Earthbound SlackJack: a seismic, snow and wind load holdown system for wood framed structures, Intact Structural Supply.

Compression Members
Wood Compression Members: US Factored Resistance Member Design
●Vertical members required to support the load transfer from the holdown system.
●The EB System takes advantage of 16" o.c. standard framing as a part of the compression requirements.
●All members are sized on the lower capacity of axial buckling or compression perpendicular to grain on floor plate.
●The minimum amount of compression members must equal or exceed the tension force required on each level.
●The capacities shown below are based on NDS 2018.
COMPRESSION MEMBER SELECTION - DOUGLAS FIR LARCH
FRAMING LUMBER
SIZE
(SINGLE MEMBER) 		LUMBER
GRADE		 PERP.
TO GRAIN		 LUMBER DIMENSIONS
8 FT 9 FT 10 FT 11 FT 12 FT
(133) (160) (133) (160) (133) (160) (133) (160) (133) (160)
4-inch Wall 2x4 No. 2 3,281 2,427 2,485 1,975 2,009 1,631 1,652 1,366 1,379 1,159 1,168
3x4 No. 2 5,469 4,045 4,142 3,292 3,348 2,718 2,753 2,276 2,299 1,931 1,947
4x4 No. 1 7,656 7,656 7,656 6,210 6,275 5,090 5,131 4,242 4,269 3,586 3,605
4x6 No. 1 12,031 12,031 12,031 9,730 9,838 7,981 8,049 6,654 6,699 5,627 5,658
4x8 No. 1 15,859 15,859 15,859 12,784 12,935 10,494 10,589 8,754 8,816 7,406 7,449
4x10 No. 1 20,234 20,130 20,234 16,251 16,456 13,352 13,480 11,145 11,229 9,432 9,490
4x12 No. 1 24,609 24,482 24,609 19,765 20,015 16,239 16,395 13,554 13,657 11,472 11,542
6-inch Wall 2x6 No. 2 5,156 5,156 5,156 5,156 5,156 5,156 5,156 4,745 4,916 4,125 4,238
6x4 No. 1 12,031 12,031 12,031 12,031 12,031 12,031 12,031 12,031 12,031 12,031 12,031
6x6 No. 1 18,906 18,906 18,906 18,906 18,906 18,906 18,906 18,906 18,906 18,906 18,906
6x8 No. 1 24,922 24,922 24,922 24,922 24,922 24,922 24,922 24,922 24,922 24,922 24,922
6x10 No. 1 31,797 31,797 31,797 31,797 31,797 31,797 31,797 31,797 31,797 31,609 31,797
6x12 No. 1 38,672 38,672 38,672 38,672 38,672 38,672 38,672 38,672 38,672 38,444 38,672
COMPRESSION MEMBER SELECTION - HEM FIR
FRAMING LUMBER
SIZE
(SINGLE MEMBER) 		LUMBER
GRADE		 PERP.
TO GRAIN		 LUMBER DIMENSIONS
8 FT 9 FT 10 FT 11 FT 12 FT
(133) (160) (133) (160) (133) (160) (133) (160) (133) (160)
4-inch Wall 2x4 No. 2 2,126 2,126 2,126 1,969 2,004 1,627 1,649 1,363 1,377 1,157 1,167
3x4 No. 2 3,544 3,544 3,544 3,282 3,340 2,712 2,748 2,272 2,296 1,928 1,944
4x4 No. 1 4,961 4,961 4,961 4,961 4,961 4,496 4,531 3,746 3,769 3,166 3,182
4x6 No. 1 7,796 7,796 7,796 7,796 7,796 7,049 7,108 5,876 5,915 4,968 4,995
4x8 No. 1 10,277 10,277 10,277 10,277 10,277 9,270 9,351 7,731 7,784 6,539 6,576
4x10 No. 1 13,112 13,112 13,112 13,112 13,112 11,795 11,905 9,842 9,915 8,329 8,379
4x12 No. 1 15,947 15,947 15,947 15,947 15,947 14,345 14,479 11,971 12,059 10,130 10,190
6-inch Wall 2x6 No. 2 3,341 3,341 3,341 3,341 3,341 3,341 3,341 3,341 3,341 3,341 3,341
6x4 No. 1 7,796 7,796 7,796 7,796 7,796 7,796 7,796 7,796 7,796 7,796 7,796
6x6 No. 1 12,251 12,251 12,251 12,251 12,251 12,251 12,251 12,251 12,251 12,251 12,251
6x8 No. 1 16,149 16,149 16,149 16,149 16,149 16,149 16,149 16,149 16,149 16,149 16,149
6x10 No. 1 20,604 20,604 20,604 20,604 20,604 20,604 20,604 20,604 20,604 20,604 20,604
6x12 No. 1 25,059 25,059 25,059 25,059 25,059 25,059 25,059 25,059 25,059 25,059 25,059
© 2026 Earthbound Corp., Domestic & Foreign: Patents & Patents Pending
US Patents:  7,762,030  7,665,258  7,617,642  7,340,867  7,159,366  6,951,078  6,688,058  6,494,654  6,161,350  8,186,924  8,136,318  8,112,955