PROPERTIES OF SAWN LUMBER

3.3.1 Classification of Sawn Lumber

Подпись: Copyright © Marcel Dekker, Inc. All rights reserved.Structural Sawn Lumber size classification was discussed in Chap­ter 1 and is summarized below.

Item

Thickness (in.)

Face widths (in.)

Nominal

Minimum

dressed

Nominal

Minimum

dressed

Dry

Green

Dry

Green

Boards

1

3/4

25/32

2

1-1/2

1-9/16

1-1/4

1

1-1/32

3

2-1/2

2-9/16

1-1/2

1-1/4

1-9/32

4

3-1/2

3-9/16

5

4-1/2

4-5/8

6

5-1/2

5-5/8

7

6-1/2

6-5/8

8

7-1/4

7-1/2

9

8-1/4

8-1/2

10

9-1/4

9-1/2

11

10-1/4

10-1/2

12

11-1/4

11-1/2

14

13-1/4

13-1/2

16

15-1/4

15-1/2

Dimension

2

1-1/2

1-9/16

2

1-1/2

1-9/16

Lumber

2-1/2

2

2-1/16

3

2-1/2

2-9/16

3

2-1/2

2-9/12

4

3-1/2

3-9/16

3-1/2

3

3-1/16

5

4-1/2

4-5/8

6

5-1/2

5-5/8

8

7-1/4

7-1/2

10

9-1/4

9-1/2

12

11-1/4

11-1/2

14

13-1/4

13-1/2

16

15-1/4

15-1/2

Dimension

4

3-1/2

3-9/16

2

1-1/2

1-9/16

Lumber

4-1/2

4

4-1/16

3

2-1/2

2-9/16

4

3-1/2

3-9/16

5

4-1/2

4-5/8

6

5-1/2

5-5/8

8

7-1/4

7-1/2

10

9-1/4

9-1/2

12

11-1/4

11-1/2

14

13-1/2

16

15-1/2

Timbers

5 and

1/2 off

5 and

1/2 off

thicker wider

From National Design Specification for Wood Construction 1991

 

Подпись: Copyright © Marcel Dekker, Inc. All rights reserved.

Nominal

size

b X d

Standard

dressed

size (S4S) b X d

inches X inches

Area of Section A in2

X-X-AXIS

Y-Y-AXIS

Approximate weight in pounds per linear foot (lb/ft) of piece when density of wood equals:

