Wood
Content
Introduction
Scott Leavengood
Wood Products Extension Agent
Wood.xls is the revised and improved version of the Dimensional Change software program published by the
Oregon State University Extension Service in 1997. The Dimensional Change program is a DOS-based
program for calculating magnitude of shrink and swell for wood species given change in moisture content and/
or ambient temperature and relative humidity. Wood.xls improves upon the Dimensional Change program by
providing a more user-friendly interface via Microsoft Excel, allows the user to select from 103 North
American wood species (as opposed to 60 for the Dimensional Change program), enables quick comparisons
of 3 species at a time, and allows the user to easily add up to 10 new species. Wood.xls also includes a
worksheet for calculating density given specific gravity.
Note: The dimensional change values calculated by Wood.xls are estimates. As stated in the Wood Handbook (1999,
Forest Products Society, Madison, WI), with respect to the equation used to estimate dimensional change, "...the equation
assumes that the shrinkage-moisture content relationship is linear. ...this is not the case, so some error is introduced."
Also, because commercial lumber is often not perfectly flatsawn or quartersawn, the equations will probably overestimate
width shrinkage and underestimate thickness shrinkage.
Many of us have experienced dresser drawers that stick during certain times of the year, whereas
the same drawers slide smoothly at other times of the year. Furniture makers and other
woodworkers find that a sufficiently tight joint made using wood that is "too wet" results in an open
and unsightly joint after the wood dries. Even simply moving wood products from one location to
another can cause problems. For example, face veneers on plywood made in the dry climate of
eastern Oregon may swell and buckle when they reach the more hot and humid climate of the U.S.
Southeast. All of these problems are symptoms of wood's love for moisture. See OSU Extension
publication EM8600- Wood and Moisture Relationships for more information on wood and water.
Lumber sawn fresh from a log is known as "green" and is usually saturated with moisture from the
living tree. Green lumber loses moisture until it comes into equilibrium with its surroundings. In
addition to the moisture loss from the green state, wood also undergoes constant changes in
moisture content while in service as a result of fluctuations in temperature and relative humidity.
When wood gains moisture it swells and when wood loses moisture it shrinks. The problem for the
woodworker is knowing how much a certain piece will shrink or swell based on wood species,
environmental conditions, grain orientation (see Figure 1), and piece size.
flatsawn, plainsawn
quartersawn, edge-grained,
bastard sawn
vertical grain (VG)
Figure 1. Grain orientation
Wood.xls uses published formulas (see Formulas worksheet) and dimensional change coefficients
to calculate the thickness and width change of wood based on changes in moisture content. The
user selects:
species (choice of one of 42 North American softwoods, and 61 North American hardwoods)
moisture conditions (initial and final moisture content, if known, or ambient temperature and relative humidity)
board or veneer width and thickness
grain orientation - flatsawn (works also for rotary peeled or plain-sliced), quartersawn (or quartersliced), or mixed grain.
The program calculates the dimensional change and the final board size (based on the size of the
board the user entered).
In addition to the Dimensional Change worksheet, Wood.xls has 2 other functional worksheets EMC (equilibrium moisture content) and SG & Density (specific gravity and density).
EMC calculates the equilibrium moisture content for wood given the ambient temperature and
relative humidity. This worksheet is used by the Dimensional Change worksheet to estimate initial
and/or final moisture content conditions. This worksheet also has a function to calculate moisture
content given green weight and ovendry weight.
SG & Density calculates specific gravity (SG) at user-defined moisture contents given SG green
and volumetric shrinkage. The user may select a species from the drop-down lists or enter values
in the spaces provided. The program calculates density, ovendry density of the wood, weight per
board foot at 15 percent moisture content and the weight of the water in the wood at the specified
moisture content. The terms density and SG are often used interchangeably, however these terms
have different meanings. Density is the weight per unit volume (e.g., lbs/ft 3 or kg/m3) whereas SG is
the ratio of the density of a material to the density of water and is unitless. Wood is unique in that
its weight and volume change as it gains and loses moisture. Therefore, its SG also changes. This
issue is often confusing for people wanting to estimate weight given SG. This worksheet helps to
simplify the process of estimating weight of wood at varying moisture contents. For more
information on specific gravity and other topics in wood technology, please see:
The Nature of Wood and Wood Products CD-ROM
1998. Regents of the University of Minnesota. Available from the Forest Products Society,
Madison, WI. (608) 231-2152.
How to Use Wood.xls
An Example
Consider the following example:
Let's say you plan to panel a 20 foot wide interior wall of your home with flatsawn 1x6 (actual size
3/4 inches x 5½ inches) tongue-and-groove paneling. The local home center has incense-cedar,
redwood (young-growth), and ponderosa pine, all at 19 percent moisture content. You plan to
purchase the wood and install it immediately. Let's say the temperature inside is kept relatively
constant at 72° F and the relative humidity is approximately 45 percent.
What will happen to the wood? Will it shrink, swell, or stay the same size? If it changes in size,
approximately how much will it change? Will all the species shrink or swell by the same amount?
To complete this sample exercise, start Microsoft Excel and open Wood.xls. Click on the
Dimensional Change worksheet tab.
Click on the species selection box and choose cedar, incense- for species 1, redwood, younggrowth for species 2, and pine, ponderosa for species 3.
For the initial conditions, enter 19 in the MC (%) column. Note: If only the initial temperature and
humidity conditions are known, you would enter those values instead and leave the MC (%) column
blank.
For the final conditions, enter 72 in the Temp column and 45 in the RH (%) column. For this
example, we will leave the MC (%) column blank as the final moisture content is not known. The
program will estimate final moisture content for you given ambient temperature and humidity.
The program calculates the change in moisture content and reports this value in the Change in MC
column. For this example, the change in MC is 10.565 percent.
Enter the thickness and width in the appropriate column. For this example, enter 0.75 for thickness
and 5.5 for width for all 3 species.
In the Grain Orientation column, select flatsawn for all 3 species.
The program calculates the approximate dimensional change in thickness and width and reports the
estimated final piece size. The values reported are:
Approximate
Dimensional Change in
Species
Thickness
Width
cedar, incense0.009 in
0.103 in
redwood, young-growth 0.006 in
0.097 in
pine, ponderosa
0.010 in
0.123 in
Final Size
0.741 by 5.397
0.744 by 5.403
0.740 by 5.377
Therefore, ponderosa pine will shrink the most in width at 0.123 inches or a little under 1/8 inches.
This shrinkage is due solely to moving the lumber, initially at 19 percent MC, to drier conditions
indoors. For this example, paneling a 20 ft. (240 inches) wide wall with 5½-inch material will
require:
240 ÷ 5½ = approx. 44 pieces
To calculate total shrinkage across the width of the wall, multiply the number of pieces by the
shrinkage per piece. Therefore, total shrinkage for 44 pieces will be:
44 x 0.123 = approx. 5½ inches
Across the width of a 20 ft. wide wall, the paneling will shrink nearly 5½ inches. Remember, these
numbers are estimates.
Does this mean you'll have a 5½-inch gap at one end of the wall? Because of the way the paneling
is installed (glued and/or nailed to the wall), its shrinkage in width will be restrained. What this
number tells you is how much the paneling might move if it were unrestrained, and therefore you
have a relative idea of how much stress is in the boards as their movement is restrained. The more
likely occurrence in this example will be splitting around nail holes, buckling of individual pieces, or
the opening of gaps between adjacent boards.
To get an idea of the magnitude of difference between wood species, try running the program again
except this time choose a dense hardwood like hickory or Pacific madrone.
