23
25
Conductivityb k, Resistance R, Specific Heat,
Btu/lb·°F Referenceo
Btu·in/h·ft2 ·°F h·ft2 ·°F/Btu
—
1.12 to 1.25
1.16 to 1.22
1.09 to 1.19
1.06 to 1.14
—
1.00 to 1.12
1.06 to 1.16
0.85 to 0.94
0.95 to 1.01
0.90 to 0.92
0.74 to 0.90
0.74 to 0.85
0.83 to 0.86
0.68 to 0.90
0.82 to 0.89
0.74 to 0.82
0.64
0.69
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0.39n
—
—
—
—
0.39 n
—
—
—
—
—
—
—
—
—
—
—
0.45
0.45
Wilkes (1979)
Cardenas and Bible (1987)
Cardenas and Bible (1987)
Cardenas and Bible (1987)
Cardenas and Bible (1987)
Wilkes (1979)
Cardenas and Bible (1987)
Kumaran (2002)
Kumaran (2002)
Cardenas and Bible (1987)
Cardenas and Bible (1987)
Cardenas and Bible (1987)
Kumaran (2002)
Kumaran (2002)
Cardenas and Bible (1987)
Kumaran (2002)
Cardenas and Bible (1987)
Kumaran (1996)
Kumaran (1996)
Notes for Table 1
aValues are for mean temperature of 75°F. Representative values for dry materials are intended
kVinyl
as design (not specification) values for materials in normal use. Thermal values of insulating
materials may differ from design values depending on in situ properties (e.g., density and
moisture content, orientation, etc.) and manufacturing variability. For properties of specific
product, use values supplied by manufacturer or unbiased tests.
bSymbol  also used to represent thermal conductivity.
cDoes not include paper backing and facing, if any. Where insulation forms boundary (reflective or otherwise) of airspace, see Tables 2 and 3 for insulating value of airspace with appropriate effective emittance and temperature conditions of space.
dConductivity varies with fiber diameter (see Chapter 25). Batt, blanket, and loose-fill mineral fiber insulations are manufactured to achieve specified R-values, the most common of
which are listed in the table. Because of differences in manufacturing processes and materials, the product thicknesses, densities, and thermal conductivities vary over considerable
ranges for a specified R-value.
eValues are for aged products with gas-impermeable facers on the two major surfaces. An
aluminum foil facer of 0.001 in. thickness or greater is generally considered impermeable to
gases. For change in conductivity with age of expanded polyisocyanurate, see SPI Bulletin
U108.
fCellular phenolic insulation may no longer be manufactured.
gInsulating values of acoustical tile vary, depending on density of board and on type, size, and
depth of perforations.
hValues for fully grouted block may be approximated using values for concrete with similar
unit density.
iValues for concrete block and concrete are at moisture contents representative of normal use.
jValues for metal or vinyl siding applied over flat surfaces vary widely, depending on ventilation of the airspace beneath the siding; whether airspace is reflective or nonreflective; and
on thickness, type, and application of insulating backing-board used. Values are averages for
use as design guides, and were obtained from several guarded hot box tests (ASTM Standard C1363) on hollow-backed types and types made using backing of wood fiber, foamed
plastic, and glass fiber. Departures of ±50% or more from these values may occur.
lSee
assembly. As discussed previously, low air permeance is not sufficient to ensure a reliable air barrier assembly: the system must be
properly fastened and supported (on both sides) to resist wind loads,
and all materials must be durable for the expected service life of the
assembly. The air barrier must also be continuous, and should be
installed in such a way as to discourage wind washing (i.e., air
movement that reduces the thermal resistance of insulation layers in
the assembly).
4.5
WATER VAPOR PERMEANCE DATA
Table 5 gives typical water vapor permeance and permeability
values for common building materials. These values can be used to
specific heat = 0.25 Btu/lb·°F
Adams (1971), MacLean (1941), and Wilkes (1979). Conductivity values
listed are for heat transfer across the grain. Thermal conductivity of wood varies
linearly with density, and density ranges listed are those normally found for wood
species given. If density of wood species is not known, use mean conductivity
value. For extrapolation to other moisture contents, the following empirical equation developed by Wilkes (1979) may be used:
–2
–4
 1.874  10 + 5.753  10 M 
k = 0.1791 + --------------------------------------------------------------------------------1 + 0.01M
where  is density of moist wood in lb/ft3, and M is moisture content in percent.
mDimension
referenced is taken at the maximum siding profile thickness. The
range of R values and associated thicknesses represent values for products tested
to ASTM Standard D7793, which requires applying 15 mph airstream perpendicular to surface of siding during testing.
nFrom
Wilkes (1979), an empirical equation for specific heat of moist wood at
75°F is as follows:
 0.299 + 0.01M 
c p = ---------------------------------------- + c p
 1 + 0.01M 
where cp accounts for heat of sorption and is denoted by
c p = M  1.921  10
–3
–5
– 3.168  10 M 
where M is moisture content in percent by mass.
oBlank
space in reference column indicates historical values from previous volumes of ASHRAE Handbook. Source of information could not be determined.
calculate water vapor flow through building components and assemblies using equations in Chapter 25.
Water vapor permeability of most building materials is a function
of moisture content, which, in turn, is a function of ambient relative
humidity. Permeance values at various relative humidities are presented in Table 6 for several building materials. Figure 4 depicts the
increase in permeability with increasing relative humidity for oriented strand board (OSB) and plywood samples (Kumaran 2002).
Users of the dew-point method may use constant values found in
Table 5. However, if condensation in the assembly is predicted, then
a more appropriate value should be used. Transient hygrothermal
modeling typically uses vapor permeability values that vary with
relative humidity. Vapor permeability of homogeneous materials
Heat, Air, and Moisture Control in Building Assemblies—Material Properties
26.13
Table 2 Emissivity of Various Surfaces and Effective
Emittances of Facing Air Spacesa
Effective Emittance eff of
Air Space
Licensed for single user. © 2021 ASHRAE, Inc.
Surface
Aluminum foil, bright
Aluminum foil, with
condensate just visible
(>0.7 g/ft2)
Aluminum foil, with
condensate clearly visible
(>2.9 g/ft2)
Aluminum sheet
Aluminum-coated paper,
polished
Brass, nonoxidized
Copper, black oxidized
Copper, polished
Iron and steel, polished
Iron and steel, oxidized
Lead, oxidized
Nickel, nonoxidized
Silver, polished
Steel, galvanized, bright
Tin, nonoxidized
Aluminum paint
Building materials: wood,
paper, masonry, nonmetallic
paints
Regular glass
Average One Surface’s
Both
Emissivity Emittance ;
Surfaces’

Other, 0.9
Emittance 
0.05
0.05
0.03
0.30b
0.29
—
0.70b
0.65
—
0.12
0.12
0.06
0.20
0.20
0.11
0.04
0.74
0.04
0.2
0.58
0.27
0.06
0.03
0.25
0.05
0.50
0.038
0.41
0.038
0.16
0.35
0.21
0.056
0.029
0.24
0.047
0.47
0.02
0.59
0.02
0.11
0.41
0.16
0.03
0.015
0.15
0.026
0.35
0.90
0.82
0.82
0.84
0.77
0.72
Fig. 4 Permeability of Wood-Based Sheathing Materials at
Various Relative Humidities
apply in 4 to 40 m range of electromagnetic spectrum. Also, oxidation, corrosion, and accumulation of dust and dirt can dramatically increase surface emittance.