Section modulus Sxx in3

Moment of inertia Ixx in4

Section modulus Syy in3

Moment of inertia

Iyy in4

25 lb/ft3

30 lb/ft3

35 lb/ft3

40 lb/ft3

45 lb/ft3

50 lb/ft3

1 x 3

3/4 X 2-1/2

1.875

0.781

0.977

0.234

0.088

0.326

0.391

0.456

0.521

0.586

0.651

1 X 4

3/4 X 3-1/2

2.625

1.531

2.680

0.328

0.123

0.456

0.547

0.638

0.729

0.820

0.911

1 X 6

3/4 X 5-1/2

4.125

3.781

10.40

0.516

0.193

0.716

0.859

1.003

1.146

1.289

1.432

1 X 8

3/4 X 7-1/4

5.438

6.570

23.82

0.680

0.255

0.944

1.133

1.322

1.510

1.699

1.888

1 X 10

3/4 X 9-1/4

6.938

10.70

49.47

0.867

0.325

1.204

1.445

1.686

1.927

2.168

2.409

1 X 12

3/4 X 11-1/4

8.438

15.82

88.99

1.055

0.396

1.465

1.758

2.051

2.344

2.637

2.930

2 X 3

1-1/2 X 2-1/2

3.750

1.563

1.953

0.938

0.703

0.651

0.781

0.911

1.042

1.172

1.302

2X 4

1-1/2 X 3-1/2

5.250

3.063

5.359

1.313

0.984

0.911

1.094

1.276

1.458

1.641

1.823

2 X 5

1-1/2 X 4-1/2

6.750

5.063

11.39

1.688

1.266

1.172

1.406

1.641

1.875

2.109

2.344

2X 6

1-1/2 X 5-1/2

8.250

7.563

20.80

2.063

1.547

1.432

1.719

2.005

2.292

2.578

2.865

2X 8

1-1/2 X 7-1/4

10.88

13.14

47.63

2.719

2.039

1.888

2.266

2.643

3.021

3.398

3.776

2 X 10

1-1/2 X 9-1/4

13.88

21.39

98.93

3.469

2.602

2.409

2.891

3.372

3.854

4.336

4.818

2 X 12

1-1/2 X 11-1/4

16.88

31.64

178.0

4.219

3.164

2.930

3.516

4.102

4.688

5.273

5.859

2 X 14

1-1/2 X 13-1/4

19.88

43.89

290.8

4.969

3.727

3.451

4.141

4.831

5.521

6.211

6.901

3X 4

2-1/2 X 3-1/2

8.750

5.104

8.932

3.646

4.557

1.519

1.823

2.127

2.431

2.734

3.038

3X 5

2-1/2 X 4-1/2

11.25

8.438

18.98

4.688

5.859

1.953

2.344

2.734

3.125

3.516

3.906

3X 6

2-1/2 X 5-1/2

13.75

12.60

34.66

5.729

7.161

2.387

2.865

3.342

3.819

4.297

4.774

3X 8

2-1/2 X 7-1/4

18.13

21.90

79.39

7.552

9.440

3.147

3.776

4.405

5.035

5.664

6.293

3 X 10

2-1/2 X 9-1/4

23.13

35.65

164.9

9.635

12.04

4.015

4.818

5.621

6.424

7.227

8.030

3 X 12

2-1/2 X 11-1/4

28.13

52.73

296.6

11.72

14.65

4.883

5.859

6.836

7.813

8.789

9.766

3 X 14

2-1/2 X 13-1/4

33.13

73.15

484.6

13.80

17.25

5.751

6.901

8.051

9.201

10.35

11.50

3 X 16

2-1/2 X 15-1/4

38.13

96.90

738.9

15.89

19.86

6.619

7.943

9.266

10.59

11.91

13.24

4X 4

3-1/2 X 3-1/2

12.25

7.146

12.51

7.146

12.51

2.127

2.552

2.977

3.403

3.828

4.253

4X 5

3-1/2 X 4-1/2

15.75

11.81

26.58

9.188

16.08

2.734

3.281

3.828

4.375

4.922

5.469

4X 6

3-1/2 X 5-1/2

19.25

17.65

48.53

11.23

19.65

3.342

4.010

4.679

5.347

6.016

6.684

4X 8

3-1/2 X 7-1/4

25.38

30.66

111.1

14.80

25.90

4.405

5.286

6.168

7.049

7.930

8.811

4 X 10

3-1/2 X 9-1/4

32.38

49.91

230.8

18.89

33.05

5.621

6.745

7.869

8.993

10.12

11.24

4 X 12

3-1/2 X 11-1/4

39.38

73.83

415.3

22.97

40.20

6.836

8.203

9.570

10.94

12.30

13.67

4 X 14

3-1/2 X 13-1/2

47.25

106.3

717.6

27.56

48.23

8.203

9.844

11.48

13.13

14.77

16.41

4 X 16

3-1/2 X 15-1/2

54.25

140.1

1086.1

31.64

55.38

9.42

11.30

13.19

15.07

16.95

18.84

Nominal

size

b x d

Standard

dressed

size (S4S) b x d

inches x inches

Area of Section A in2

X-X-AXIS

Y-Y-AXIS

Approximate weight in pounds per linear foot (lb/ft) of piece when density of wood equals:

