Span Rating

Span Ratings, Performance Category and Panel Thickness are key categories that need to be considered together.

Span Rating denotes the maximum recommended centre to centre spacing of supports in inches over which the panel should be placed with its strength axis across two or more supports. The span rating can be displayed in one of two ways:

  • Single number for wall (Wall-24) and floor (24 o.c.) applications
  • Fractional format where the panel is suitable for both roofing and subflooring uses such as rated sheathing 32/16 (where the left hand number represents the maximum centre to centre spacing of supports for use in roofing and the right hand number covers the maximum centre to centre spacing for subflooring applications).
  • An exception to this rule is 303 Siding (cladding) and wall only panels where span rating applies when the panels are installed vertically.
APA Rated Sheathing (unsanded) – Span Rating, Thickness and Performance Category
 Span Rating
 Typical Performance Category1
 Nominal Thickness
Recommended Thickness Label2
mm
Inches
mm

24/0

3/8

9

0.354

8.99

24/16

7/16

10

0.418

10.32

32/16

15/32

11

0.451

11.11

1/2

12

0.483

11.91

40/20

19/32

15

0.578

14.68

5/8

16

0.609

15.47

48/24

23/32

18

0.703

17.86

3/4

19

0.734

18.64

60/32

7/8

22

0.849

21.56

 Notes:
The metric (mm) measurement is not shown in the trademark but is given in this table for ease of reference.
1  The term PERFORMANCE CATEGORY is a panel specification based on the panel nominal thickness inches.
2  The recommended thickness label is displayed in inches only e.g. THICKNESS 0.578 in.
 APA Rated Sturd-I-Floor (Touch sanded) – Span Rating, Thickness and Performance Category
Span Rating
Typical
Performance Category1
Nominal Thickness
Recommended Thickness Label2
mm
Inches
mm

16 oc

19/32

15

0.578

14.68

20 oc

19/32

15

0.578

14.68

24 oc

23/32

18

0.703

17.86

32 oc

7/8

22

0.849

21.56

48 oc

1-1/8

28

1.091

27.71

 Notes:
The metric (mm) measurement is not shown in the trademark. 
1   The term PERFORMANCE CATEGORY is a panel specification based on the panel nominal thickness inches.
2   The recommended thickness label is displayed in inches only e.g. THICKNESS 0.578 in.