Emittance values of 0.05 should only be used where the highly reflective surface can
be maintained over the service life of the assembly. Except as noted, data from VDI
(1999).
bValues based on data in Bassett and Trethowen (1984).
aValues
can be calculated from thickness and vapor permeance (as given in
Table 6).
4.6
MOISTURE STORAGE DATA
Transient analysis of assemblies requires consideration of the
materials’ moisture storage capacity. Some materials (hygroscopic)
adsorb or reject moisture to achieve equilibrium with adjacent air.
Storage capacity of these materials is typically shown by graphs of
moisture content versus humidity. The curve showing uptake of
moisture (the sorption isotherm) is usually above the curve showing drying (the desorption isotherm) because the material’s uptake
and release of moisture are inhibited by surface tension. Table 7 provides data for these curves for several hygroscopic materials, and
Kumaran (1996, 2002) and McGowan (2007) provide actual curves,
additional data, and conditions under which they were determined.
Table 7 expresses moisture content as percentage of dry weight,
followed by a subscript value of the relative air humidity at which
this moisture content occurs. Note that these values are based on
measurement of materials that have reached equilibrium with their
surroundings, which in some cases can take many weeks. Most
hygrothermal simulation software programs that use these values
assume that equilibrium is achieved instantaneously.
Maximum values in Table 7 are those that could be realistically
measured in laboratory conditions, so not all materials have a listing
for maximum moisture content at 100% relative humidity. For those
that do, there may be two listings: the moisture content measured
when the material’s capillary pores were saturated (shown as 100c),
Fig. 5 Sorption/Desorption Isotherms, Cement Board
and the value at total saturation (shown as 100t). Note that the moisture content of any material is 0.0 at a theoretical relative humidity
of 0%, so this point is not shown in the table.
Figure 5 shows an example of a conventional sorption isotherm
graph. Curves show sorption (wetting) and desorption (drying) for
data in Table 7 and from Kumaran (2002). (Data from Table 7 were
selectively used to provide an accurate representation of the
sorption isotherm; not all data from the original source are represented.)
4.7
SOILS DATA
Apparent soil thermal conductivity is difficult to estimate and
may change in the same soil at different times because of changed
moisture conditions and freezing temperatures.
Figure 6 shows typical apparent soil thermal conductivity as a
function of moisture content for different general types of soil. The
figure is based on data presented in Salomone and Marlowe (1989)
using envelopes of thermal behavior coupled with field moisture
content ranges for different soil types. In Figure 6, “well graded”
applies to granular soils with good representation of all particle
sizes from largest to smallest. “Poorly graded” refers to granular
soils with either uniform gradation, in which most particles are
about the same size, or skip (or gap) gradation, in which particles of
one or more intermediate sizes are not present.
26.14
2021 ASHRAE Handbook—Fundamentals
Effective Thermal Resistance of Plane Air Spaces,a,b,c h·ft2 ·°F/Btu
Air Space
Effective Emittance effd,e
Table 3
Position of
Air Space
Horiz.
Licensed for single user. © 2021 ASHRAE, Inc.
45°
Slope
Vertical
45°
Slope
Horiz.
Direction of
Heat Flow
Temp.
Mean
Temp.d, °F Diff.,d °F
0.03
0.5 in. Air Spacec
0.05
0.2
0.5
0.82
0.03
0.75 in. Air Spacec
0.05
0.2
0.5
0.82
Up
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.13
1.62
2.13
1.73
2.10
1.69
2.04
2.03
1.57
2.05
1.70
2.04
1.66
2.00
1.51
1.29
1.60
1.45
1.70
1.49
1.75
0.99
0.96
1.11
1.12
1.27
1.23
1.40
0.73
0.75
0.84
0.91
1.00
1.04
1.16
2.34
1.71
2.30
1.83
2.23
1.77
2.16
2.22
1.66
2.21
1.79
2.16
1.74
2.11
1.61
1.35
1.70
1.52
1.78
1.55
1.84
1.04
0.99
1.16
1.16
1.31
1.27
1.46
0.75
0.77
0.87
0.93
1.02
1.07
1.20
Up
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.44
2.06
2.55
2.20
2.63
2.08
2.62
2.31
1.98
2.44
2.14
2.54
2.04
2.56
1.65
1.56
1.83
1.76
2.03
1.78
2.17
1.06
1.10
1.22
1.30
1.44
1.42
1.66
0.76
0.83
0.90
1.02
1.10
1.17
1.33
2.96
1.99
2.90
2.13
2.72
2.05
2.53
2.78
1.92
2.75
2.07
2.62
2.01
2.47
1.88
1.52
2.00
1.72
2.08
1.76
2.10
1.15
1.08
1.29
1.28
1.47
1.41
1.62
0.81
0.82
0.94
1.00
1.12
1.16
1.30
Horiz.
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.47
2.57
2.66
2.82
2.93
2.90
3.20
2.34
2.46
2.54
2.72
2.82
2.82
3.10
1.67
1.84
1.88
2.14
2.20
2.35
2.54
1.06
1.23
1.24
1.50
1.53
1.76
1.87
0.77
0.90
0.91
1.13
1.15
1.39
1.46
3.50
2.91
3.70
3.14
3.77
2.90
3.72
3.24
2.77
3.46
3.02
3.59
2.83
3.60
2.08
2.01
2.35
2.32
2.64
2.36
2.87
1.22
1.30
1.43
1.58
1.73
1.77
2.04
0.84
0.94
1.01
1.18
1.26
1.39
1.56
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.48
2.64
2.67
2.91
2.94
3.16
3.26
2.34
2.52
2.55
2.80
2.83
3.07
3.16
1.67
1.87
1.89
2.19
2.21
2.52
2.58
1.06
1.24
1.25
1.52
1.53
1.86
1.89
0.77
0.91
0.92
1.15
1.15
1.45
1.47
3.53
3.43
3.81
3.75
4.12
3.78
4.35
3.27
3.23
3.57
3.57
3.91
3.65
4.18
2.10
2.24
2.40
2.63
2.81
2.90
3.22
1.22
1.39
1.45
1.72
1.80
2.05
2.21
0.84
0.99
1.02
1.26
1.30
1.57
1.66
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.48
2.66
2.67
2.94
2.96
3.25
3.28
2.34
2.54
2.55
2.83
2.85
3.15
3.18
1.67
1.88
1.89
2.20
2.22
2.58
2.60
1.06
1.24
1.25
1.53
1.53
1.89
1.90
0.77
0.91
0.92
1.15
1.16
1.47
1.47
3.55
3.77
3.84
4.18
4.25
4.60
4.71
3.29
3.52
3.59
3.96
4.02
4.41
4.51
2.10
2.38
2.41
2.83
2.87
3.36
3.42
1.22
1.44
1.45
1.81
1.82
2.28
2.30
0.85
1.02
1.02
1.30
1.31
1.69
1.71
1.5 in. Air Spacec
Air Space
Horiz.