Instructions for "wood.xls"
Scott Leavengood
Wood Products Extension Agent
This program contains 3 functional worksheets:
1. Dimensional Change
Calculates dimensional change for wood based on species, initial and final moisture content (or
temperature and relative humidity), grain orientation, and piece size (width and thickness).
a. Select species from list (user may choose up to 3 species)
b. Enter initial moisture content [MC (%)] or temperature and relative humidity [RH (%)]
MC and RH must be in percent (for example, 80 not 0.80)
[NOTE: equilibrium moisture content (EMC) is only calculated if MC is left blank]
c. Enter final moisture content [MC (%)] or temperature and relative humidity [RH (%)]
[NOTE: equilibrium moisture content (EMC) is only calculated if MC is left blank]
d. Enter thickness and width (inches or millimeters)
e. Select grain orientation
Options:
The user may add up to 10 new species. The dimensional change coefficients, percent shrinkage values,
and specific gravity values may be found in textbooks, wood software (for example, Woods of the World
CD-ROM) or other such sources. To add a species, click on the tab for the %Shrinkage & SG worksheet.
Scroll down the list to find the entry in column B, "new species1." Move the cursor to cell B113 and type
the new name. Press the arrow right key on the keyboard and enter the percentage shrinkage from green
to ovendry in the radial direction (cell C113). Arrow right and enter percent shrinkage in the tangential
direction (cell D113). Arrow right and enter the coefficient of dimensional change in the radial direction
(cell E113). Arrow right and enter the coefficient of dimensional change in the tangential direction (cell
F113). Arrow right and enter the percent volumetric shrinkage from green to ovendry (cell G113).
Cells H113 and I113 are for reference only and may be left blank (the values are not used by the
program). Arrow right to cell J113 and enter the specific gravity green. Arrow right to cell K113 and enter
the specific gravity at 12% moisture content.
To add the next species, follow the same steps beginning in cell B114 for "new species 2."
To add more than 10 new species, the user may contact the author for assistance at (503) 725-2123 or
by sending e-mail to [email protected].
2. EMC
Calculates equilibrium moisture content (EMC) given temperature and relative humidity.
a. Enter temperature in either Fahrenheit or Celsius. If in Celsius, check the box above "Temp."
b. Enter relative humidity [RH (%)] in percent
This worksheet also calculates moisture content given green weight and ovendry weight.
3. SG & Density
The program calculates specific gravity (SG) at user-selected moisture content, density, ovendry density,
density due to water, and weight per board foot at 15% MC. The user may either select the species of
interest from the drop-down boxes, or enter the values in the spaces provided.
Table 1. Green specific gravity known
a. Select species or enter green specific gravity (SGGRN)
b. Select species or enter percent volumetric shrinkage
c. Enter moisture content (MC) of interest.
d. Select nominal board dimensions to calculate weight of 1 board foot (BF) at 15% MC
Table 2. Dry specific gravity known
a. Select species or enter dry specific gravity (SG12)
b. Select species or enter percent volumetric shrinkage
c. Select nominal board dimensions to calculate weight of 1 board foot (BF) at 15% MC
The worksheets cuft per BF, %Shrinkage & SG, and Formulas are used by the program and are
available to the user as a reference.
71
83
75
1
0
3.8
flatsawn
quartersawn
Dimensional Change in Wood
INITIAL CONDITIONS
FINAL CONDITIONS
Celsius
Species
1 Douglas-fir, interior north
MC (%)
Temp
RH (%)
mixed grain
Celsius
MC (%)
RH (%)
in MC
72
45
10.565
EMC = 8.44%
2 larch, western
3 fir, grand
1
6.9
4.5
Approximate
Change
Temp
19
1
EMC = Equilibrium Moisture Content
shrink
Metric (mm)
Thickness
Width
Grain
Orientation
Dimensional Change in
Thickness
Width
Final Size
0.75
5.5
flatsawn
0.01 in
0.137 in
0.74 by 5.363
0.75
5.5
flatsawn
0.012 in
0.182 in
0.738 by 5.318
0.75
5.5
flatsawn
0.009 in
0.149 in
0.741 by 5.351
0
Note: See %Shrinkage & SG worksheet for definitions of Douglas-fir ranges
Note: Flatsawn includes plainsawn, rotary peeled, or plain-sliced.
Quartersawn includes edge-grained, vertical grained, or quarter-sliced
Mixed grain includes bastard sawn lumber. The calculated
shrink/ swell is the average of quartersawn and flatsawn.
flatsawn, plainsawn
quartersawn, edge-grained
vertical-grained (VG)
bastard sawn
Equilibrium Moisture Content (EMC)
Enter temperature and relative humidity to
calculate equilibrium moisture content (EMC)
Celsius
Temp
72
#N/A
72
RH (%)
EMC
45
8.44
#N/A
#N/A
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45
#N/A
8.44
Wood Moisture Content =
Green weight 210.38
Ovendry weight 110.67
W
K
384.05760 0.81996
K1
K2
90.1%
Enter green weight and ovendry weight
to calculate moisture content
KH
K1KH K1K2K2H2
5.91110
2.66617
0.36898
2.18109
2.14569
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384.05760 0.81996
5.91110
2.66617
0.36898
2.18109
2.14569
ovendry weight
re content
0
Converted temp
72
#N/A
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0
#N/A
72
Specific Gravity & Density
Table 1. Green Specific Gravity (SGGRN) Known
###
% Vol.
Shrinkage
SGGRN
GRN to OD
82
juniper,
0.41 western
7.95
83
larch,
larch,
western 14
0.48western
MC (%)
118.6
100
SGMC
Metric
Density
0.41 @ 118.6% MC
0.48 @ 100% MC
#N/A @ 0% MC
#N/A @ 0% MC
% Vol.
56 lbs/ft3 @ 118.6% MC
59.9 lbs/ft3 @ 100% MC
#N/A @ 0% MC
#N/A @ 0% MC
0
Density
Density due to Water
1.76 lbs
27.81 lbs/ft3
33 lbs/ft3 @118.6% MC
2.15 lbs
#N/A
#N/A
34.84 lbs/ft3
#N/A lbs/ft3
#N/A lbs/ft3
34.8 lbs/ft3 @100% MC
#N/A
#N/A
Surfaced Dry (15% MC)
26
Weight per board foot of
Shrinkage
GRN to OD
?
Ovendry
1x6, 4/4x6
Table 2. Dry Specific Gravity (SG12) Known
SG12
2
Weight per board foot of
Density
Metric
?
Ovendry
2x4
Surfaced Dry (15% MC)
Density
Density due to Water
97
pine,
0.45radiata (Monterey)
10.4
31.5 lbs/ft3 @ 12% MC
1.75 lbs
29.3 lbs/ft3
3.5 lbs/ft3 @12% MC
70
Douglas-fir,
coast
0.48
12.4
33.6 lbs/ft3 @ 12% MC
0 lbs/ft3 @ 12% MC
0 lbs/ft3 @ 12% MC
1.87 lbs
#N/A
#N/A
31.5 lbs/ft3
#N/A
#N/A
3.8 lbs/ft3 @12% MC
#N/A
#N/A
Actual
Nominal
Width
Thickness
Width
Thickness
0.75
0.75
0.75
0.75
0.75
1.15625
1.15625
1.15625
1.15625
1.15625
1.40625
1.40625
1.40625
1.40625
1.40625
1.59375
1.59375
1.59375
1.59375
1.59375
1.8125
1.8125
1.8125
1.8125
1.8125
1.5
1.5
1.5
1.5
1.5
3.5
3.5
3.5
3.5
3.5
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
1
1
1
1
1
1.25
1.25
1.25
1.25
1.25
1.5
1.5
1.5
1.5
1.5
1.75
1.75
1.75
1.75
1.75
2
2
2
2
2
2
2
2
2
2
4
4
4
4
4
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
Nominal
Dim.
