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Where speed meets strength.

Open Joist™Flat Roof Spans

The following charts show maximum clear spans for Open Joist™ trusses used for "flat" roof framing. Varied loading conditions and truss spacing options are included. For loading conditions and situations not included in these charts, contact Open Joist Engineering.

· 9-1/4" Truss Depth
· 11-7/8" Truss Depth
· 14" Truss Depth
· 16" Truss Depth

9-1/4" Truss Depth*
 9-1/4" Depth Maximum Live Load Deflection - L/360 & L/480, 1-1/2" Minimum Bearing Each End

Chord* Size

Chord* Grade
   Loading (PSF)
      12" o.c.
      16" o.c.
    19.2" o.c.
     24" o.c.
Live
Dead
L/360
L/480
L/360
L/480
L/360
L/480
L/360
L/480
3x2
#2
40
25
15'-9"
15'-9"
15'-9"
14'-11"
15'-6"
14'-0"
14'-2"
12'-10"
4x2
MSR 2100
40
25
19'-9"
19'-5'
18'-9"
17'-3"
17'11"
16'-6"
15'-3"
3x2
#2
50
25
15'-9"
15'-3"
15'-3"
13'-9"
14'-3"
12'-10"
13'-0"
11'-11"
4x2
MSR 2100
50
25
19'-9"
17'-11"
17'-11"
16'-4"
16'-6"
3x2
#2
100
25
13'-2"
11'-11"
11'-11"
10'-8"
10'-5"
9'-11"
8'-6"
8'-6"

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11-7/8" Truss Depth*

 11-7/8" Depth Maximum Live Load Deflection - L/360 & L/480, 1-1/2" Minimum Bearing Each End
Chord* Size
  Chord* Grade
   Loading (PSF)
12" o.c.
16" o.c.
19.2" o.c.
24" o.c.
   
Live
Dead
L/360
L/480
L/360
L/480
L/360
L/480
L/360
L/480
3x2
#2
40
25
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-8"
16'-9"
15'-2"
4x2
#2
40
25
18'-9"
18'-9"
18'-9"
18'-9"
18'-9"
18'-1"
17'-7"
4x2
MSR 2100
40
25
22'-9"
22'-9"
22'-0"
21'-1"
20'-10"
20'-0"
3x2
#2
50
25
16'-9"
16'-9"
16'-9"
16'-5"
16'-1"
15'-2"
14'-1"
14'-1"
4x2
#2
50
25
18'-9"
18'-9"
18'-5"
18'-5"
17'-0"
17'-0"
4x2
MSR 2100
50
25
22'-9"
21'-6"
21'-4"
19'-9"
19'-3"
3x2
#2
100
25
15'-7"
14'-1"
13'-1"
12'-9"
11'-7"
11'-7"
9'-8"
9'-8"

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14" Truss Depth*
 14" Depth Maximum Live Load Deflection - L/360 & L/480, 1-1/2" Minimum Bearing Each End
Chord* Size
  Chord* Grade
Loading (PSF)
12" o.c.
16" o.c.
19.2" o.c.
24" o.c.
 
 
Live
Dead
L/360
L/480
L/360
L/480
L/360
L/480
L/360
L/480
3x2
#2
40
25
17'-9"
17'-9"
17'-9"
17'-9"
17'-9"
17'-9"
16'-4"
16'-4"
4x2
#2
40
25
20'-9"
20'-9"
20'-9"
20'-9"
19'-9"
19'-9"
17'-4"
17'-4"
4x2
MSR 2100
40
25
24'-9"
24'-9"
24'-8"
22'-9"
23'-5"
21'-3"
21'-4"
3x2
#2
50
25
17'-9"
17'-9"
17'-9"
17'-7"
17'-1"
16'-5"
15'-2"
15'-2"
4x2
#2
50
25
20'-9"
20'-9"
20'-4"
19'-8"
18'-2"
18'-2"
4x2
MSR 2100
50
25
24'-9"
23'-2"
22'-10"
21'-0"
20'-1"
3x2
#2
100
25
16'-8"
15'-3"
14'-8"
13'-9"
12'-7"
12'-7"
10'-8"
10'-8"
4x2
#2
100
25
17'-9"

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16" Truss Depth*
 16" Depth Maximum Live Load Deflection - L/360 & L/480, 1-1/2" Minimum Bearing Each End
Chord* Size
Chord* Grade
Loading (PSF)
12" o.c.
16" o.c.
19.2"o.c.
24" o.c.
Live
Dead
L/360
L/480
L/360
L/480
L/360
L/480
L/360
L/480
3x2
#2
40
25
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
4x2
#2
40
25
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
4x2
MSR 2100
40
25
25'-9"
25'-9"
25'-9"
25'-9"
25'-9"
25'-6"
23'-10"
4x2
MSR 2400
40
25
29'-9"
29'-8"
29'-9"
27'-7"
28'-5"
26'-0"
23'-10"
3x2
#2
50
25
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
16'-9"
4x2
#2
50
25
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
21'-9"
21'-6"
21'-0"
4x2
MSR 2100
50
25
25'-9"
25'-9"
25'-9"
25'-0"
24'-10"
22'-5"
4x2
MSR 2400
50
25
29'-9"
28'-2"
28'-2"
3x2
#2
100
25
16'-9"
16'-9"
14'-8"
14'-8"
12'-7"
12'-7"
10'-8"
10'-8"
4x2
#2
100
25
21'-9"
20'-0"
20'-0"
19-0"
4x2
MSR 2100
100
25
23'-5"

* Because Open Joist is a "stock" product, the length of an Open Joist truss determines the size and grade of the truss chords (see tables). Maximum spans published on the chart above may be limited by standard joist configuration. To find maximum clear span for each truss depth in a given loading condition, refer to the bottom line of spans shown for that load condition.

NOTE: Clear spans shown on this chart are presented under the following conditions: (1) Bearing of 1-1/2"; (2) "Strongback" bracing is not considered; (3) Assumes a single layer of APA-rated wood sheathing is nailed or screwed; (4) Spans are clear distance between supports for uniformly loaded trusses and include allowable increases for repetitive use members.

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