45°
Slope
Vertical
Up
Up
Horiz.
3.5 in. Air Spacec
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.55
1.87
2.50
2.01
2.43
1.94
2.37
2.41
1.81
2.40
1.95
2.35
1.91
2.31
1.71
1.45
1.81
1.63
1.90
1.68
1.99
1.08
1.04
1.21
1.23
1.38
1.36
1.55
0.77
0.80
0.89
0.97
1.06
1.13
1.26
2.84
2.09
2.80
2.25
2.71
2.19
2.65
2.66
2.01
2.66
2.18
2.62
2.14
2.58
1.83
1.58
1.95
1.79
2.07
1.86
2.18
1.13
1.10
1.28
1.32
1.47
1.47
1.67
0.80
0.84
0.93
1.03
1.12
1.20
1.33
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
2.92
2.14
2.88
2.30
2.79
2.22
2.71
2.73
2.06
2.74
2.23
2.69
2.17
2.64
1.86
1.61
1.99
1.82
2.12
1.88
2.23
1.14
1.12
1.29
1.34
1.49
1.49
1.69
0.80
0.84
0.94
1.04
1.13
1.21
1.35
3.18
2.26
3.12
2.42
2.98
2.34
2.87
2.96
2.17
2.95
2.35
2.87
2.29
2.79
1.97
1.67
2.10
1.90
2.23
1.97
2.33
1.18
1.15
1.34
1.38
1.54
1.54
1.75
0.82
0.86
0.96
1.06
1.16
1.25
1.39
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
3.99
2.58
3.79
2.76
3.51
2.64
3.31
3.66
2.46
3.55
2.66
3.35
2.58
3.21
2.25
1.84
2.39
2.10
2.51
2.18
2.62
1.27
1.23
1.45
1.48
1.67
1.66
1.91
0.87
0.90
1.02
1.12
1.23
1.33
1.48
3.69
2.67
3.63
2.88
3.49
2.82
3.40
3.40
2.55
3.40
2.78
3.33
2.75
3.30
2.15
1.89
2.32
2.17
2.50
2.30
2.67
1.24
1.25
1.42
1.51
1.67
1.73
1.94
0.85
0.91
1.01
1.14
1.23
1.37
1.50
Heat, Air, and Moisture Control in Building Assemblies—Material Properties
26.15
Table 3 Effective Thermal Resistance of Plane Air Spaces,a,b,c h·ft2 ·°F/Btu (Continued)
Air Space
Effective Emittance effd,e
Position of
Air Space
45°
Slope
Horiz.
Direction of
Heat Flow
Temp.
Mean
Temp.d, °F Diff.,d °F
0.03
1.5 in. Air Spacec
0.05
0.2
0.5
0.82
0.03
3.5 in. Air Spacec
0.05
0.2
0.5
0.82
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
5.07
3.58
5.10
3.85
4.92
3.62
4.67
4.55
3.36
4.66
3.66
4.62
3.50
4.47
2.56
2.31
2.85
2.68
3.16
2.80
3.40
1.36
1.42
1.60
1.74
1.94
2.01
2.29
0.91
1.00
1.09
1.27
1.37
1.54
1.70
4.81
3.51
4.74
3.81
4.59
3.77
4.50
4.33
3.30
4.36
3.63
4.32
3.64
4.32
2.49
2.28
2.73
2.66
3.02
2.90
3.31
1.34
1.40
1.57
1.74
1.88
2.05
2.25
0.90
1.00
1.08
1.27
1.34
1.57
1.68
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
6.09
6.27
6.61
7.03
7.31
7.73
8.09
5.35
5.63
5.90
6.43
6.66
7.20
7.52
2.79
3.18
3.27
3.91
4.00
4.77
4.91
1.43
1.70
1.73
2.19
2.22
2.85
2.89
0.94
1.14
1.15
1.49
1.51
1.99
2.01
10.07
9.60
11.15
10.90
11.97
11.64
12.98
8.19
8.17
9.27
9.52
10.32
10.49
11.56
3.41
3.86
4.09
4.87
5.08
6.02
6.36
1.57
1.88
1.93
2.47
2.52
3.25
3.34
1.00
1.22
1.24
1.62
1.64
2.18
2.22
Up
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
3.01
2.22
2.97
2.40
2,90
2.31
2.80
2.82
2.13
2.82
2.33
2.79
2.27
2.73
1.90
1.65
2.04
1.89
2.18
1.95
2.29
1.15
1.14
1.31
1.37
1.52
1.53
1.73
0.81
0.86
0.95
1.06
1.15
1.24
1.37
Up
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
3.26
2.19
3.16
2.35
3.00
2.16
2.78
3.04
2.10
2.99
2.28
2.88
2.12
2.71
2.00
1.64
2.12
1.86
2.24
1.84
2.27
1.19
1.13
1.35
1.35
1.54
1.46
1.72
0.83
0.85
0.97
1.05
1.16
1.20
1.37
Horiz.
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
3.76
2.83
3.72
3.08
3.66
3.03
3.59
3.46
2.69
3.49
2.95
3.49
2.95
3.47
2.17
1.97
2.36
2.28
2.59
2.44
2.78
1.25
1.28
1.44
1.57
1.70
1.81
2.00
0.86
0.93
1.01
1.17
1.25
1.42
1.53
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
4.90
3.86
4.93
4.24
4.93
4.28
4.93
4.41
3.61
4.52
4/-1
4.63
4.12
4.71
2.51
2.42
2.80
2.86
3.16
3.19
3.53
1.35
1.46
1.59
1.82
1.94
2.19
2.35
0.91
1.02
1.09
1.31
1.37
1.65
1.74
Down
90
50
50
0
0
–50
–50
10
30
10
20
10
20
10
11.72
10.61
12.70
12.10
13.80
12.45
14.60
9.24
8.89
10.32
10.42
11.65
11.14
12.83
3.58
4.02
4.28
5.10
5.38
6.22
6.72
1.61
1.92
1.98
2.52
2.59
3.31
3.44
1.01
1.23
1.25
1.64
1.67
2.20
2.26
5.5 in. Air Spacec
Licensed for single user. © 2021 ASHRAE, Inc.
Air Space
Horiz.
45°
Slope
Vertical
45°
Slope
Horiz.
Chapter 25. Thermal resistance values were determined from R = 1/C, where C = hc + εeff hr ,
hc is conduction/convection coefficient, εeff hr is radiation coefficient ≈ 0.0068εeff [(tm +
460)/100]3, and tm is mean temperature of air space. Values for hc were determined from data
developed by Robinson et al. (1954). Equations (5) to (7) in Yarbrough (1983) show data in this table in analytic form.
