Section Contents

Plyform: Species Strength Group Ensures Performance

Concrete form panels must only be made from certain wood species and veneer grades to ensure they have sufficient strength to support the weight of the wet concrete.  The information here is adapted from APA’s Concrete Forming Design/Construction Guide.

Species Group:
  • The panels’ face and back require one of the strongest species:  Group 1, 2 or 3, depending on bending strength and stiffness.
  • Group 1 is the strongest.
  • The choice of species is particularly important  in non-overlaid plywood, where the veneer is in direct contact with the concrete.
  • Species such as Western Larch should be avoided because their high sugar content can prevent the concrete from setting.
  • High sugar content is not a concern with HDO and special MDO plywood.  The overlay on top of the face veneer means it is not in direct contact with the concrete.
Concrete Plyform Panel Types

Class 1

Class 2

(suitable for most standard applications)

Structural 1

option (i)

option (ii)

B-B B-C HDO MDO Veneer Species Group Minimum Grade Species Group Minimum Grade Species Group Minimum Grade Species Group Minimum Grade
Face 1a Bcsanded 1a or 2 Bcsanded 3asanded Bc sanded Min. 3.2mm (1/8”) veneer thickness before sanding1 1a Bc sanded
Cross Band 1 or 2 C 1,2, 3 or 4 C 1,2,3 C 1 C
Centre 1,2,3 or 4 C 1,2,3 or 4 C 1,2,3 or 4 C 1 C
Back 1a Ccsanded 1a or 2b Ccsanded 3asanded Cc sanded Min. 3.2mm (1/8”) veneer thickness before sanding1 1a Bc sanded

a refers to Western Larch excluded from all face veneers  b same species group as face veneer  c indicates that with this grade, there is a mill-applied release agent