Surfaced Dry
1x4, 4/4x4
1x6, 4/4x6
1x8, 4/4x8
1x10, 4/4x10
1x12, 4/4x12
5/4x4
5/4x6
5/4x8
5/4x10
5/4x12
6/4x4
6/4x6
6/4x8
6/4x10
6/4x12
7/4x4
7/4x6
7/4x8
7/4x10
7/4x12
8/4x4
8/4x6
8/4x8
8/4x10
8/4x12
2x4
2x6
2x8
2x10
2x12
4x4
4x6
4x8
4x10
4x12
0.0546875
0.05729167
0.05664063
0.0578125
0.05859375
0.06744792
0.07065972
0.06985677
0.07130208
0.07226563
0.06835938
0.07161458
0.07080078
0.07226563
0.07324219
0.06640625
0.06956845
0.0687779
0.07020089
0.07114955
0.06608073
0.06922743
0.06844076
0.06985677
0.07080078
0.0546875
0.05729167
0.05664063
0.0578125
0.05859375
0.06380208
0.06684028
0.06608073
0.06744792
0.06835938
ft3/BF
1
0
2 0.057292
3
0
4
0
5
0
6
0
7
0
8
0
9
0
10
0
11
0
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
24
0
25
0
26
0
27
0
28
0
29
0
30
0
31
0
32
0
33
0
34
0
35
0
0.057292
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.054688
0
0
0
0
0
0
0
0
0
0.054688
Table values from the Wood Handbook: Wood as an Engineering Material. 1999.
Forest Products Society, Madison, WI,
Alden, H.A. Hardwoods of North America. 1995. General Technical Report FPL-GTR-83.
USDA Forest Service, Forest Products Laboratory, Madison, WI, and
Kininmonth, J.A. and L.J. Whitehouse. Properties and Uses of New Zealand Radiata Pine. 1991. Forest Research Institute, Rotorua, NZ.
Changes > 6-14%
Changes within 6-14%
% Vol.
Average
% Shrinkage grn to OD
Dim. Change Coeff.
Shrinkage
Green MC (%)
Radial
Tangential
Radial
Tangential
GRN to OD
Heartwood
Sapwood
SGGRN
SG12
60 walnut, black
4.4
5
4.6
4.1
3.7
4.9
3.5
6.6
5.5
6.3
4.7
6.5
7.3
3.6
3.4
3.7
3.4
3.6
3.9
4.2
4.7
4.8
4.9
5.3
4.8
4.9
7.7
7.2
7
7.6
4.8
4.2
4.6
5.6
5.2
5.4
4.7
3.7
4.8
4
3
4.8
4.4
4
4
4.7
4.4
5
6.6
5.3
5.6
7.9
4.6
4
5.3
5
4.9
5.1
4.2
5.5
7.3
7.8
7.1
8.1
6.3
7.8
6.7
9.3
11.9
8.6
9.2
9
9.5
8.1
6.4
7.1
6.7
8.6
9.2
9.5
10.2
8.1
8.9
11.6
8.9
8.9
11
11.5
10.5
12.6
9.9
6.6
7.2
12.4
8.8
6.6
8.3
7.1
9.3
8.2
7.2
9.9
11.1
9.9
8.6
11.3
9.8
9.6
9.5
12.7
10.5
11.2
8.2
6.2
10.2
8.4
11.7
8.7
7.6
7.8
0.00151
0.00172
0.00169
0.00141
0.00126
0.00169
0.00119
0.0023
0.0019
0.00219
0.00162
0.00256
0.00256
0.00123
0.00116
0.00126
0.00116
0.00123
0.00133
0.00144
0.00183
0.00165
0.00169
0.00183
0.00165
0.00169
0.00259
0.00259
0.00259
0.00259
0.00165
0.00144
0.00158
0.00194
0.0018
0.00187
0.00162
0.00126
0.00165
0.00137
0.00102
0.00165
0.00123
0.00151
0.00158
0.00158
0.00151
0.00151
0.0023
0.00183
0.0018
0.00278
0.00158
0.00137
0.00183
0.00172
0.00169
0.00176
0.00144
0.0019
0.00256
0.00274
0.00274
0.00285
0.00219
0.00274
0.00234
0.0033
0.00431
0.00304
0.00327
0.00338
0.00338
0.00285
0.00223
0.00248
0.00234
0.00304
0.00327
0.00338
0.00419
0.00285
0.00315
0.00419
0.00315
0.00315
0.00411
0.00411
0.00411
0.00411
0.00353
0.0023
0.00252
0.00451
0.00312
0.0023
0.00293
0.00248
0.00353
0.00289
0.00252
0.00353
0.0023
0.0035
0.00369
0.00369
0.0035
0.0035
0.00338
0.00462
0.00365
0.00403
0.00289
0.00216
0.00365
0.00296
0.00423
0.00308
0.00267
0.00274
12.6
15.2
12.5
13.2
12
13.3
11.5
15.8
17.2
16.2
13.5
15.6
16.8
12.5
10.6
11.5
11.6
12.4
13.9
14.6
15.4
14.9
13.8
17.7
13.8
13.6
17.8
17.9
16.7
19.2
16.9
10.8
10.2
18.1
13.6
12.3
12.9
11.6
14
12.6
12
14.7
15.1
19
13.7
16.1
16.1
18.9
14.7
16
16.3
19.1
12.7
10.3
15.8
14.1
17.3
14.4
12.5
12.8
?
95
?
?
?
46
95
81
55
89
?
75
74
?
?
58
120
162
?
95
66
44
?
?
61
?
70
71
?
?
?
?
?
?
?
?
?
?
?
?
58
65
76
?
80
83
81
82
?
?
64
?
83
?
79
114
?
87
150
90
97
?
58
?
?
44
113
133
72
72
?
70
72
?
?
?
?
146
?
92
61
57
?
?
65
?
52
49
?
?
?
?
?
?
?
?
?
?
?
?
97
72
75
?
69
75
81
74
?
?
78
?
106
?
137
130
?
115
116
73
0.37
0.45
0.53
0.5
0.48
0.55
0.35
0.32
0.56
0.48
0.49
0.6
0.55
0.33
0.36
0.47
0.4
0.31
0.37
0.46
0.59
0.57
0.48
0.6
0.49
0.6
0.64
0.66
0.64
0.62
0.5
0.6
0.66
0.58
0.44
0.46
0.42
0.44
0.52
0.49
0.44
0.56
0.56
0.56
0.56
0.52
0.56
0.56
0.8
0.57
0.6
0.64
0.4
0.42
0.46
0.46
0.58
0.46
0.46
0.51
0.41
0.49
0.56
0.55
0.52
0.6
0.38
0.37
0.64
0.55
?
0.65
0.62
0.36
0.38
0.5
0.43
0.35
0.4
0.5
0.64
0.63
0.53
0.66
0.53
0.66
0.72
0.75
0.72
0.69
0.57
?
0.69
0.65
0.48
0.5
?
0.48
0.57
0.54
0.47
0.63
0.61
0.63
0.63
0.59
0.63
0.69
0.88
0.63
0.68
0.74
0.42
0.46
0.52
0.49
?
0.5
0.5
0.55
61 willow, black
3.3
8.7
0.00112
0.00308
13.9
?
?