For extrapolation from this table to air spaces less than 0.5 in. (e.g., insulating window glass),
assume hc = 0.159(1 + 0.0016tm)/l, where l is air space thickness in in., and hc is heat transfer
through air space only.
bValues based on data presented by Robinson et al. (1954). (Also see Chapter 4, Tables 5 and 6,
and Chapter 33.) Values apply for ideal conditions (i.e., air spaces of uniform thickness bounded
by plane, smooth, parallel surfaces with no air leakage to or from the space). This table should
not be used for hollow siding or profiled cladding: see Table 1. For greater accuracy, use overall U-factors determined through guarded hot box (ASTM Standard C1363) testing. Thermal
resistance values for multiple air spaces must be based on careful estimates of mean temperature
differences for each air space.
aSee
cA
single resistance value cannot account for multiple air spaces; each air
space requires a separate resistance calculation that applies only for
established boundary conditions. Resistances of horizontal spaces with
heat flow downward are substantially independent of temperature difference.
d Interpolation is permissible for other values of mean temperature, temperature difference, and effective emittance eff. Interpolation and moderate extrapolation for air spaces greater than 3.5 in. are also permissible.
e Effective emittance  of air space is given by 1/ = 1/ + 1/  1,
eff
eff
1
2
where 1 and 2 are emittances of surfaces of air space (see Table 2).
Also, oxidation, corrosion, and accumulation of dust and dirt can
dramatically increase surface emittance. Emittance values of 0.05
should only be used where the highly reflective surface can be maintained over the service life of the assembly.
26.16
2021 ASHRAE Handbook—Fundamentals
Table 4 Air Permeability of Different Materials
Mean Air
Permeability,
lb/ft·h·in. Hg
Material
lb/ft3
Licensed for single user. © 2021 ASHRAE, Inc.
Cement board, 1/2 in., 71
Fiber cement board, 1/4 in., 86 lb/ft3
Gypsum wall board, 1/2 in., 39 lb/ft3
with one coat primer
with one coat primer/two coats latex paint
Hardboard siding, 3/8 in., 46 lb/ft3
Oriented strand board (OSB), 41 lb/ft3, 3/8 in.
7/16 in.
1/2 in.
Douglas fir plywood, 1/2 in., 29 lb/ft3
5/8 in., 34 lb/ft3
Canadian softwood plywood, 3/4 in., 28 lb/ft3
Wood fiber board, 3/8 in., 20 lb/ft3
Masonry Materials
Aerated concrete, 28.7 lb/ft3
Cement mortar, 100 lb/ft3
Clay brick, 4 by 4 by 8 in., 124 lb/ft3
Limestone, 156 lb/ft3
Portland stucco mix, 124 lb/ft3
Eastern white cedar, 3/4 in., 22 lb/ft3 (transverse)
0.24
0.00002
0.03
0.18
0.02
0.037
0.008
0.016
0.008
0.0003
0.008
0.0002
2.0
Table 4 Air Permeability of Different Materials
Mean Air
Permeability,
lb/ft·h·in. Hg
Material
Source: Kumaran (2002).
0.04
0.01
32
negligible
8.15E-05
negligible
Eastern white pine, 3/4 in., 29 lb/ft3 (transverse)
Southern yellow pine, 3/4 in., 31.2 lb/ft3
(transverse)
8.2E-06
0.00024
Fig. 6 Trends of Apparent Thermal Conductivity
of Moist Soils
Spruce, 3/4 in., 25 lb/ft3 (transverse)
Western red cedar, 3/4 in., 21.8 lb/ft3 (transverse)
Cellulose insulation, dry blown, 2 lb/ft3
Glass fiber batt, 1 lb/ft3
Polystyrene expanded, 1 lb/ft3
sprayed foam, 2.4 lb/ft3
0.4 to 1/2 lb/ft3
Polyisocyanurate insulation, 1.7 lb/ft3
Bituminous paper (#15 felt), 28 mil, 54 lb/ft2
(transverse)
0.00041
< 7E-06
2364
2038
0.09
0.000082
0.034
negligible
20
Although thermal conductivity varies greatly over the complete
range of possible moisture contents, this range can be narrowed if it
is assumed that the moisture contents of most field soils lie between
the wilting point of the soil (i.e., the moisture content of a soil
below which a plant cannot alleviate its wilting symptoms) and the
field capacity of the soil (i.e., the moisture content of a soil that has
been thoroughly wetted and then drained until the drainage rate has
become negligibly small). After a prolonged dry spell, moisture is
near the wilting point, and after a rainy period, soil has moisture
content near its field capacity. Moisture contents at these limits have
been studied by many agricultural researchers, and data for different
types of soil are given by Kersten (1949) and Salomone and Marlowe (1989). Shaded areas in Figure 6 approximate (1) the full range
of moisture contents for different soil types and (2) a range between
average values of each limit.
Table 8 summarizes design values for thermal conductivities of
the basic soil classes. Table 9 gives ranges of thermal conductivity
for some basic classes of rock. The value chosen depends on
whether heat transfer is calculated for minimum heat loss through
the soil, as in a ground heat exchange system, or a maximum value,
as in peak winter heat loss calculations for a basement. Hence, high
and low values are given for each soil class.
When calculating annual energy use, choose values that represent typical mean site conditions. In climates where ground freezing
is significant, accurate heat transfer simulations should include the
effect of the latent heat of fusion of water. Energy released during
this phase change significantly retards the progress of the frost front
in moist soils.
For further information, see Chapter 17, which includes a
method for estimating heat loss through foundations.
Asphalt-impregnated paper
#10, 5 mil, 5.9 lb/ft2 (transverse)
#30, 6 mil, 8.2 lb/ft2 (transverse)
#60, 9 mil, 16.1 lb/ft2 (transverse)
Spun bonded polyolefin (SBPO) 4 mil, 0.87/ft2
(transverse)
with crinkled surface, 3 to 4 mil, 0.92 lb/ft2
(transverse)
Wallpaper, vinyl, 5 mil, 5.9 lb/ft2 (transverse)
Exterior insulated finish system (EIFS), 0.17 in.
acrylic, 71 lb/ft3
9
54
58
4
2
0.041
0
As heat flows through soil, moisture tends to move away from
the heat source. This moisture migration provides initial mass transport of heat, but it also dries the soil adjacent to the heat source, thus
lowering the apparent thermal conductivity in that zone of soil.
Typically, when other factors are held constant, k increases with
moisture content and with dry density of a soil, but decreases with
increasing organic content of a soil and for uniform gradations and
rounded soil grains (because grain-to-grain contacts are reduced).
The k of a frozen soil may be higher or lower than that of the same
unfrozen soil (because the conductivity of ice is higher than that of
water but lower than that of typical soil grains). Differences in k
below moisture contents of 7 to 8% are quite small. At approximately
15% moisture content, k may vary up to 30% from unfrozen values.
4.8
SURFACE FILM COEFFICIENTS/
RESISTANCES
As explained in Chapter 25, the overall thermal resistance of an
assembly comprises its surface-to-surface thermal resistance Rs and
Heat, Air, and Moisture Control in Building Assemblies—Material Properties
26.17
Table 5 Typical Water Vapor Permeance and Permeability for Common Building Materialsa
Material
Weight,
lb/100 ft2
Plastic and Metal Foils and Filmsb
Aluminum foil
0.001
0.00035
0.002
0.004
0.006
0.008
0.010
0.002
0.004
0.001
0.0032
0.0076
0.01
0.125
Polyethylene
Polyvinylchloride, unplasticized
Polyvinylchloride, plasticized
Polyester
Licensed for single user. © 2021 ASHRAE, Inc.
