Mechanical Systems Installation

Joist
Mechanical Clearance

Open-web design leaves plenty of room for mechanical systems (HVAC, plumbing, electrical) to be installed within the floor frame.

Through-Truss Clearances For Mechanicals Installation
Truss Depth Type A Type B Type C
9-1/4” 3” X 9” 5” Diameter N/A
11-1/4” 5” X 5” 6-1/4” Diameter 3” X 9-1/2”
11-7/8” 5-1/2” X 5-1/2” 6-1/2” Diameter 3” X 10”
14” 6-1/2” X 6-1/2” 8” Diameter 4” X 12”
16” 6” X 12” 10” Diameter 3” X 18”
18” 8” X 12” 11-1/2” Diameter 5” X 18”
20” 10” X 12” 13-1/2” Diameter 7” X 18”
Mechanical Clearance
Open Joist™ Stock Inventory – Chase Opening Sizes

Standard chase openings shown on this chart are centered on the joist unless otherwise indicated. Custom chase opening sizes and locations are possible in some situations. Contact an Open Joist representative to discuss custom chase openings.

Joist
Length
9-1/4" Depth
Chase (+ or – 1/4")
11-7/8" Depth
Chase (+ or – 1/4")
14" Depth
Chase (+ or – 1/4")
16" Depth
Chase (+ or – 1/4")
18" Depth
Chase (+ or – 1/4")
20" Depth
Chase (+ or – 1/4")
3’ 0" 6-1/4 x 21 8-7/8 x 21 11 x 21 13 x 21 15 x 21 17 x 21
4’ 0" Center post only* Center post only* Center post only* Center post only* Center post only* Center post only*
5’ 0" 6-1/4 x 19-1/2 8-7/8 x 2-7/8 11 x 18-1/2 13 x 14-1/8 15 x 11 17 x 4-1/4
6’ 0" 6-1/4 x 7-1/4 8-7/8 x 14-3/4 11 x 6-1/8 None 15 x 23 17 x 16-1/4
7’ 0" 6-1/4 x 18-1/8 8-7/8 x 6-3/8 11 x 18-1/4 13 x 10 15 x 2-3/8 17 x 16-3/4
8’ 0" 6-1/4 x 6-3/4 8-7/8 x 18-1/4 11 x 6 13 x 21-3/8 15 x 14-3/8 17 x 1
9’ 0" 6-1/4 x 18-5/8 8-7/8 x 10-1/8 11 x 18 13 x 5-1/8 15 x 23-5/8 17 x 12
10’ 0" 6-1/4 x 22-1/2 8-7/8 x 1-5/8 11 x 5-1/2 13 x 17-1/8 15 x 6-3/4 17 x 24-1/2
11’ 0" 6-1/4 x 18-3/8 8-7/8 x 13-7/8 11 x 17-1/8 13 x 21 15 x 17-3/4 17 x 25
12’ 0" 6-1/4 x 22-1/4 8-7/8 x 22 11 x 5 13 x 7-1/4 15 x 21-3/8 17 x 9-1/4
13’ 0" 6-1/4 x 18-5/16 8-7/8 x 17-1/2 11 x 16-3/4 13 x 13-5/8 15 x 19 17 x 18-1/2
14’ 0" 6-1/4 x 22 8-7/8 x 22-1/4 11 x 20-3/4 13 x 22-7/8 15 x 10 17 x 19
15’ 0" 6-1/4 x 17-7/8 8-7/8 x 21-1/8 11 x 16-1/2 13 x 22* 15 x 22 17 x 3-1/4
16’ 0" 6-1/4 x 21-1/2 8-7/8 x 10-3/8 11 x 20-1/2 13 x 21-1/8 15 x 22-5/8 17 x 15-1/4
17’ 0" 6-1/4 x 6-3/8 8-7/8 x 19-1/2 11 x 22-5/8* 13 x 22-1/4 15 x 22-1/2* 17 x 15-5/8
18’ 0" 6-1/4 x 5-3/4 8-7/8 x 18-1/2* 11 x 19-1/2 13 x 19-3/4 15 x 22-1/2 17 x 19-3/8*
19’ 0" 6-1/4 x 6-3/8 8-7/8 x 20-1/4 11 x 19-1/4* 13 x 20-1/8 15 x 23 17 x 19-7/8
20’ 0" 6-1/4 x 5-5/8 8-7/8 x 22-3/8* 11 x 19 13 x 25-3/4* 15 x 16-3/4 17 x 23-3/4
21’ 0"   8-7/8 x 24 11 x 20-1/4 13 x 21-1/4 15 x 23-1/8 17 x 21-1/4
22’ 0"   8-7/8 x 15-3/4 11 x 20-1/4* 13 x 22-3/4 15 x 21 17 x 22-1/4*
23’ 0"   8-7/8 x 15* 11 x 19-3/4 13 x 22-11/16 15 x 17-1/4 17 x 20
24’ 0"     11 x 21-3/4* 13 x 20-3/8 15 x 21-1/8 17 x 20-1/2
25’ 0"     11 x 19-1/4 13 x 25-9/16 15 x 21-3/8 17 x 21-3/4*
26’ 0"       13 x 18-3/8 15 x 21 17 x 17
27’ 0"       13 x 24 15 x 21-1/2 17 x 23-1/4
28’ 0"       13 x 19-7/8 15 x 22 17 x 23-3/4
29’ 0"       13 x 22-3/8 15 x 21-1/2 17 x 21-5/8*
30’ 0"       13 x 23-1/16 15 x 22-3/8 17 x 22-5/8
31’ 0"         15 x 19-3/4 17 x 20-1/4
32’ 0"           17 x 7-1/4
*Not Centered