0.36
0.39
SPECIES
1 alder, red
2 ash, black
3 ash, green
4 ash, Oregon
5 ash, pumpkin
6 ash, white
7 aspen, quaking
8 basswood, American
9 beech, American
10 birch, paper
11 birch, river
12 birch, sweet
13 birch, yellow
14 buckeye, yellow
15 butternut
16 cherry, black
17 chestnut, American
18 cottonwood, black
19 cottonwood, eastern
20 elm, American
21 elm, cedar
22 elm, rock
23 elm, slippery
24 elm, winged
25 hackberry
26 hickory, pecan
27 hickory, mockernut
28 hickory, pignut
29 hickory, shagbark
30 hickory, shellbark
31 holly, American
32 honeylocust
33 locust, black
34 madrone, Pacific
35 magnolia, cucumbertree
36 magnolia, Southern
37 magnolia, sweetbay
38 maple, bigleaf
39 maple, black
40 maple, red
41 maple, silver
42 maple, sugar
43 oak, black
44 oak, laurel
45 oak, Northern red
46 oak, Southern red
47 oak, water
48 oak, willow
49 oak, live
50 oak, overcup
51 oak, white
52 persimmon, common
53 poplar-yellow
54 sassafras
55 sweetgum
56 sycamore, American
57 tanoak
58 tupelo, black
59 tupelo, water
62 baldcypress
63 cedar, Alaska64 cedar, Atlantic white65 cedar, eastern redcedar
66 cedar, incense67 cedar, Northern white68 cedar, Port-Orford69 cedar, western redcedar
70 Douglas-fir, coast
71 Douglas-fir, interior north
72 Douglas-fir, interior west
73 fir, balsam
74 fir, California red
75 fir, grand
76 fir, noble
77 fir, Pacific silver
78 fir, subalpine
79 fir, white
80 hemlock, eastern
81 hemlock, western
82 juniper, western
83 larch, western
84 pine, eastern white
85 pine, jack
86 pine, loblolly
87 pine, lodgepole
88 pine, longleaf
89 pine, pond
90 pine, ponderosa
91 pine, red
92 pine, shortleaf
93 pine, slash
94 pine, sugar
95 pine, Virginia
96 pine, western white
97 pine, radiata (Monterey)
98 redwood, old-growth
99 redwood, young-growth
100 spruce, black
101 spruce, Engelmann
102 spruce, red
103 spruce, Sitka
104 tamarack
105 new species1
106 new species2
107 new species3
108 new species4
109 new species5
110 new species6
111 new species7
112 new species8
113 new species9
114 new species10
3.8
2.8
2.9
3.1
3.3
2.2
4.6
2.4
4.8
3.8
4.8
2.9
4.5
3.4
4.3
4.4
2.6
3.3
3
4.2
3.3
4.5
2.1
3.7
4.8
4.3
5.1
5.1
3.9
3.8
4.6
5.4
2.9
4.2
4.1
3.4
2.6
2.2
4.1
3.8
3.8
4.3
3.7
6.2
6
5.4
4.7
5.2
4.9
6.9
5
7.6
6.9
7.5
6.9
7.9
7.5
8.3
9.2
7.4
7
6.8
7.8
4.7
9.1
6.1
6.6
7.4
6.7
7.5
7.1
6.2
7.2
7.7
7.6
5.6
7.2
7.4
7
4.4
4.9
6.8
7.1
7.8
7.5
7.4
0.0013
0.00095
0.00099
0.00106
0.00112
0.00101
0.00158
0.00111
0.00165
0.0013
0.00165
0.00099
0.00155
0.00112
0.00148
0.00151
0.00088
0.00112
0.00102
0.00144
0.00111
0.00155
0.00071
0.00126
0.00165
0.00148
0.00176
0.00165
0.00133
0.0013
0.00158
0.00187
0.00099
0.00144
0.00141
0.001
0.0012
0.00101
0.00141
0.0013
0.0013
0.00148
0.00126
0.00216
0.00208
0.00187
0.00162
0.0018
0.00229
0.00241
0.00234
0.00267
0.00241
0.00263
0.00241
0.00278
0.00245
0.00293
0.00327
0.00259
0.00245
0.00237
0.00274
0.00155
0.00323
0.00212
0.0023
0.00259
0.00234
0.00263
0.00259
0.00216
0.00252
0.00271
0.00267
0.00194
0.00252
0.00259
0.00233
0.00205
0.00229
0.00237
0.00248
0.00274
0.00263
0.00259
10.5
9.2
8.8
7.8
7.7
7.2
10.1
6.8
12.4
10.7
11.8
11.2
11.4
11
12.4
13
9.4
9.8
9.7
12.4
7.95
14
8.2
10.3
12.3
11.1
12.2
11.2
9.7
11.3
12.3
12.1
7.9
11.9
11.8
10.4
6.8
7
11.3
11
11.8
11.5
13.6
121
32
?
33
40
?
50
58
37
?
?
?
?
91
34
55
?
98
97
85
?
54
?
?
33
41
31
?
40
32
32
?
98
?
62
45
86
?
?
51
?
41
49
171
166
?
?
213
?
98
249
115
?
?
?
?
136
115
164
?
160
119
170
?
110
?
?
110
120
106
?
148
134
122
?
219
?
148
120-180
210
?
?
173
?
142
?
0.42
0.42
0.31
0.44
0.35
0.29
0.39
0.31
0.45
0.45
0.46
0.33
0.36
0.35
0.37
0.4
0.31
0.37
0.38
0.42
0.41
0.48
0.34
0.4
0.47
0.38
0.54
0.51
0.38
0.41
0.47
0.54
0.34
0.45
0.35
?
0.38
0.34
0.38
0.33
0.37
0.37
0.49
0.46
0.44
0.32
0.47
0.37
0.31
0.43
0.32
0.48
0.48
0.5
0.35
0.38
0.37
0.39
0.43
0.32
0.39
0.4
0.45
0.44
0.52
0.35
0.43
0.51
0.41
0.59
0.56
0.4
0.46
0.51
0.59
0.36
0.48
0.38
0.45
0.4
0.35
0.42
0.35
0.4
0.4
0.53
Formulas from the Wood Handbook: Wood as an Engineering Material. 1999. Forest Products Society,
and
Madison, WI
Haygreen, J.G. and Bowyer, J.L. 1989. Forest Products and Wood Science: An Introduction -
Second Edition. 1989. University of Iowa Press, Ames, IA.
Dimensional Change
The change in dimension within the moisture content limits of 6 to 14 percent is
calculated as:
Change in dimension = DI [CT(MF - MI)]
where:
DI = initial dimension (in inches or other units)
CT = dimensional change coefficient, tangential direction (for radial direction use C R)
MF = final moisture content (percent)
MI = initial moisture content (percent)
Approximate dimensional changes associated with moisture content changes larger than
6 to 14 percent, or when one value is outside of those limits, can be calculated by:
DI(MF - MI)
Change in dimension =
30(100)
ST
where:
- 30 + MI
DI = initial dimension (in inches or other units)
ST = tangential shrinkage (percent) from green to ovendry (for radial direction use S R)
MF = final moisture content (percent)
MI = initial moisture content (percent)
Note: Neither MI nor MF should exceed 30, the assumed moisture content when shrinkage
starts for most species.
Equilibrium Moisture Content (EMC)
EMC =
where:
1800
W
KH + (K1KH + 2K1K2K2H2)
1-KH
(1 + K1KH + K1K2K2H2)
W = 330 + 0.452T + 0.00415T 2
K = 0.791 + 0.000463T - 0.000000844T 2
H = relative humidity (%)
K1 = 6.34 + 0.000775T - 0.0000935T 2
K2 = 1.09 + 0.0284T - 0.0000904T 2
T = temperature (°F)
SG & Density
Specific Gravity (SG) =
where:
ODW
Weight of equal volume of water
ODW = ovendry weight of wood
SGX% MC =
SGGRN
1 - [(% vol. shrinkage green to OD)*(30 - MC)]
100
30
where:
SGGRN = green specific gravity
OD = ovendry
MC = moisture content (percent)
DensityX% MC =
where:
(SGX% MC)*(density of water)*(1+ MC/100)
density of water = 62.4 lbs/ft3
MC = moisture content (%)
Weight per board foot (BF) for S-DRY (surfaced dry, 15% MC) lumber is calculated as:
Weight/BFS-DRY = (Density15%MC)*(actual ft3/nominal BF)
where:
Density15%MC = density in lbs/ft3 at 15% moisture content
Actual ft3/nominal BF = actual cubic feet per nominal board foot, calculated as:
(actual thickness inches* actual width inches * 1ft length)/144
(nominal width * nominal thickness* 1ft length)/12
Scott Leavengood
Wood Products Extension Agent
Wood.xls is the revised and improved version of the Dimensional Change software program published by the
Oregon State University Extension Service in 1997. The Dimensional Change program is a DOS-based
program for calculating magnitude of shrink and swell for wood species given change in moisture content and/
or ambient temperature and relative humidity. Wood.xls improves upon the Dimensional Change program by
providing a more user-friendly interface via Microsoft Excel, allows the user to select from 103 North
American wood species (as opposed to 60 for the Dimensional Change program), enables quick comparisons
of 3 species at a time, and allows the user to easily add up to 10 new species. Wood.xls also includes a
worksheet for calculating density given specific gravity.