Cellulose acetate
Liquid-Applied Coating Materials
Commercial latex paints (dry film thickness)
Vapor retarder paint
Primer-sealer
Vinyl acetate/acrylic primer
Vinyl/acrylic primer
Semigloss vinyl/acrylic enamel
Exterior acrylic house and trim
Paint, 2 coats
Asphalt paint on plywood
Aluminum varnish on wood
Enamels on smooth plaster
Primers and sealers on interior insulation board
Various primers plus 1 coat flat oil paint on plaster
Flat paint on interior insulation board
Water emulsion on interior insulation board
Paint, 3 coats
Exterior paint, white lead and oil on wood siding
Exterior paint, white lead/zinc oxide and oil on wood
Styrene/butadiene latex coating
Polyvinyl acetate latex coating
Chlorosulfonated polyethylene mastic
Asphalt cutback mastic
1/16 in., dry
3/16 in., dry
Hot-melt asphalt
Building Paper, Felts, Roofing Papersc
Duplex sheet, asphalt laminated, aluminum foil one side
Saturated and coated roll roofing
Kraft paper and asphalt laminated, reinforced
Blanket thermal insulation back-up paper, asphalt coated
Asphalt, saturated and coated vapor retarder paper
Asphalt, saturated, but not coated, sheathing paper
asphalt felt, 15 lb
tar felt, 15 lb
Single kraft, double
Polyamide film, 2 mil
Thickness,
in.
Permeance, perm
Dry-Cup
Wet-Cup
Other Method
Permeability,
perm-in.
3.2
3.2
3.2
3.2
3.2
3.2
0.0
0.05
0.16
0.08
0.06b
0.04b
0.68b
0.8 to 1.4
0.73
0.23
0.08
4.6
0.32
0.0031
0.0012
0.002
0.0016
0.0024
0.0017
0.45
6.28
7.42
8.62
6.61
5.47
0.4
0.3 to 0.5
0.5 to 1.5
0.9 to 2.15
1.6 to 3.0
4
30 to 85
12.5
25
21.9
43.8
0.3 to 1.0
0.9
11
5.5
1.7
0.06
12.5
21.9
0.14
0.0
0.5
0.1
8.6
65
6.8
6.2
8.6
4.4
14
14
3.2
0.002
0.05
0.3
0.4
0.2 to 0.3
3.3
1.0
4.0
31
1.10
Source: Lotz (1964).
aThis table allows comparisons of materials, but when selecting vapor retarder materials, exact values for permeance
or permeability should be obtained from manufacturer or from laboratory tests. Values shown indicate variations
among mean values for materials that are similar but of different density, orientation, lot, or source. Values should
not be used as design or specification data. Values from dry- and wet-cup methods were usually obtained from
investigations using ASTM Standards C355 and E96; other values were obtained by two-temperature, special cell,
and air velocity methods.
0.176
0.24
1.8
0.6 to 4.2
0.6
20.2
5.6
18.2
42
20.53
bUsually
installed as vapor retarders, although sometimes
used as exterior finish and elsewhere near the cold side,
where special considerations are then required for warmside barrier effectiveness.
cLow-permeance sheets used as vapor retarders. High permeance used elsewhere in construction.
26.18
2021 ASHRAE Handbook—Fundamentals
Table 6 Water Vapor Permeance at Various Relative Humidities and Capillary Water Absorption Coefficient
Licensed for single user. © 2021 ASHRAE, Inc.
Material
Building Board and Siding
Asbestos cement board
with oil-base finishes
Cement board, 71 lb/ft3
Fiber cement board, 86 lb/ft3
Gypsum board, asphalt impregnated
Gypsum wall board, 39 lb/ft3
with one coat primer
with one coat primer/two coats latex paint
Hardboard siding, 46 lb/ft3
Oriented strand board (OSB), 41 lb/ft3
41 lb/ft3
41 lb/ft3
Particleboard, 48 lb/ft3
Plywood
Douglas fir, 29 lb/ft3
Douglas fir, 34 lb/ft3
Canadian softwood, 28 lb/ft3
Exterior-grade, 36 lb/ft3
Thickness,
in.
Permeance at Various Relative Humidities, perm
10%
50%
70%
90%
13
3.6
17
10
22
32
0.16
0.31
56
38
7.0
7.5
0.86
2.0
1.3
3.8
2.1
65
50
14
8.2
2.4
3.7
2.4
4.9
4.6
78
62
29
9.0
6.7
6.6
3.9
8.6
9.4
0.023
0.28
4-8
0.3-0.5
10
1.3
40
47
26
3.6
6.9
0.31
0.97
0.49
4.0
0.86
0.59
0.70
0.48
0.18
0.06
0.37
0.48
0.56
0.38
1.3
2.2
0.53
3.4
6.0
1.7
9.3
13
11
Exterior-grade, 32 lb/ft3
Wood fiber board, 20 lb/ft3
19 lb/ft3
0.51
0.46
1
18
47
1.2
20
48
1.4
22
50
3.2
24
53
15
27
58
0.012
Masonry Materials
Aerated concrete, 29 lb/ft3
Cement mortar, 100 lb/ft3
Clay brick, 124 lb/ft3
Concrete, 138 lb/ft3
Concrete block (cored, limestone aggregate)
Lightweight concrete, 83 lb/ft3
Limestone, 156 lb/ft3
Perlite board, 10 lb/ft3
11 lb/ft3
0.80
0.51
0.49
1
8
1
1
1
1
14
22
6.2
0.9
20
27
6.7
1.0
2.4
29
33
7.2
1.7
43
40
7.7
4.5
0.44
0.25
2.1
0.22
7.8
0.18
23
44
13
0.18
56
44
14
2.9
16
4.0
0.15
Plaster, on metal lath
on wood lath
on plain gypsum lath (with studs)
Polystyrene concrete, 16-50 lb/ft3
Portland stucco mix, 124 lb/3
Tile masonry, glazed
Woods
Cedar
Eastern white cedar, 22 lb/ft3 (transverse)
Western red cedar, 22 lb/ft3 (transverse)
Pine
21 lb/ft3 (longitudinal)
Eastern white pine, 29 lb/ft3 (transverse)
Southern yellow pine, 31 lb/ft3 (transverse)
Sugar pine, 23 lb/ft3 (transverse)
Spruce
28 lb/ft3 (longitudinal)
26 lb/ft3 (transverse)
25 lb/ft3 (transverse)
Insulation
Air (still)
Cellular glass
Cellulose, dry blown, 1.9 lb/ft3
Corkboard
Glass fiber batt, 0.7 lb/ft3
0.12
30%
Water
Absorption
Coefficient,
lb/(ft2·h1/2)
0.5
0.31
0.5
0.5
0.43
0.39
0.43
0.48
0.75
0.47
10
0.46
41
12
1.9
6.3
0.01
0.04
0.06
9.6
18
5.8
44
8.4
0.18
19
44
0.75
0.18
44
15
11
20
13
2.0
0.12
0.0088
0.020
0.027
0.020
0.052
0.038
0.045
0.0041
References/Comments
Dry cup*
Dry cup*
Kumaran (2002)
Kumaran (2002)
Dry cup*
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Burch et al. (1992)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Burch and Desjarlais
(1995)
Burch et al. (1992)
Kumaran (2002)
Burch and Desjarlais
(1995)
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Kumaran (1996)
*
Kumaran (1996)
Kumaran (2002)
Kumaran (1996)
Burch and Desjarlais
(1995)
*
*
*
Kumaran (1996)
Kumaran (2002)
*
1
0.55
4
11
1.0
12
1.4
0.75
0.01
0.07
0.44
2.8
19
0.020
Kumaran (2002)
0.71
1
0.10
0.22
20
0.47
27
1.0
51
2.2
82
0.012
0.20
Kumaran (2002)
Kumaran (1996)
0.75
0.77
0.51
0.52
0.04
0.11
0.45
41
0.16
0.36
0.54
98
0.62
1.2
0.93
112
2.4
4.2
2.3
120
9.3
15
8.4
121
0.081
0.017
0.12
Kumaran (2002)
Kumaran (2002)
Burch et al. (1992)
Kumaran (1996)
0.45
0.77
0.34
1.1
0.96
2.1
2.8
8.6
8.3
30
26
0.025
Kumaran (1996)
Kumaran (2002)
1
1
2.5
1
3.5
30
34
38
2.1-2.6
34
120
0.0
42
34
45
9.5
34
48
34
1.2
*
*
Kumaran (2002)
*
Kumaran (2002)
Heat, Air, and Moisture Control in Building Assemblies—Material Properties
Table 6
Water Vapor Permeance at Various Relative Humidities and Capillary Water Absorption Coefficient (Continued)
Material
Thickness,
in.