Section modulus Sxx in3

Moment of inertia I„ in4

Section modulus Syy in3

Moment of inertia

Iyy in4

25 lb/ft3

30 lb/ft3

35 lb/ft3

40 lb/ft3

45 lb/ft3

50 lb/ft3

5 x 5

4-1/2 x 4-1/2

20.25

15.19

34.17

15.19

34.17

3.516

4.219

4.922

5.625

6.328

7.031

6 x 6

5-1/2 x 5-1/2

30.25

27.73

76.26

27.73

76.26

5.252

6.302

7.352

8.403

9.453

10.50

6 x 8

5-1/2 x 7-1/2

41.25

51.56

193.4

37.81

104.0

7.161

8.594

10.03

11.46

12.89

14.32

6 x 10

5-1/2 x 9-1/2

52.25

82.73

393.0

47.90

131.7

9.071

10.89

12.70

14.51

16.33

18.14

6 x 12

3-1/2 x 11-1/2

63.25

121.2

697.1

57.98

159.4

10.98

13.18

15.37

17.57

19.77

21.96

6 x 14

5-1/2 x 13-1/2

74.25

167.1

1128

68.06

187.2

12.89

15.47

18.05

20.63

23.20

25.78

6 x 16

5-1/2 x 15-1/2

85.25

220.2

1707

78.15

214.9

14.80

17.76

20.72

23.68

26.64

29.60

6 x 18

5-1/2 x 17-1/2

96.25

280.7

2456

88.23

242.6

16.71

20.05

23.39

26.74

30.08

33.42

6 x 20

5-1/2 x 19-1/2

107.3

348.6

3398

98.31

270.4

18.62

22.34

26.07

29.79

33.52

37.24

6 x 22

5-1/2 x 21-1/2

118.3

423.7

4555

108.4

298.1

20.53

24.64

28.74

32.85

36.95

41.06

6 x 24

5-1/2 x 23-1/2

129.3

506.2

5948

118.5

325.8

22.44

26.93

31.41

35.90

40.39

44.88

8x 8

7-1/2 x 7-1/2

56.25

70.31

263.7

70.31

263.7

9.766

11.72

13.67

15.63

17.58

19.53

8 x 10

7-1/2 x 9-1/2

71.25

112.8

535.9

89.06

334.0

12.37

14.84

17.32

19.79

22.27

24.74

8 x 12

7-1/2 x 11-1/2

86.25

165.3

950.5

107.8

404.3

14.97

17.97

20.96

23.96

26.95

29.95

8 x 14

7-1/2 x 13-1/2

101.3

227.8

1538

126.6

474.6

17.58

21.09

24.61

28.13

31.64

35.16

8 x 16

7-1/2 x 15-1/2

116.3

300.3

2327

145.3

544.9

20.18

24.22

28.26

32.29

36.33

40.36

8 x 18

7-1/2 x 17-1/2

131.3

382.8

3350

164.1

615.2

22.79

27.34

31.90

36.46

41.02

45.57

8 x 20

7-1/2 x 19-1/2

146.3

475.3

4634

182.8

685.5

25.39

30.47

35.55

40.63

45.70

50.78

8 x 22

7-1/2 x 21-1/2

161.3

577.8

6211

201.6

755.9

27.99

33.59

39.19

44.79

50.39

55.99

8 x 24

7-1/2 x 23-1/2

176.3

690.3

8111

220.3

826.2

30.60

36.72

42.84

48.96

55.08

61.20

10 x 10

9-1/2 x 9-1/2

90.25

142.9

678.8

142.9

678.8

15.67

18.80

21.94

25.07

28.20

31.34

10 x 12

9-1/2 x 11-1/2

109.3

209.4

1204

173.0

821.7

18.97

22.76

26.55

30.35

34.14

37.93

10 x 14

9-1/2 x 13-1/2

128.3

288.6

1948

203.1

964.5

22.27

26.72

31.17

35.63

40.08

44.53

10 x 16

9-1/2 x 15-1/2

147.3

380.4

2948

233.1

1107

25.56

30.68

35.79

40.90

46.02

51.13

10 x 18

9-1/2 x 17-1/2

166.3

484.9

4243

263.2

1250

28.86

34.64

40.41

46.18

51.95

57.73

10 x 20

9-1/2 x 19-1/2

185.3

602.1

5870

293.3

1393

32.16

38.59

45.03

51.46

57.89

64.32

10 x 22

9-1/2 x 21-1/2

204.3

731.9

7868

323.4

1536

35.46

42.55

49.64

56.74

63.83

70.92

10 x 24

9-1/2 x 23-1/2

223.3

874.4

10270

353.5

1679

38.76

46.51

54.26

62.01

69.77

77.52

12 X 12

11-1/2 X 11-1/2

132.3

253.5

1458

253.5

1458

22.96

27.55

32.14

36.74

41.33

45.92

12 X 14

11-1/2 X 13-1/2

155.3

349.3

2358

297.6

1711

26.95

32.34

37.73

43.13

48.52

53.91

12 X 16

11-1/2 X 15-1/2

178.3

460.5

3569

341.6