Note: The dimensional change values calculated by Wood.xls are estimates. As stated in the Wood Handbook (1999,
Forest Products Society, Madison, WI), with respect to the equation used to estimate dimensional change, "...the equation
assumes that the shrinkage-moisture content relationship is linear. ...this is not the case, so some error is introduced."
Also, because commercial lumber is often not perfectly flatsawn or quartersawn, the equations will probably overestimate
width shrinkage and underestimate thickness shrinkage.
Many of us have experienced dresser drawers that stick during certain times of the year, whereas
the same drawers slide smoothly at other times of the year. Furniture makers and other
woodworkers find that a sufficiently tight joint made using wood that is "too wet" results in an open
and unsightly joint after the wood dries. Even simply moving wood products from one location to
another can cause problems. For example, face veneers on plywood made in the dry climate of
eastern Oregon may swell and buckle when they reach the more hot and humid climate of the U.S.
Southeast. All of these problems are symptoms of wood's love for moisture. See OSU Extension
publication EM8600- Wood and Moisture Relationships for more information on wood and water.
Lumber sawn fresh from a log is known as "green" and is usually saturated with moisture from the
living tree. Green lumber loses moisture until it comes into equilibrium with its surroundings. In
addition to the moisture loss from the green state, wood also undergoes constant changes in
moisture content while in service as a result of fluctuations in temperature and relative humidity.
When wood gains moisture it swells and when wood loses moisture it shrinks. The problem for the
woodworker is knowing how much a certain piece will shrink or swell based on wood species,
environmental conditions, grain orientation (see Figure 1), and piece size.
flatsawn, plainsawn
quartersawn, edge-grained,
bastard sawn
vertical grain (VG)
Figure 1. Grain orientation
Wood.xls uses published formulas (see Formulas worksheet) and dimensional change coefficients
to calculate the thickness and width change of wood based on changes in moisture content. The
user selects:
species (choice of one of 42 North American softwoods, and 61 North American hardwoods)
moisture conditions (initial and final moisture content, if known, or ambient temperature and relative humidity)
board or veneer width and thickness
grain orientation - flatsawn (works also for rotary peeled or plain-sliced), quartersawn (or quartersliced), or mixed grain.
The program calculates the dimensional change and the final board size (based on the size of the
board the user entered).
In addition to the Dimensional Change worksheet, Wood.xls has 2 other functional worksheets EMC (equilibrium moisture content) and SG & Density (specific gravity and density).
EMC calculates the equilibrium moisture content for wood given the ambient temperature and
relative humidity. This worksheet is used by the Dimensional Change worksheet to estimate initial
and/or final moisture content conditions. This worksheet also has a function to calculate moisture
content given green weight and ovendry weight.
SG & Density calculates specific gravity (SG) at user-defined moisture contents given SG green
and volumetric shrinkage. The user may select a species from the drop-down lists or enter values
in the spaces provided. The program calculates density, ovendry density of the wood, weight per
board foot at 15 percent moisture content and the weight of the water in the wood at the specified
moisture content. The terms density and SG are often used interchangeably, however these terms
have different meanings. Density is the weight per unit volume (e.g., lbs/ft 3 or kg/m3) whereas SG is
the ratio of the density of a material to the density of water and is unitless. Wood is unique in that
its weight and volume change as it gains and loses moisture. Therefore, its SG also changes. This
issue is often confusing for people wanting to estimate weight given SG. This worksheet helps to
simplify the process of estimating weight of wood at varying moisture contents. For more
information on specific gravity and other topics in wood technology, please see:
The Nature of Wood and Wood Products CD-ROM
1998. Regents of the University of Minnesota. Available from the Forest Products Society,
Madison, WI. (608) 231-2152.
How to Use Wood.xls
An Example
Consider the following example:
Let's say you plan to panel a 20 foot wide interior wall of your home with flatsawn 1x6 (actual size
3/4 inches x 5½ inches) tongue-and-groove paneling. The local home center has incense-cedar,
redwood (young-growth), and ponderosa pine, all at 19 percent moisture content. You plan to
purchase the wood and install it immediately. Let's say the temperature inside is kept relatively
constant at 72° F and the relative humidity is approximately 45 percent.
What will happen to the wood? Will it shrink, swell, or stay the same size? If it changes in size,
approximately how much will it change? Will all the species shrink or swell by the same amount?
To complete this sample exercise, start Microsoft Excel and open Wood.xls. Click on the
Dimensional Change worksheet tab.
Click on the species selection box and choose cedar, incense- for species 1, redwood, younggrowth for species 2, and pine, ponderosa for species 3.
For the initial conditions, enter 19 in the MC (%) column. Note: If only the initial temperature and
humidity conditions are known, you would enter those values instead and leave the MC (%) column
blank.
For the final conditions, enter 72 in the Temp column and 45 in the RH (%) column. For this
example, we will leave the MC (%) column blank as the final moisture content is not known. The
program will estimate final moisture content for you given ambient temperature and humidity.
The program calculates the change in moisture content and reports this value in the Change in MC
column. For this example, the change in MC is 10.565 percent.
Enter the thickness and width in the appropriate column. For this example, enter 0.75 for thickness
and 5.5 for width for all 3 species.
In the Grain Orientation column, select flatsawn for all 3 species.
The program calculates the approximate dimensional change in thickness and width and reports the
estimated final piece size. The values reported are:
Approximate
Dimensional Change in
Species
Thickness
Width
cedar, incense0.009 in
0.103 in
redwood, young-growth 0.006 in
0.097 in
pine, ponderosa
0.010 in
0.123 in
Final Size
0.741 by 5.397
0.744 by 5.403
0.740 by 5.377
Therefore, ponderosa pine will shrink the most in width at 0.123 inches or a little under 1/8 inches.
This shrinkage is due solely to moving the lumber, initially at 19 percent MC, to drier conditions
indoors. For this example, paneling a 20 ft. (240 inches) wide wall with 5½-inch material will
require:
240 ÷ 5½ = approx. 44 pieces
To calculate total shrinkage across the width of the wall, multiply the number of pieces by the
shrinkage per piece. Therefore, total shrinkage for 44 pieces will be:
44 x 0.123 = approx. 5½ inches
Across the width of a 20 ft. wide wall, the paneling will shrink nearly 5½ inches. Remember, these
numbers are estimates.
Does this mean you'll have a 5½-inch gap at one end of the wall? Because of the way the paneling
is installed (glued and/or nailed to the wall), its shrinkage in width will be restrained. What this
number tells you is how much the paneling might move if it were unrestrained, and therefore you
have a relative idea of how much stress is in the boards as their movement is restrained. The more
likely occurrence in this example will be splitting around nail holes, buckling of individual pieces, or
the opening of gaps between adjacent boards.
To get an idea of the magnitude of difference between wood species, try running the program again
except this time choose a dense hardwood like hickory or Pacific madrone.