Permeance at Various Relative Humidities, perm
Water
Absorption
Coefficient,
lb/(ft2·h1/2)
10%
30%
50%
70%
90%
0.93
145
145
145
145
145
0.065
0.004
0.01
0.04
0.12
0.35
Mineral fiber insulation, 9 to 11 lb/ft3
Mineral wool (unprotected)
Phenolic foam (covering removed)
Polyisocyanurate insulation, 1.7 lb/ft3
2.0 lb/ft3
1
1
1
1
0.97
87
87
87
87
2.8
2.0
3.1
2.3
87
116
26
3.5
2.5
4.0
2.8
4.5
3.2
Polyisocyanurate glass-mat facer, 27 lb/ft3
0.032
10
15
22
32
48
Polystyrene
expanded, 0.9 lb/ft3
extruded, 1.8 lb/ft3
Polyurethane
expanded board stock
sprayed foam, 2.4 lb/ft3
0.4 to 0.5 lb/ft3
Structural insulating board, sheathing quality
interior, uncoated
Unicellular synthetic flexible rubber foam
0.96
2.0
2.4
2.8
3.3
3.9
1
1
0.8
0.8
0.4-1.6
0.8
0.8
0.8
Kumaran (2002)
*
1
1
1
0.5
1
1.6
60
1.7
60
1.9
60
20-50
50-90
2.0
60
2.2
60
Kumaran (2002)
Kumaran (2002)
*
*
Dry cup*
0.0079
4.1
7.4
14
26
53
0.012
Kumaran (2002)
0.0087
0.013
0.028
0.002
0.0055
0.00390.0043
7.7
26
5.1
22
42
5.1
4.1
76
55
40
55
6.9
11
76
55
81
74
20
35
76
55
0.011
0.014
0.0063
76
55
13
33
5.1
0.93
76
55
0.0038
0.0029
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Gatland II (2005)
Kumaran (2002)
Kumaran (2002)
0.011
0.017-0.028
0.0081
1.5
86-120
11-20
2.4
3.7
250-380
160-500
5.5
8.0
0.0031
Kumaran (1996)
Kumaran (1996)
Kumaran (2002)
**
1.6
1.6
0.0
1.6
1.6
1.6
0.0065
*
Kumaran (2002)
Glass-fiber insulation board, 7.6 lb/ft3
facer, 55 lb/ft3
Licensed for single user. © 2021 ASHRAE, Inc.
26.19
Foil, Felt, Paper (transverse)
Asphalt-impregnated paper, 10 min rating, 3.5
lb/100 ft2
30 min rating, 4.1 lb/100 ft2
60 min rating, 5.7 lb/100 ft2
Bituminous paper (#15 felt), 10.6 lb/100 ft2
Polyamide film
Spun bonded polyolefin (SBPO), 1.3 lb/100 ft2
with crinkled surface, 1.4 lb/100 ft2
Wallpaper
paper, 3.1 to 3.4 lb/100 ft2
textile, 6.0 to 6.8 lb/100 ft2
vinyl, 3.5 lb/100 ft2
Other Construction Materials
Built-up roofing (hot-mopped)
Exterior insulated finish system (EIFS), 71 lb/
ft3
Glass fiber reinforced sheet, acrylic
Polyester
0.056
0.048
0.02-0.15
0.12
0.05
References/Comments
Burch and Desjarlais
(1995)
Burch and Desjarlais
(1995)
Kumaran (1996)
*
*
Kumaran (2002)
Burch and Desjarlais
(1995)
Burch and Desjarlais
(1995)
Kumaran (2002)
Dry cup*
Dry cup*
*Historical data, no reference available
**EIFS vapor permeance was tested with polymer cement base coat and latex acrylic finish coat of 0.17 in. thickness applied to expanded polystyrene of 1.3 in. thickness.
the surface film resistances between the assembly’s surfaces and the
interior and exterior environment (Ri and Ro). Table 10 gives typical
values for the surface film coefficients hi and ho and their reciprocals, the surface resistances Ri and Ro. As shown, the indoor values
depend on position of the surface, direction of heat transfer, and the
surface’s long-wave emissivity. Outdoors, the values depends on air
speed and the surface’s long-wave emissivity. Table 10 reflects
standard situations, with an assumed (approximate) interior surface
temperature representative of wall or roof assemblies. For situations that deviate substantially from standard conditions, including
interior surface temperatures for fenestration systems, use ASHRAE (1998) or values from Chapter 15 to determine the surface
film coefficients/resistances.
4.9
CODES AND STANDARDS
ASHRAE. 2010. Energy standard for buildings except low-rise residential
buildings. ANSI/ASHRAE/IES Standard 90.1-2010.
ASTM. 2010. Standard terminology relating to thermal insulation. Standard
C168-10. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2010. Standard test method for steady-state heat flux measurements
and thermal transmission properties by means of the guarded-hot-plate
apparatus. Standard C177-10. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2010. Standard test method for steady-state heat transfer properties
of pipe insulation. Standard C335/C335M-10e1. American Society for
Testing and Materials, West Conshohocken, PA.
26.20
2021 ASHRAE Handbook—Fundamentals
Table 7
Sorption/Desorption Isotherms of Building Materials at Various Relative Humidities
Sorption, % Moisture Content at
% Relative Humidity
Licensed for single user. © 2021 ASHRAE, Inc.
Material
Building Board and Siding
Cement board, 1/2 in.,
70 lb/ft3
Fiber cement board,
5/16 in., 86 lb/ft3
Gypsum wall board,
1/2 in., 39 lb/ft3
Hardboard siding,
7/16 in., 46 lb/ft3
Oriented strand board (OSB),
3/8 in., 41 lb/ft3
7/16 in., 41 lb/ft3
1/2 in., 41 lb/ft3
Particle board, 3/4 in.,
47 lb/ft3
Plywood, 1/2 in.
