Is softwood plywood as strong as hardwood plywood?
For structural sheathing and subfloor, yes — softwood plywood meets the same span ratings and fastener-holding requirements that engineers spec for those uses. Where hardwood-face plywood pulls ahead is face hardness, dent resistance, finish quality out of press, and reuse cycles in concrete formwork. The two products solve different problems.
Is pine plywood softwood?
Yes. Pine (southern yellow pine, eastern white pine, ponderosa pine) and Douglas fir are the two most common softwood plywood face species in North America. Spruce, hemlock, cedar, and redwood appear in regional supply.
What does CDX plywood mean?
CDX is a face/back grade pair: C-face over D-back, with Exposure 1 glue. The X stood for ‘exposure,’ not exterior — CDX is an Exposure 1 panel, meaning the glue line survives extended construction wetting but the panel is designed to be enclosed. It is the most common North American structural sheathing grade.
Can I use softwood plywood for concrete formwork?
For one or two pours on small jobs, yes — CDX will form a slab edge and walk away. For more than a handful of pours, or any application requiring a smooth fair-faced concrete finish, a film-faced plantation hardwood-face panel (HDO or MDO in North America, Pro Form for Class 3 EN 636-3 jobs) is the better-economy choice.
What's the difference between softwood plywood grades A, B, C, and D?
A through D describe face veneer appearance and the allowable defects. A is sanded smooth with minor patches; B allows tight knots and small splits; C and D are unsanded with larger knots and open defects. The grade is written as a pair, face/back: AC, BC, CDX, etc. A-face panels are used where the face shows; CDX is structural and the face is hidden.
How is softwood plywood graded for span?
Span rating is a pair of numbers like 24/16 or 32/16 stamped on sheathing-grade panels. The first number is the maximum roof-rafter spacing in inches, the second is the maximum floor-joist spacing. A 32/16 panel spans 32 inches on rafters and 16 inches on joists.
