CODES

ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

Part I ‒ Administrative

Part II ‒ Definitions

Part III ‒ Building Planning and Construction

Part IV ‒ Energy Conservation

Part V ‒ Mechanical

Part VI ‒ Fuel Gas

Part VII ‒ Plumbing

Part VIII ‒ Electrical

Part IX ‒ Referenced Standards

Heads up: There are no suggested sections in this chapter.
Heads up: There are no amended sections in this chapter.

Appendix W Basic Load Estimating

AMENDMENT
This section has been amended at the state or city level.
This appendix is a North Carolina addition and not part of the 2015 International Residential Code.

There will be no underlined text.

(The provisions contained in this appendix are adopted as part of this code.)


SECTION A-A                            SECTION B-B
For SI: 1 inch = 25.4, 1 foot = 304.8 mm, 1 square foot = 0.0929 m2.

ASSUMPTIONS (sleeping area live load; roof or stick frame rafters with no interior bearing):

Loads

Secondary floor level is 30# L.L. + 10# D.L. = 40#/sq. ft.

Attic level is 20# live load + 10# dead load = 30#/sq. ft.

Nook ceiling is 10# dead load (No attic storage) = 10#/sq. ft.

Wall load

Studs @ 16", 1/2" gypsum = 8#/sq. ft.

Roof load

20# live load + 10# dead load = 30#/sq. ft.

EXAMPLE OF LOAD ESTIMATING LOAD ON BEAM IN FAMILY ROOM
Loads in Section A - A as
follows:
(in pounds/linear foot)
Total Loads
2nd floor load
Interior wall load = Wall weight per square foot × wall height = LOAD/linear foot
= 8 pounds/sq. ft. × 8 ft. = 64 pounds/linear foot
(Wall weight can vary. Verify actual weight of materials used)
Attic load
Roof load: No roof load is transmitted to the beam in the family room. Roof Load = 0
Total Load on Beam in Family Room = 834 pounds/1foot


Beam span in family room is 9 feet and total estimated load is 834#/linear foot:

By using Table W-1, the required beam is 4 @ 2 × 12 SPF

OR

By using Table W-2, the required minimum flitch beam is 2@2 × 8 with 5/8" × 7" steel plate bolted with 1/2" bolts spaced at 2' o.c.

EXAMPLE OF LOAD ESTIMATING LOAD ON BEAM IN NOOK AREA
Loads in Section B - B as
follows:
(in pounds/linear foot)
Total Loads
2nd floor load
Interior wall load = Wall weight per square foot × wall height = LOAD/linear foot
8 pounds/sq. ft. × 8 ft. = 64 pounds/linear foot
(Wall weight can vary. Verify actual weight of materials used)
Attic load
Roof load:
Nook Ceiling load
Nook Roof load


Total Load on Beam in Nook = 884 pounds/1ft.

Beam span in nook is 8 feet and total estimated load is 884#/linear foot:

By using Table W-1, the required beam is 4 @ 2 × 12 Southern pine or 4 @ 2 × 12 Spruce-pine-fir

OR

By using Table W-2, the required minimum flitch beam is 2 @ 2 × 8 with 1/2" × 7" steel plate bolted with 1/2" bolts spaced at 2' o.c.