Instructions for "wood.xls"
Scott Leavengood
Wood Products Extension Agent
This program contains 3 functional worksheets:
1. Dimensional Change
Calculates dimensional change for wood based on species, initial and final moisture content (or
temperature and relative humidity), grain orientation, and piece size (width and thickness).
a. Select species from list (user may choose up to 3 species)
b. Enter initial moisture content [MC (%)] or temperature and relative humidity [RH (%)]
MC and RH must be in percent (for example, 80 not 0.80)
[NOTE: equilibrium moisture content (EMC) is only calculated if MC is left blank]
c. Enter final moisture content [MC (%)] or temperature and relative humidity [RH (%)]
[NOTE: equilibrium moisture content (EMC) is only calculated if MC is left blank]
d. Enter thickness and width (inches or millimeters)
e. Select grain orientation
Options:
The user may add up to 10 new species. The dimensional change coefficients, percent shrinkage values,
and specific gravity values may be found in textbooks, wood software (for example, Woods of the World
CD-ROM) or other such sources. To add a species, click on the tab for the %Shrinkage & SG worksheet.
Scroll down the list to find the entry in column B, "new species1." Move the cursor to cell B113 and type
the new name. Press the arrow right key on the keyboard and enter the percentage shrinkage from green
to ovendry in the radial direction (cell C113). Arrow right and enter percent shrinkage in the tangential
direction (cell D113). Arrow right and enter the coefficient of dimensional change in the radial direction
(cell E113). Arrow right and enter the coefficient of dimensional change in the tangential direction (cell
F113). Arrow right and enter the percent volumetric shrinkage from green to ovendry (cell G113).
Cells H113 and I113 are for reference only and may be left blank (the values are not used by the
program). Arrow right to cell J113 and enter the specific gravity green. Arrow right to cell K113 and enter
the specific gravity at 12% moisture content.
To add the next species, follow the same steps beginning in cell B114 for "new species 2."
To add more than 10 new species, the user may contact the author for assistance at (503) 725-2123 or
by sending e-mail to [email protected].
2. EMC
Calculates equilibrium moisture content (EMC) given temperature and relative humidity.
a. Enter temperature in either Fahrenheit or Celsius. If in Celsius, check the box above "Temp."
b. Enter relative humidity [RH (%)] in percent
This worksheet also calculates moisture content given green weight and ovendry weight.
3. SG & Density
The program calculates specific gravity (SG) at user-selected moisture content, density, ovendry density,
density due to water, and weight per board foot at 15% MC. The user may either select the species of
interest from the drop-down boxes, or enter the values in the spaces provided.
Table 1. Green specific gravity known
a. Select species or enter green specific gravity (SGGRN)
b. Select species or enter percent volumetric shrinkage
c. Enter moisture content (MC) of interest.
d. Select nominal board dimensions to calculate weight of 1 board foot (BF) at 15% MC
Table 2. Dry specific gravity known
a. Select species or enter dry specific gravity (SG12)
b. Select species or enter percent volumetric shrinkage
c. Select nominal board dimensions to calculate weight of 1 board foot (BF) at 15% MC
The worksheets cuft per BF, %Shrinkage & SG, and Formulas are used by the program and are
available to the user as a reference.
71
83
75
1
0
3.8
flatsawn
quartersawn
Dimensional Change in Wood
INITIAL CONDITIONS
FINAL CONDITIONS
Celsius
Species
1 Douglas-fir, interior north
MC (%)
Temp
RH (%)
mixed grain
Celsius
MC (%)
RH (%)
in MC
72
45
10.565
EMC = 8.44%
2 larch, western
3 fir, grand
1
6.9
4.5
Approximate
Change
Temp
19
1
EMC = Equilibrium Moisture Content
shrink
Metric (mm)
Thickness
Width
Grain
Orientation
Dimensional Change in
Thickness
Width
Final Size
0.75
5.5
flatsawn
0.01 in
0.137 in
0.74 by 5.363
0.75
5.5
flatsawn
0.012 in
0.182 in
0.738 by 5.318
0.75
5.5
flatsawn
0.009 in
0.149 in
0.741 by 5.351
0
Note: See %Shrinkage & SG worksheet for definitions of Douglas-fir ranges
Note: Flatsawn includes plainsawn, rotary peeled, or plain-sliced.
Quartersawn includes edge-grained, vertical grained, or quarter-sliced
Mixed grain includes bastard sawn lumber. The calculated
shrink/ swell is the average of quartersawn and flatsawn.
flatsawn, plainsawn
quartersawn, edge-grained
vertical-grained (VG)
bastard sawn
Equilibrium Moisture Content (EMC)
Enter temperature and relative humidity to
calculate equilibrium moisture content (EMC)
Celsius
Temp
72
#N/A
72
RH (%)
EMC
45
8.44
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
45
#N/A
8.44
Wood Moisture Content =
Green weight 210.38
Ovendry weight 110.67
W
K
384.05760 0.81996
K1
K2
90.1%
Enter green weight and ovendry weight
to calculate moisture content
KH
K1KH K1K2K2H2
5.91110
2.66617
0.36898
2.18109
2.14569
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
384.05760 0.81996
5.91110
2.66617
0.36898
2.18109
2.14569
ovendry weight
re content
0
Converted temp
72
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
#N/A
0
#N/A
72
Specific Gravity & Density
Table 1. Green Specific Gravity (SGGRN) Known
###
% Vol.
Shrinkage
SGGRN
GRN to OD
82
juniper,
0.41 western
7.95
83
larch,
larch,
western 14
0.48western
MC (%)
118.6
100
SGMC
Metric
Density
0.41 @ 118.6% MC
0.48 @ 100% MC
#N/A @ 0% MC
#N/A @ 0% MC
% Vol.
56 lbs/ft3 @ 118.6% MC
59.9 lbs/ft3 @ 100% MC
#N/A @ 0% MC
#N/A @ 0% MC
0
Density
Density due to Water
1.76 lbs
27.81 lbs/ft3
33 lbs/ft3 @118.6% MC
2.15 lbs
#N/A
#N/A
34.84 lbs/ft3
#N/A lbs/ft3
#N/A lbs/ft3
34.8 lbs/ft3 @100% MC
#N/A
#N/A
Surfaced Dry (15% MC)
26
Weight per board foot of
Shrinkage
GRN to OD
?
Ovendry
1x6, 4/4x6
Table 2. Dry Specific Gravity (SG12) Known
SG12
2
Weight per board foot of
Density
Metric
?
Ovendry
2x4
Surfaced Dry (15% MC)
Density
Density due to Water
97
pine,
0.45radiata (Monterey)
10.4
31.5 lbs/ft3 @ 12% MC
1.75 lbs
29.3 lbs/ft3
3.5 lbs/ft3 @12% MC
70
Douglas-fir,
coast
0.48
12.4
33.6 lbs/ft3 @ 12% MC
0 lbs/ft3 @ 12% MC
0 lbs/ft3 @ 12% MC
1.87 lbs
#N/A
#N/A
31.5 lbs/ft3
#N/A
#N/A
3.8 lbs/ft3 @12% MC
#N/A
#N/A
Actual
Nominal
Width
Thickness
Width
Thickness
0.75
0.75
0.75
0.75
0.75
1.15625
1.15625
1.15625
1.15625
1.15625
1.40625
1.40625
1.40625
1.40625
1.40625
1.59375
1.59375
1.59375
1.59375
1.59375
1.8125
1.8125
1.8125
1.8125
1.8125
1.5
1.5
1.5
1.5
1.5
3.5
3.5
3.5
3.5
3.5
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
3.5
5.5
7.25
9.25
11.25
1
1
1
1
1
1.25
1.25
1.25
1.25
1.25
1.5
1.5
1.5
1.5
1.5
1.75
1.75
1.75
1.75
1.75
2
2
2
2
2
2
2
2
2
2
4
4
4
4
4
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
4
6
8
10
12
Nominal
Dim.
