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# Ducts or Pipes through Steel Joists - Maximum Sizes

Maximum duct or pipe sizes through steel joists of K type:

Maximum Duct or Pipe Sizes through Steel Joists of K type
Joists Dept
(in)

Duct or Pipe Size
Round
(in)

Square
(in)

Rectangular
(in)

8 5 4 x 4 3 x 8
10 6 5 x 5 3 x 8
12 7 6 x 6 4 x 9
14 8 6 x 6 4 x 9
16 9 7 x 7 6 x 10
18 11 8 x 8 7 x 11
20 11 9 x 9 7 x 12
22 12 9 x 9 8 x 12
24 13 10 x 10 8 x 13

K series are common open web joists, standard sized for typical applications. K types span from 8’ to 60’ across with depths of 8” to 30”.

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