5/8 in.
3/4 in.
Plywood (exterior grade),
1/2 in., 36 lb/ft3
Wood fiber board,
7/16 in., 20 lb/ft3
1.0 in., 18.7 lb/ft3
Masonry Materials
Aerated concrete, 29 lb/ft3
37.5 lb/ft3
Cement mortar, 100 lb/ft3
Clay brick, 4 × 4 × 8 in.,
124 lb/ft3
Concrete, 138 lb/ft3
Lightweight concrete,
98 lb/ft3
Limestone, 156 lb/ft3
Perlite board
Portland stucco mix,
124 lb/ft3
Woods
Eastern white cedar, 1 in.,
22.5 lb/ft3
Eastern white pine, 1 in.,
28.7 lb/ft3
Southern yellow pine, 1 in.
31 lb/ft3
Spruce (transverse), 25 lb/ft3
Western red cedar, 1 in.,
21.8 lb/ft3
Insulation
Cellulose, dry blown,
1.87 lb/ft3
Glass fiber batt, 0.72 lb/ft3
Glass fiber board,
0.9 in., 7.5 lb/ft3
Glass fiber board facer,
0.06 in., 55 lb/ft3
Mineral fiber, 2.5 lb/ft3
Polystyrene, expanded,
0.92 lb/ft3
extruded,
1.79 lb/ft3
Polyurethane, sprayed foam,
2.43 lb/ft3
0.4 to 1/2 lb/ft3
Polyisocyanurate, 1.65 lb/ft3
Polyisocyanurate glass facer,
0.04 in., 26.8 lb/ft3
143
1.970
3.481
6.193
450.6
5.870.4 16.889.9 34.7100t
0.450.5 0.6570.5 1.890.8 4.294
42.7100t
Desorption, % Moisture Content at
% Relative Humidity
1.643
3.270
4.681
6.293
1899.27 2899.93
References
Kumaran (2002)
6.650.5 12.370.5 19.690.6 31.395.32 32.599.49 33.999.93 Kumaran (2002)
68.9100c 113100t
0.9950.4 1.3271.5 1.6984.8 1.8288.3
Kumaran (2002)
4.750.3 6.969.6 13.191.3 90100t
4.450.3 7.669.2 13.491.3 3891.3
Kumaran (2002)
4.648.9 7.669.1 14.788.6 126100c
6.949.9 9.169.4 16.290.3 17.392.3 39.399.3 60.699.8 Kumaran (2002)
5.448.9 8.269.1 14.788.6 160100t
7.949.9 9.969.4 17.490.3 39.199.3 62.799.8
Kumaran (2002)
4.648.9 7.869.1 14.888.6 124100t
7.949.9 1069.4 17.690.3 2092.3 4299.3 59.5
Kumaran (2002)
1.211.3 6.357.6 9.778.6 11.384.1 15.993.6 21.597.3 1.711.3 8.857.6 1478.6 16.684.1 1993.6 23.397.6 Kumaran (1996)
748.9
6.848.9
6.748.9
1.8311.3
9.269.1
9.669.1
10.169.1
6.958
15.888.6
16.888.6
17.688.6
9.578.7
170100t
140100t
190100t
12.184.5 17.993.8 22.1
4.650.6 7.470.5 15.891.1 304
8.449.9
8.649.9
8.949.9
2.0911.3
10.869.4
11.369.4
11.369.4
9.358
18.290.3
19.890.3
19.390.3
13.778.7
3.950.6 7.471.1 1590.6
1992.3
19.392.3
20.792.3
15.284.5
7099.3
4799.3
6699.3
19.893.8
101
79
9999.8
23.4
23099.71 23099.85 23099.93
0.6311.3 5.758
9.278.7 11.384.5 16.493.8 24.697.4 1.2611.3 7.658
1278.7
14.684.5 20.693.8 28.197.4
1.150.6
1.817.8
0.4249.9
0.0850
588.1
4.690.3
5.389.9
0.191.2
6.388.1
455.2
6.189.9
4.598.9
3497.81
6.675.6
1798.9
699.63
2.171.5
3.275.8
2.370.1
0.1269.1
83100c 172
6.492.4 9.695.9 17.598.4
26100t
9.9100t
1.150.6
2.317.8
3.449.9
050
2.271.5
2.833
4.470.2
091.2
7299.85
15.491.6
2299.63
8.299.71
9299.99
36.598
2599.93
9.199.93
Kumaran (2002)
Kumaran (2002)
Kumaran (2002)
Burch and
Desjarlais (1995)
Kumaran (2002)
Kumaran (2002)
Kumaran (1996)
Kumaran (2002)
Kumaran (2002)
0.8825.2 1.1544.9 1.7465 2.6280 3.3589.8 4.4598.2 0.9420 2.1945.4 2.9865.6 3.8584.8 4.5794.8
2.924.4 3.445.2 465.2
4.685 6.698
3.119.6 4.440 5.259.8 679.6
7.194.7
Kumaran (1996)
Kumaran (1996)
050
13033
350
Kumaran (2002)
Kumaran (1996)
Kumaran (2002)
070
0.188.5 1.8100t
16052 26075 38086 80097
3.770.3 5.889.9 12100t
070.5
0.188.6 0.2195.3 0.598.9 0.699.27 1.399.93
4.250
5.270.3 790.3
117099.8
10.395.29 11.698.9 11.799.93
3.449.8 7.670
12.888.5 228100t
1.750
7.470.5 11.988.7 8598.9
3.249.8 7.670
1288.5
192100t
3.250
970.5
12.488.7 8499.78
3.649.8 8.170
15.288.5 158100t
4.350
1070.5
15.688.7 5799.78
4.149.8 9.270
3.449.8 670
16.788.5 228100t
9.688.5 228100t
4.950
150
11.370.5 17.788.7 14895.96 18799.78
970.5
13.388.7 11399.78
550.2
1272.8
6.150.5 9.671.5 2488.1
11899.63 17699.92
2688
Kumaran (2002)
0.2150.6 0.3471.5 0.7588.1
0.2450.4 0.3571.4 0.6788.2
Kumaran (2002)
0.1611.3 0.75
0.8278.7 0.9684.5 1.393.8 2.0397.4 0.4311.3 0.8632.8 1.1158 1.2684.5 1.7493.8 2.1697.4 Burch and
Desjarlais (1995)
0.0911.3 0.5358 0.7678.7 0.8484.5 1.1493.8 1.5497.4 0.1811.3 0.5658 0.8778.7 1.0984.5 1.4593.8 1.8197.4 Burch and
Desjarlais (1995)
0.520.1 0.5545.4 0.5965 0.785.2 0.7694.5 0.897.5 0.520.1 0.5844.9 0.6364.9 0.8184.5 1.194.7 1.697.8 Kumaran (1996)
0.450.4 0.368.3 0.288.3
0.450.1 0.567.9 0.587.9
Kumaran (2002)
0.650.4 0.568.3 0.488.3
0.550.1 0.567.9 0.487.9
Kumaran (2002)
1.350.4 1.768.3 288.4
1.150.1 1.567.9 1.887.9
Kumaran (2002)
0.550.4 170.2
1.690.3
1.350.4 1.768.3 2.188.3
1.3611.3 4.558 6.878.7 984.5
150.5
2.170.9 791.3
1.150.1 1.567.9 1.987.9
0.8911.3 5.858 8.378.7 10.9
Kumaran (2002)
Kumaran (2002)
Burch and
Desjarlais (1995)
12.593.8 17.997.4
14.493.8 18.497.4
Licensed for single user. © 2021 ASHRAE, Inc.
