At One Place

OSB

Density of OSB
640 kg/m³ (600–680)
0.64 g/cm³ · 40.0 lb/ft³

Large wood strands laid in aligned layers and pressed with resin, designed as a cheaper structural replacement for plywood and rated for the same sheathing jobs. It is made from fast-growing small-diameter timber that could never be peeled into veneer, which is the economic point. Its weakness is water at the edges: OSB swells irreversibly when soaked and does not recover its thickness on drying, so cut edges on site need sealing.

Properties

Density
640 kg/m³ (600–680) — 0.64 g/cm³
Young's modulus
5 GPa
Floats in water
Yes
Magnetic
No

What it is used for

  • Roof, wall and floor sheathing
  • I-joist webs
  • Site hoarding and temporary flooring
  • Packaging cases and pallets

How it compares

Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.

air 1.2 kg/m³
expanded polystyrene foam 20 kg/m³
rigid polyurethane foam 40 kg/m³
OSB 640 kg/m³
Water — the float line 1,000 kg/m³
tungsten 19,250 kg/m³
gold 19,300 kg/m³
platinum 21,450 kg/m³
Water is 1,000 kg/m³. Anything below that floats.
Material Density Relative to water
rigid polyurethane foam 40 kg/m³ 0.04×
expanded polystyrene foam 20 kg/m³ 0.02×
air 1.2 kg/m³ 0.00×
OSB ← 640 kg/m³ 0.64×
platinum 21,450 kg/m³ 21.45×
gold 19,300 kg/m³ 19.30×
tungsten 19,250 kg/m³ 19.25×

Does it rust?

OSB contains no iron, so it cannot rust. Whether it degrades depends on the material, not on oxidation.

Is it magnetic?

OSB is not a metal and has no ferromagnetic response.

Common questions

What is the density of OSB?
640 kg/m³ (600–680), or 0.64 g/cm³.
Does OSB float?
Yes. At 640 kg/m³ it is less dense than water's 1,000.
Is OSB magnetic?
OSB is not a metal and has no ferromagnetic response.

Related pages

Sources

  1. Typical range compiled from manufacturer specifications — At One Place

How these figures are compiled and checked