Surfaced Dry
1x4, 4/4x4
1x6, 4/4x6
1x8, 4/4x8
1x10, 4/4x10
1x12, 4/4x12
5/4x4
5/4x6
5/4x8
5/4x10
5/4x12
6/4x4
6/4x6
6/4x8
6/4x10
6/4x12
7/4x4
7/4x6
7/4x8
7/4x10
7/4x12
8/4x4
8/4x6
8/4x8
8/4x10
8/4x12
2x4
2x6
2x8
2x10
2x12
4x4
4x6
4x8
4x10
4x12
0.0546875
0.05729167
0.05664063
0.0578125
0.05859375
0.06744792
0.07065972
0.06985677
0.07130208
0.07226563
0.06835938
0.07161458
0.07080078
0.07226563
0.07324219
0.06640625
0.06956845
0.0687779
0.07020089
0.07114955
0.06608073
0.06922743
0.06844076
0.06985677
0.07080078
0.0546875
0.05729167
0.05664063
0.0578125
0.05859375
0.06380208
0.06684028
0.06608073
0.06744792
0.06835938
ft3/BF
1
0
2 0.057292
3
0
4
0
5
0
6
0
7
0
8
0
9
0
10
0
11
0
12
0
13
0
14
0
15
0
16
0
17
0
18
0
19
0
20
0
21
0
22
0
23
0
24
0
25
0
26
0
27
0
28
0
29
0
30
0
31
0
32
0
33
0
34
0
35
0
0.057292
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.054688
0
0
0
0
0
0
0
0
0
0.054688
Table values from the Wood Handbook: Wood as an Engineering Material. 1999.
Forest Products Society, Madison, WI,
Alden, H.A. Hardwoods of North America. 1995. General Technical Report FPL-GTR-83.
USDA Forest Service, Forest Products Laboratory, Madison, WI, and
Kininmonth, J.A. and L.J. Whitehouse. Properties and Uses of New Zealand Radiata Pine. 1991. Forest Research Institute, Rotorua, NZ.
Changes > 6-14%
Changes within 6-14%
% Vol.
Average
% Shrinkage grn to OD
Dim. Change Coeff.
Shrinkage
Green MC (%)
Radial
Tangential
Radial
Tangential
GRN to OD
Heartwood
Sapwood
SGGRN
SG12
60 walnut, black
4.4
5
4.6
4.1
3.7
4.9
3.5
6.6
5.5
6.3
4.7
6.5
7.3
3.6
3.4
3.7
3.4
3.6
3.9
4.2
4.7
4.8
4.9
5.3
4.8
4.9
7.7
7.2
7
7.6
4.8
4.2
4.6
5.6
5.2
5.4
4.7
3.7
4.8
4
3
4.8
4.4
4
4
4.7
4.4
5
6.6
5.3
5.6
7.9
4.6
4
5.3
5
4.9
5.1
4.2
5.5
7.3
7.8
7.1
8.1
6.3
7.8
6.7
9.3
11.9
8.6
9.2
9
9.5
8.1
6.4
7.1
6.7
8.6
9.2
9.5
10.2
8.1
8.9
11.6
8.9
8.9
11
11.5
10.5
12.6
9.9
6.6
7.2
12.4
8.8
6.6
8.3
7.1
9.3
8.2
7.2
9.9
11.1
9.9
8.6
11.3
9.8
9.6
9.5
12.7
10.5
11.2
8.2
6.2
10.2
8.4
11.7
8.7
7.6
7.8
0.00151
0.00172
0.00169
0.00141
0.00126
0.00169
0.00119
0.0023
0.0019
0.00219
0.00162
0.00256
0.00256
0.00123
0.00116
0.00126
0.00116
0.00123
0.00133
0.00144
0.00183
0.00165
0.00169
0.00183
0.00165
0.00169
0.00259
0.00259
0.00259
0.00259
0.00165
0.00144
0.00158
0.00194
0.0018
0.00187
0.00162
0.00126
0.00165
0.00137
0.00102
0.00165
0.00123
0.00151
0.00158
0.00158
0.00151
0.00151
0.0023
0.00183
0.0018
0.00278
0.00158
0.00137
0.00183
0.00172
0.00169
0.00176
0.00144
0.0019
0.00256
0.00274
0.00274
0.00285
0.00219
0.00274
0.00234
0.0033
0.00431
0.00304
0.00327
0.00338
0.00338
0.00285
0.00223
0.00248
0.00234
0.00304
0.00327
0.00338
0.00419
0.00285
0.00315
0.00419
0.00315
0.00315
0.00411
0.00411
0.00411
0.00411
0.00353
0.0023
0.00252
0.00451
0.00312
0.0023
0.00293
0.00248
0.00353
0.00289
0.00252
0.00353
0.0023
0.0035
0.00369
0.00369
0.0035
0.0035
0.00338
0.00462
0.00365
0.00403
0.00289
0.00216
0.00365
0.00296
0.00423
0.00308
0.00267
0.00274
12.6
15.2
12.5
13.2
12
13.3
11.5
15.8
17.2
16.2
13.5
15.6
16.8
12.5
10.6
11.5
11.6
12.4
13.9
14.6
15.4
14.9
13.8
17.7
13.8
13.6
17.8
17.9
16.7
19.2
16.9
10.8
10.2
18.1
13.6
12.3
12.9
11.6
14
12.6
12
14.7
15.1
19
13.7
16.1
16.1
18.9
14.7
16
16.3
19.1
12.7
10.3
15.8
14.1
17.3
14.4
12.5
12.8
?
95
?
?
?
46
95
81
55
89
?
75
74
?
?
58
120
162
?
95
66
44
?
?
61
?
70
71
?
?
?
?
?
?
?
?
?
?
?
?
58
65
76
?
80
83
81
82
?
?
64
?
83
?
79
114
?
87
150
90
97
?
58
?
?
44
113
133
72
72
?
70
72
?
?
?
?
146
?
92
61
57
?
?
65
?
52
49
?
?
?
?
?
?
?
?
?
?
?
?
97
72
75
?
69
75
81
74
?
?
78
?
106
?
137
130
?
115
116
73
0.37
0.45
0.53
0.5
0.48
0.55
0.35
0.32
0.56
0.48
0.49
0.6
0.55
0.33
0.36
0.47
0.4
0.31
0.37
0.46
0.59
0.57
0.48
0.6
0.49
0.6
0.64
0.66
0.64
0.62
0.5
0.6
0.66
0.58
0.44
0.46
0.42
0.44
0.52
0.49
0.44
0.56
0.56
0.56
0.56
0.52
0.56
0.56
0.8
0.57
0.6
0.64
0.4
0.42
0.46
0.46
0.58
0.46
0.46
0.51
0.41
0.49
0.56
0.55
0.52
0.6
0.38
0.37
0.64
0.55
?
0.65
0.62
0.36
0.38
0.5
0.43
0.35
0.4
0.5
0.64
0.63
0.53
0.66
0.53
0.66
0.72
0.75
0.72
0.69
0.57
?
0.69
0.65
0.48
0.5
?
0.48
0.57
0.54
0.47
0.63
0.61
0.63
0.63
0.59
0.63
0.69
0.88
0.63
0.68
0.74
0.42
0.46
0.52
0.49
?
0.5
0.5
0.55
61 willow, black
3.3
8.7
0.00112
0.00308
13.9
?
?