1964

30.95

37.14

43.32

49.51

55.70

61.89

12 X 18

11-1/2 X 17-1/2

201.3

587.0

5136

385.7

2218

34.94

41.93

48.91

55.90

62.89

69.88

12 X 20

11-1/2 X 19-1/2

224.3

728.8

7106

429.8

2471

38.93

46.72

54.51

62.29

70.08

77.86

12 X 22

11-1/2 X 21-1/2

247.3

886.0

9524

473.9

2725

42.93

51.51

60.10

68.68

77.27

85.85

12 X 24

11-1/2 X 23-1/2

270.3

1058

12440

518.0

2978

46.92

56.30

65.69

75.07

84.45

93.84

14 X 14

13-1/2 X 13-1/2

182.3

410.1

2768

410.1

2768

31.64

37.97

44.30

50.63

56.95

63.28

14 X 16

13-1/2 X 15-1/2

209.3

540.6

4189

470.8

3178

36.33

43.59

50.86

58.13

65.39

72.66

14 X 18

13-1/2 X 17-1/2

236.3

689.1

6029

531.6

3588

41.02

49.22

57.42

65.63

73.83

82.03

14 X 20

13-1/2 X 19-1/2

263.3

855.6

8342

592.3

3998

45.70

54.84

63.98

73.13

82.27

91.41

14 X 22

13-1/2 X 21-1/2

290.3

1040

11180

653.1

4408

50.39

60.47

70.55

80.63

90.70

100.8

14 X 24

13-1/2 X 23-1/2

317.3

1243

14600

713.8

4818

55.08

66.09

77.11

88.13

99.14

110.2

16 X 16

15-1/2 X 15-1/2

240.3

620.6

4810

620.6

4810

41.71

50.05

58.39

66.74

75.08

83.42

16 X 18

15-1/2 X 17-1/2

271.3

791.1

6923

700.7

5431

47.09

56.51

65.93

75.35

84.77

94.18

16 X 20

15-1/2 X 19-1/2

302.3

982.3

9578

780.8

6051

52.47

62.97

73.46

83.96

94.45

104.9

16 X 22

15-1/2 X 21-1/2

333.3

1194

12840

860.9

6672

57.86

69.43

81.00

92.57

104.1

115.7

16 X 24

15-1/2 X 23-1/2

364.3

1427

16760

941.0

7293

63.24

75.89

88.53

101.2

113.8

126.5

18 X 18

17-1/2 X 17-1/2

306.3

893.2

7816

893.2

7816

53.17

63.80

74.44

85.07

95.70

106.3

18 X 20

17-1/2 X 19-1/2

341.3

1109

10810

995.3

8709

59.24

71.09

82.94

94.79

106.6

118.5

18 X 22

17-1/2 X 21-1/2

376.3

1348

14490

1097

9602

65.32

78.39

91.45

104.5

117.6

130.6

18 X 24

17-1/2 X 23-1/2

411.3

1611

18930

1199

10500

71.40

85.68

99.96

114.2

128.5

142.8

20 X 20

19-1/2 X 19-1/2

380.3

1236

12050

1236

12050

66.02

79.22

92.42

105.6

118.8

132.0

20 X 22

19-1/2 X 21-1/2

419.3

1502

16150

1363

13280

72.79

87.34

101.9

116.5

131.0

145.6

20 X 24

19-1/2 X 23-1/2

458.3

1795

21090

1489

14520

79.56

95.47

111.4

127.3

143.2

159.1

22 X 22

21-1/2 X 21-1/2

462.3

1656

17810

1656

17810

80.25

96.30

112.4

128.4

144.5

160.5

22 X 24

21-1/2 X 23-1/2

505.3

1979

23250

1810

19460

87.72

105.3

122.8

140.3

157.9

175.4

24 X 24

23-1/2 X 23-1/2

552.3

2163

25420

2163

25420

95.88

115.1

134.2

153.4

172.6

191.8

From National Design Specification for Wood Construction 1991

3. Posts and timbers: Cross section is approximately 5 x 5 in. square or larger, and width > thickness + 2 in. (not more) Decking: 2 in. < thickness < 4 in. with load applied to wide face of board

All sizes referred to in the previous classification are the nom­inal, or stated, sizes. However, most lumber is called dressed lum­ber, which means the members are surfaced to a standard net size. Structural computations to determine the required size of mem­bers are based on the net dimensions (actual sizes), not the nomi­nal size. Sizes of members is further discussed in Section 3.3.2.