Janka Wood Hardness Scale vs. Plywood & OSB Panels
Comparing 2 standards across 15 specifications. 15 key differences identified.
The Janka Wood Hardness Scale is standardized under ASTM D143 (and ISO 3350) by measuring the exact force (in pounds-force / lbf or Newtons) required to embed an 11.28 mm (0.444 in) steel ball to half its diameter into a wood sample, establishing the international benchmark for hardwood flooring and lumber dent resistance.
Structural wood panels including softwood plywood and Oriented Strand Board (OSB) are standardized under Voluntary Product Standards DOC PS 1 and PS 2. Sized in standard 4×8 ft (1219×2438 mm) sheets, panels are classified by 'Performance Category' thickness with a -1/32" decimal reduction, where a nominal 1/2" panel measures 15/32" (0.469" / 11.9 mm).
Specification Comparison Table
15 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
ASTM D143 Section 13 (Hardness Test) / ISO 3350 / USDA Forest Products Laboratory (FPL) | DOC PS 1 (Plywood) / DOC PS 2 (OSB) / APA PR-N108 |
|
Test Metric Definition
|
Force in pounds-force (lbf) to embed an 11.28 mm (0.444 in / 100 mm² area) steel ball into wood at 12% moisture content | — |
|
Red Oak Industry Benchmark
|
1,290 lbf (5,740 N) | The universal 100% benchmark standard against which all flooring is compared | — |
|
Softwoods (Pine / Fir / Cedar)
|
Eastern White Pine: 380 lbf | Douglas Fir: 660 lbf | Southern Yellow Pine: 690 lbf | — |
|
Medium Domestic Hardwoods
|
Black Walnut: 1,010 lbf | Black Cherry: 950 lbf | Teak: 1,155 lbf | — |
|
Hard Domestic Standards
|
White Oak: 1,360 lbf | Hard / Sugar Maple: 1,450 lbf | White Ash: 1,320 lbf | — |
|
Ultra-Hard Woods (Hickory / Exotic)
|
Shagbark Hickory: 1,820 lbf | Santos Mahogany: 2,200 lbf | Brazilian Cherry (Jatoba): 2,350 lbf | Ipe: 3,680 lbf | — |
|
Softest vs Hardest Known Woods
|
Balsa: 100 lbf (0.44 kN) vs Australian Buloke: 5,060 lbf (22.5 kN) | — |
|
Standard Sheet Dimensions
|
— | 4 × 8 feet (48.0 × 96.0 inches / 1219 × 2438 mm) |
|
Metric Sheet Dimensions
|
— | 1220 × 2440 mm (European & Asian standard) |
|
1/4" Category Thickness
|
— | 15/64 inch (0.234" / 5.95 mm) | Underlayment |
|
3/8" Category Thickness
|
— | 11/32 inch (0.344" / 8.73 mm) | Wall sheathing |
|
1/2" Category Thickness
|
— | 15/32 inch (0.469" / 11.91 mm) | Standard roof sheathing |
|
5/8" Category Thickness
|
— | 19/32 inch (0.594" / 15.08 mm) | Heavy-duty roof / subfloor |
|
3/4" Category Thickness
|
— | 23/32 inch (0.719" / 18.26 mm) | Standard subfloor (T&G) |