Section Contents

Thickness and Performance Category

The thickness of the panel is closely linked to the the Performance Category and both have to be displayed on the panel.  The thickness of the OSB panel has to be within the minimum and maximum thickness specification for the designated Performance Category.

Thickness  requirements are based on a tolerance of ±0.8 mm (1/32”) for panels with  Performance Categories of 13/16 and less, and ±5%   for panels with Performance Categories greater than 13/16 unless a closer tolerance is determined through qualification testing.

The manufacturer’s stated thickness of a US trademarked Performance Rated OSB panel is shown as a decimal figure (0.451 IN) in inches. Metric equivalents are provided here for ease of understanding but do not appear on the trade mark.

Recommended OSB Thickness Requirements for each Performance Category






OSB Thickness Requirement



mm          inches



mm           inches

Recommended Thickness Label2


1/4 PERF  CAT     5.56          0.291     7.14         0.281

Thickness 0.225   IN

11/32 PERF CAT     7.94          0.313     9.53         0.375

Thickness 0.322   IN

3/8 PERF   CAT     8.73          0.344   10.32         0.406

Thickness 0.354   IN

7/16 PERF CAT   10.32          0.406   11.91         0.469

Thickness 0.418   IN

15/32 PERF CAT   11.11          0.438   12.70         0.500

Thickness 0.451   IN

1/2 PERF CAT   11.91          0.469   13.49         0.531

Thickness 0.483   IN

19/32 PERF CAT   14.29          0.563   15.88         0.624

Thickness 0.578   IN

5/8 PERF   CAT   15.08          0.594   16.67         0.656

Thickness 0.609   IN

23/32 PERF CAT   17.46          0.688   19.05         0.750

Thickness 0.703   IN

3/4 PERF   CAT   18.26          0.719   19.84         0.781

Thickness 0.734   IN

13/16 PERF CAT   19.84          0.781   21.43         0.844

Thickness 0.788   IN


  21.11          0.831   23.34         0.919

Thickness 0.849   IN

1 PERF   CAT   24.13          0.950   26.67         1.050

Thickness 0.970   IN

1-1/8 PERF CAT   27.15          1.069   30.00          1.181

Thickness 1.091   IN

1-1/4 PERF CAT   30.16          1.188   33.34         1.313

Thickness 1.213    IN

1 Acceptable abbreviations are PERF CAT, CAT or Category
2  The recommended thickness label for categories less than 9/16 is 3% above the minimum.  The recommended thickness label for categories greater than or equal to 9/16 are the minimum values for PS1 sanded panels.


APA in Europe Wizard

All Questions OSBPlywood

What is a ‘life cycle stage’ and how do these link to the environmental assessment of whole buildings?

How do core category rules link with environmental product declarations?

Whose responsibility is it to check that wood products being imported into the EU do not originate from illegally sourced timber supplies?

Does the EUTR require mills to provide any extra documentation for customs entry into the European Union?

Must all plywood and OSB panels carry a CE marking?

What is the definition of a construction product under the CPR?

What is a Declaration of Performance referred to under the Construction Products Regulation?

What is the difference between Structural 1 and Exposure 1?

Does structural panel siding have shear values?

What are mould and mildew, and do they compromise the integrity of engineered wood?

The CE-mark on an APA plywood panel means it conforms to European Standards – but which ones?

I want to use a Rated Sheathing panel for flooring/ roofing application, what info do I need to know?

Plywood: Span rating
OSB: Span rating

What extra strength benefits do Structural 1 OSB panels provide over standard Rated Sheathing panels?

Do APA panels give off formaldehyde?

Plywood: Formaldehyde
OSB: Formaldehyde

What is the difference between a touch-sanded panel and sanded panel?

I’d like to know how APA veneer grades match those given in the European standards

How do I correctly gauge the face appearance a plywood Siding panel?

I want to specify an APA panel for concrete formwork – what do I need to know?

Are APA panels tongue and grooved on all four edges?

I am not familiar with the term ‘Sized for Spacing’ – what is its significance?

How are Performance Category and thickness related?

I’d like to know more about a panel’s Span Rating and how it links to thickness.

Plywood: Span rating
OSB: Span rating

What is Span Rating on the APA trademark and why is it important?

Plywood: Span rating
OSB: Span rating

What is the difference between Exposure 1 and Exterior plywood panels? What are their appropriate uses?

What are the main OSB panels likely to be available in Europe?

What are the main plywood panels likely to be available in Europe?

What are the main European standards that I would need to be aware of for OSB panels?

The main standards are: EN 13986 and EN 300

What are the main European standards that I would need to be aware of for plywood panels?

The main standards are: EN 13986, EN 636, EN 314, EN 635-3