0.36
0.39
SPECIES
1 alder, red
2 ash, black
3 ash, green
4 ash, Oregon
5 ash, pumpkin
6 ash, white
7 aspen, quaking
8 basswood, American
9 beech, American
10 birch, paper
11 birch, river
12 birch, sweet
13 birch, yellow
14 buckeye, yellow
15 butternut
16 cherry, black
17 chestnut, American
18 cottonwood, black
19 cottonwood, eastern
20 elm, American
21 elm, cedar
22 elm, rock
23 elm, slippery
24 elm, winged
25 hackberry
26 hickory, pecan
27 hickory, mockernut
28 hickory, pignut
29 hickory, shagbark
30 hickory, shellbark
31 holly, American
32 honeylocust
33 locust, black
34 madrone, Pacific
35 magnolia, cucumbertree
36 magnolia, Southern
37 magnolia, sweetbay
38 maple, bigleaf
39 maple, black
40 maple, red
41 maple, silver
42 maple, sugar
43 oak, black
44 oak, laurel
45 oak, Northern red
46 oak, Southern red
47 oak, water
48 oak, willow
49 oak, live
50 oak, overcup
51 oak, white
52 persimmon, common
53 poplar-yellow
54 sassafras
55 sweetgum
56 sycamore, American
57 tanoak
58 tupelo, black
59 tupelo, water
62 baldcypress
63 cedar, Alaska64 cedar, Atlantic white65 cedar, eastern redcedar
66 cedar, incense67 cedar, Northern white68 cedar, Port-Orford69 cedar, western redcedar
70 Douglas-fir, coast
71 Douglas-fir, interior north
72 Douglas-fir, interior west
73 fir, balsam
74 fir, California red
75 fir, grand
76 fir, noble
77 fir, Pacific silver
78 fir, subalpine
79 fir, white
80 hemlock, eastern
81 hemlock, western
82 juniper, western
83 larch, western
84 pine, eastern white
85 pine, jack
86 pine, loblolly
87 pine, lodgepole
88 pine, longleaf
89 pine, pond
90 pine, ponderosa
91 pine, red
92 pine, shortleaf
93 pine, slash
94 pine, sugar
95 pine, Virginia
96 pine, western white
97 pine, radiata (Monterey)
98 redwood, old-growth
99 redwood, young-growth
100 spruce, black
101 spruce, Engelmann
102 spruce, red
103 spruce, Sitka
104 tamarack
105 new species1
106 new species2
107 new species3
108 new species4
109 new species5
110 new species6
111 new species7
112 new species8
113 new species9
114 new species10
3.8
2.8
2.9
3.1
3.3
2.2
4.6
2.4
4.8
3.8
4.8
2.9
4.5
3.4
4.3
4.4
2.6
3.3
3
4.2
3.3
4.5
2.1
3.7
4.8
4.3
5.1
5.1
3.9
3.8
4.6
5.4
2.9
4.2
4.1
3.4
2.6
2.2
4.1
3.8
3.8
4.3
3.7
6.2
6
5.4
4.7
5.2
4.9
6.9
5
7.6
6.9
7.5
6.9
7.9
7.5
8.3
9.2
7.4
7
6.8
7.8
4.7
9.1
6.1
6.6
7.4
6.7
7.5
7.1
6.2
7.2
7.7
7.6
5.6
7.2
7.4
7
4.4
4.9
6.8
7.1
7.8
7.5
7.4
0.0013
0.00095
0.00099
0.00106
0.00112
0.00101
0.00158
0.00111
0.00165
0.0013
0.00165
0.00099
0.00155
0.00112
0.00148
0.00151
0.00088
0.00112
0.00102
0.00144
0.00111
0.00155
0.00071
0.00126
0.00165
0.00148
0.00176
0.00165
0.00133
0.0013
0.00158
0.00187
0.00099
0.00144
0.00141
0.001
0.0012
0.00101
0.00141
0.0013
0.0013
0.00148
0.00126
0.00216
0.00208
0.00187
0.00162
0.0018
0.00229
0.00241
0.00234
0.00267
0.00241
0.00263
0.00241
0.00278
0.00245
0.00293
0.00327
0.00259
0.00245
0.00237
0.00274
0.00155
0.00323
0.00212
0.0023
0.00259
0.00234
0.00263
0.00259
0.00216
0.00252
0.00271
0.00267
0.00194
0.00252
0.00259
0.00233
0.00205
0.00229
0.00237
0.00248
0.00274
0.00263
0.00259
10.5
9.2
8.8
7.8
7.7
7.2
10.1
6.8
12.4
10.7
11.8
11.2
11.4
11
12.4
13
9.4
9.8
9.7
12.4
7.95
14
8.2
10.3
12.3
11.1
12.2
11.2
9.7
11.3
12.3
12.1
7.9
11.9
11.8
10.4
6.8
7
11.3
11
11.8
11.5
13.6
121
32
?
33
40
?
50
58
37
?
?
?
?
91
34
55
?
98
97
85
?
54
?
?
33
41
31
?
40
32
32
?
98
?
62
45
86
?
?
51
?
41
49
171
166
?
?
213
?
98
249
115
?
?
?
?
136
115
164
?
160
119
170
?
110
?
?
110
120
106
?
148
134
122
?
219
?
148
120-180
210
?
?
173
?
142
?
0.42
0.42
0.31
0.44
0.35
0.29
0.39
0.31
0.45
0.45
0.46
0.33
0.36
0.35
0.37
0.4
0.31
0.37
0.38
0.42
0.41
0.48
0.34
0.4
0.47
0.38
0.54
0.51
0.38
0.41
0.47
0.54
0.34
0.45
0.35
?
0.38
0.34
0.38
0.33
0.37
0.37
0.49
0.46
0.44
0.32
0.47
0.37
0.31
0.43
0.32
0.48
0.48
0.5
0.35
0.38
0.37
0.39
0.43
0.32
0.39
0.4
0.45
0.44
0.52
0.35
0.43
0.51
0.41
0.59
0.56
0.4
0.46
0.51
0.59
0.36
0.48
0.38
0.45
0.4
0.35
0.42
0.35
0.4
0.4
0.53
Formulas from the Wood Handbook: Wood as an Engineering Material. 1999. Forest Products Society,
and
Madison, WI
Haygreen, J.G. and Bowyer, J.L. 1989. Forest Products and Wood Science: An Introduction -
Second Edition. 1989. University of Iowa Press, Ames, IA.
Dimensional Change
The change in dimension within the moisture content limits of 6 to 14 percent is
calculated as:
Change in dimension = DI [CT(MF - MI)]
where:
DI = initial dimension (in inches or other units)
CT = dimensional change coefficient, tangential direction (for radial direction use C R)
MF = final moisture content (percent)
MI = initial moisture content (percent)
Approximate dimensional changes associated with moisture content changes larger than
6 to 14 percent, or when one value is outside of those limits, can be calculated by:
DI(MF - MI)
Change in dimension =
30(100)
ST
where:
- 30 + MI
DI = initial dimension (in inches or other units)
ST = tangential shrinkage (percent) from green to ovendry (for radial direction use S R)
MF = final moisture content (percent)
MI = initial moisture content (percent)
Note: Neither MI nor MF should exceed 30, the assumed moisture content when shrinkage
starts for most species.
Equilibrium Moisture Content (EMC)
EMC =
where:
1800
W
KH + (K1KH + 2K1K2K2H2)
1-KH
(1 + K1KH + K1K2K2H2)
W = 330 + 0.452T + 0.00415T 2
K = 0.791 + 0.000463T - 0.000000844T 2
H = relative humidity (%)
K1 = 6.34 + 0.000775T - 0.0000935T 2
K2 = 1.09 + 0.0284T - 0.0000904T 2
T = temperature (°F)
SG & Density
Specific Gravity (SG) =
where:
ODW
Weight of equal volume of water
ODW = ovendry weight of wood
SGX% MC =
SGGRN
1 - [(% vol. shrinkage green to OD)*(30 - MC)]
100
30
where:
SGGRN = green specific gravity
OD = ovendry
MC = moisture content (percent)
DensityX% MC =
where:
(SGX% MC)*(density of water)*(1+ MC/100)
density of water = 62.4 lbs/ft3
MC = moisture content (%)
Weight per board foot (BF) for S-DRY (surfaced dry, 15% MC) lumber is calculated as:
Weight/BFS-DRY = (Density15%MC)*(actual ft3/nominal BF)
where:
Density15%MC = density in lbs/ft3 at 15% moisture content
Actual ft3/nominal BF = actual cubic feet per nominal board foot, calculated as:
(actual thickness inches* actual width inches * 1ft length)/144
(nominal width * nominal thickness* 1ft length)/12