Heat, Air, and Moisture Control in Building Assemblies—Material Properties
ASTM. 2010. Standard test method for steady-state thermal transmission
properties by means of the heat flow meter apparatus. Standard C518-10.
American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2015. Standard practice for selection of water vapor retarders for
thermal insulation. Standard C755-10 (R2015). American Society for
Testing and Materials, West Conshohocken, PA.
ASTM. 2005. Standard classification of potential health and safety concerns
associated with thermal insulation materials and accessories. Standard
C930-05. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2013. Standard practice for calculating thermal transmission properties under steady-state conditions. Standard C1045-07 (R2013). American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2011. Standard test method for thermal performance of building
materials and envelope assemblies by means of a hot box apparatus.
Standard C1363-11. American Society for Testing and Materials, West
Conshohocken, PA.
ASTM. 2016. Standard specification for insulated vinyl siding. Standard
D7793-16. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2010. Standard test methods for water vapor transmission of materials. Standard E96/E96M-10. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2009. Standard practices for air leakage site detection in building
envelopes and air barrier systems. Standard E1186-03 (2009). American
Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2011. Standard specification for air barrier (AB) material or system
for low-rise framed building walls. Standard E1677-11. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 2011. Standard test method for determining air leakage of air barrier
assemblies. Standard E2357-11. American Society for Testing and
Materials, West Conshohocken, PA.
CAN/ULC. 2003. Standard for determination of log-term thermal resistance
of closed-cell thermal insulating foams. CAN/ULC Standard S7702003. Standards Council of Canada, Ottawa, ON, and Underwriters Laboratories Canada, Toronto, ON.
VDI. 1999. Environmental meteorology—Interactions between atmosphere
and surfaces—Calculation of short-wave and long-wave radiation. Standard 3789 Part 2. Verein Deutscher Ingenieure (Association of German
Engineers), Dusseldorf.
REFERENCES
ASHRAE members can access ASHRAE Journal articles and
ASHRAE research project final reports at technologyportal.ashrae
.org. Articles and reports are also available for purchase by nonmembers in the online ASHRAE Bookstore at www.ashrae.org/bookstore.
Adams, L. 1971. Supporting cryogenic equipment with wood. Chemical Engineering (May):156-158.
ASHRAE. 1998. Standard method for determining and expressing the heat
transfer and total optical properties of fenestration products. SPC 142.
ASTM. 1985a. Guarded hot plate and heat flow meter methodology. Special
Technical Publication STP 879. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 1985b. Building applications of heat flux transducers. Special Technical Publication STP 885. American Society for Testing and Materials,
West Conshohocken, PA.
ASTM. 1988. Thermal insulation: Material and systems. Special Technical
Publication STP 922. American Society for Testing and Materials, West
Conshohocken, PA.
ASTM. 1990. Insulation materials: Testing and applications. Special Technical Publication STP 1030. American Society for Testing and Materials, West Conshohocken, PA.
ASTM. 1991. Insulation materials: Testing and applications, 2nd vol. Special Technical Publication STP 1116. American Society for Testing and
Materials, West Conshohocken, PA.
ASTM. Annual. Annual book of ASTM standards, vol. 04.06, Thermal insulation; building and environmental acoustics. American Society for Testing and Materials, West Conshohocken, PA.
Bassett, M.R., and H.A. Trethowen. 1984. Effect of condensation on emittance of reflective insulation. Journal of Thermal Insulation 8(October):127.
Binder, A., D. Zirkelbach, and H.M. Künzel. 2010. Test method to quantify
the wicking properties of insulation materials designed to prevent interstitial condensation. Proceedings of Buildings XI Conference, ASHRAE.
Bomberg, M.T., and M.K. Kumaran. 1986. A test method to determine air
flow resistance of exterior membranes and sheathings. Journal of Thermal Insulation 9:224-235.
Brandreth, D.A., ed. 1986. Advances in foam aging—A topic in energy conservation series. Caissa Editions, Yorklyn, DE.
Table 10
Table 8
Normal Range
4.2 to 17.4
6 to 17.4
6 to 11.4
6 to 17.4
Lowb
5.4
11.4
7.8
6.6
Highc
15.6
15.6
10.8
15.6
a Reasonable
values for use when no site- or soil-specific data are available.
conservative values for minimum heat loss through soil (e.g., use in soil
heat exchanger or earth-contact cooling calculations). Values are from Salomone and
Marlowe (1989).
c Moderately conservative values for maximum heat loss through soil (e.g., use in peak
winter heat loss calculations). Values are from Salomone and Marlowe (1989).
b Moderately
Table 9
Surface Film Coefficients/Resistances
Typical Apparent Thermal Conductivity Values
for Soils, Btu· in/h·ft2 ·°F
Surface Emittance, 
Recommended Values for Designa
Sands
Silts
Clays
Loams
26.21
Typical Apparent Thermal Conductivity Values
for Rocks, Btu· in/h·ft2 · °F
Normal Range
Pumice, tuff, obsidian
Basalt
Shale
Granite
Limestone, dolomite, marble
Quartzose sandstone
3.6 to 15.6
3.6 to 18.0
6 to 27.6
12 to 30
8.4 to 30
9.6 to 54
Position of
Surface
Direction
of
Heat Flow
Indoor
Horizontal
Sloping at 45°
Vertical
Sloping at 45°
Horizontal
Upward
Upward
Horizontal
Downward
Downward
Reflective
 = 0.20
 = 0.05
hi
Ri
hi
Ri
hi
Ri
1.63
1.60
1.46
1.32
1.08
0.61
0.62
0.68
0.76
0.92
0.91
0.88
0.74
0.60
0.37
1.10
1.14
1.35
1.67
2.70
0.76
0.73
0.59
0.45
0.22
1.32
1.37
1.70
2.22
4.55
ho
Ro
Any
6.00
0.17
—
—
—
—
Any
4.00
0.25
—
—
—
—
Outdoor (any position)
15 mph wind
(for winter)
7.5 mph wind
(for summer)
Nonreflective
 = 0.90
Notes:
1. Surface conductance hi and ho measured in Btu/h·ft2 ·°F; resistance Ri and Ro in
h·ft2 ·°F/Btu.
2. No surface has both an air space resistance value and a surface resistance value.
3. Conductances are for surfaces of the stated emittance facing virtual blackbody surroundings at same temperature as ambient air. Values based on surface/air temperature difference of 10°F and surface temperatures of 70°F.
4. See Chapter 4 for more detailed information.
5. Condensate can have significant effect on surface emittance (see Table 2). Also, oxidation, corrosion, and accumulation of dust and dirt can dramatically increase surface emittance. Emittance values of 0.05 should only be used where highly reflective
surface can be maintained over the service life of the assembly.