TABLE W-1
WOOD BEAMS AND GIRDERS ALLOWABLE LOADS IN POUNDS PER LINEAR FOOTa, b, c, d
2 × 8 (11/2" × 71/4")
Span Lf (feet) Spruce-Pine-Fire Southern Pine
2 ply 3 ply 4 ply 2 ply 3 ply 4 ply
3 1305 1956 2610 1692 2538 3383
4 979 1468 1958 1013 1519 2026
5 736 1104 1472 648 972 1296
9 511 767 1022 450 675 900
7 375 563 751 331 496 661
8 287 431 575 253 380 506
9 227 341 454 200 300 400
10 184 276 368 162 243 324
12 114 172 228 113 169 225
14 72 108 144 72 108 144
2 × 10 (11/2" × 91/4")
Span Lf (feet) Spruce-Pine-Fire Southern Pine
2 ply 3 ply 4 ply 2 ply 3 ply 4 ply
3 1665 2498 3330 2158 3238 4317
4 1249 1873 2498 1426 2139 2852
5 999 1499 1998 913 1369 1825
6 763 1144 1525 634 951 1268
7 560 840 1120 466 698 931
8 429 643 858 357 535 713
9 339 508 678 282 423 563
10 275 412 549 228 342 456
12 191 286 381q 158 238 317
14 140 210 280 116 175 233
2 × 12 (11/2" × 111/4")
Span Lf (feet) Spruce-Pine-Fire Southern Pine
2 ply 3 ply 4 ply 2 ply 3 ply 4 ply
3 2025 3038 4050 2625 3938 5250
4 1519 2278 3038 1969 2953 3938
5 1215 1823 2430 1266 1898 2531
6 1013 1519 2025 879 1318 1756
7 753 1130 1507 646 969 1291
8 577 856 1154 494 742 989
9 456 684 911 391 586 781
10 369 554 738 316 475 633
12 256 385 513 220 330 439
14 188 283 377 161 242 323
Notes:
  1. Lumber grade is #2 intended for an in-service moisture content of 19% or less.
  2. Deflection is limited to L/360.
  3. Load duration factor used in calculations is 1.0.
  4. Adequate bearing and lateral support for the member must be provided. Support for the member ends must provide a continuous load path from the bearing to the foundation.
  5. Values tabulated are for Spruce-Pine-Fir, not Spruce-Pine-Fir (South). Values tabulated for Southern Pine are based on design values published by the American Wood Council in an addendum to NDS dated March 2013.
  6. Span, L, is clear span. Effective span for bending and deflection is clear span plus 3 inches.
TABLE W-2
FLITCH PLATE BEAM ALLOWABLE LOADS IN POUNDS PER LINEAR FOOTa, b, c, d, e
(2) 2 × 6 with Plate Indicated
Span (ft.)f Plate Size/(Beam Weight per Foot)
1/4" × 5" Plate (8 lb./ft.) 3/8" × 5" Plate (10 lb./ft.) 1/2" × 5" Plate (13 lb./ft.) 5/8" × 5" Plate (15 lb./ft.) 3/4" × 5" Plate (17 lb./ft.)
6'-0" 643 825 1006 1188 1370
7'-0" 473 606 739 873 1006
8'-0" 362 464 566 668 771
9'-0" 272 348 425 502 579
10'-0" 198 198 310 366 422
11'-0" 149 191 233 275 317
12'-0" 115 147 179 212 244
(2) 2 × 8 with Plate Indicated
Span (ft.)f Plate Size/(Beam Weight per Foot)
1/4" × 7" Plate (11 lb./ft.) 3/8" × 7" Plate (14 lb./ft.) 1/2" × 7" Plate (17 lb./ft.) 5/8" × 7" Plate (20 lb./ft.) 3/4" × 7" Plate (23 lb./ft.)
6'-0" 1150 1499 1849 2199 2549
7'-0" 845 1102 1359 1615 1872
8'-0" 647 843 1040 1237 1434
9'-0" 511 666 822 977 1133
10'-0" 414 540 666 792 917
11'-0" 342 446 550 654 758
12'-0" 287 375 462 550 637
13'-0" 230 300 369 439 509
14'-0" 184 240 296 352 408
15'-0" 150 195 240 286 331
16'-0" 123 161 198 236 273
(2) 2 × 10 with Plate Indicated
Span (ft.)f Plate Size/(Beam Weight per Foot)
1/4" × 9" Plate (14 lb./ft.) 3/8" × 9" Plate (18 lb./ft.) 1/2" × 9" Plate (22 lb./ft.) 5/8" × 9" Plate (26 lb./ft.) 3/4" × 9" Plate (30 lb./ft.)
6'-0" 1642 2145 2649 3153 3657
7'-0" 1206 1576 1946 2317 2687
8'-0" 923 1207 1490 1774 2057
9'-0" 730 954 1177 1401 1625
10'-0" 591 772 954 1135 1317
11'-0" 488 638 788 938 1088
12'-0" 410 536 662 788 914
13'-0" 350 457 564 672 779
14'-0" 302 394 487 579 672
15'-0" 263 343 424 504 585
16'-0" 231 302 373 443 514
17'-0" 204 267 330 393 456
18'-0" 182 238 294 350 406
19'-0" 155 203 250 298 345
20'-0" 133 174 214 255 296
(2) 2 × 12 with Plate Indicated
Span (ft.)f Plate Size/(Beam Weight per Foot)
1/4" × 11" Plate (18 lb./ft.) 3/8" × 11" Plate (22 lb./ft.) 1/2" × 11" Plate (27 lb./ft.) 5/8" × 11" Plate (32 lb./ft.) 3/4" × 11" Plate (36 lb./ft.)
6'-0" 2297 3006 3715 4425 5134
7'-0" 1688 2209 2730 3251 3772
8'-0" 1292 1691 2090 2489 2888
9'-0" 1021 1336 1651 1966 2282
10'-0" 827 1082 1338 1593 1848
11'-0" 683 894 1105 1316 1527
12'-0" 574 752 929 1106 1283
13'-0" 489 640 791 943 1094
14'-0" 422 552 682 813 943
15'-0" 367 481 594 708 821
16'-0" 323 423 522 622 722
17'-0" 286 374 463 551 639
18'-0" 255 334 413 492 570
19'-0" 229 300 371 441 512
20'-0" 207 271 334 398 462
21'-0" 188 245 303 361 419
22'-0" 171 224 276 329 382
23'-0" 156 205 253 301 349
24'-0" 140 183 226 269 312
Notes:
  1. Lumber species and grade is #2 Southern Pine intended for an in-service moisture content of 19% or less. Design values used were published by the American Wood Council in an addendum to NDS dated March 2013. For Spruce-Pine-Fir lumber using the tabulated flitch plate allowable loads will be slightly conservative.
  2. Tabulated values are based on ASTM A36 structural steel plate.
  3. Deflection is limited to L/360.
  4. Load duration factor used in calculations is 1.0.
  5. Adequate bearing and lateral support for the member must be provided. Support for the member ends must provide a continuous load path from the bearing to the foundation.
  6. Span, L, is center to center of supports. Wood side plates and steel flitch plates shall be continuous throughout the span.
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