OSB vs plywood for subfloor — which is better?

Both are code-compliant and perform well. Standard OSB is 20-30% less expensive than plywood. Plywood handles moisture better and recovers its shape after getting wet, while standard OSB can swell permanently at the edges. Premium OSB like AdvanTech bridges this gap with excellent moisture resistance at a price between standard OSB and plywood.

What thickness subfloor do I need?

Use 23/32-inch (3/4 inch) panels for 16-inch on-center joist spacing, which is the most common residential configuration. For 24-inch spacing, step up to 7/8-inch or 1-inch panels to prevent deflection and bounce. If installing tile or stone flooring, use the thicker panels regardless of joist spacing.

How many OSB panels do I need for my floor?

Divide your total floor area in square feet by 32 (the area of one 4x8 panel) and add 10% for waste from cuts and edges. A 1,200 sq ft floor needs about 38 panels net, or 42 panels with waste. Order full sheets — partial panels from cuts can often be used for closets and small areas.

Do I need tongue-and-groove subfloor panels?

Tongue-and-groove (T&G) edges are strongly recommended for subfloor panels. The interlocking edges eliminate differential deflection between panels, reducing squeaks and creating a stiffer floor. Most builders consider T&G panels standard practice even though square-edge panels are technically code-compliant.

How do I install OSB subfloor panels?

Lay panels with the long edge perpendicular to the floor joists, stagger end joints by at least one joist bay between rows, and leave 1/8-inch expansion gaps at all edges. Apply subfloor adhesive to the joists, set the panel, and fasten with ring-shank nails or screws every 6 inches on edges and 12 inches in the field.

Can OSB subfloor get wet during construction?

Exposure 1-rated OSB can handle brief weather exposure during construction, but standing water should be swept off promptly. Standard OSB edges swell when saturated and do not return to their original thickness. If extended rain exposure is expected, use AdvanTech or CDX plywood, which handle moisture significantly better.

OSB Panel Calculator

How many OSB sheets do I need? Free calculator for 1200×2400 mm subfloor panels — accounts for waste and gives exact sheet count.

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Enter Your Measurements

How to Use This Calculator

1Measure total floor area in square feet (length × width).
2Click Calculate — each 4x8 panel covers 32 sq ft.

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About This Material

OSB (Oriented Strand Board) subfloor panels are the standard structural subfloor material in modern residential construction. Standard panels are 4x8 feet (32 sq ft each) with tongue-and-groove edges for a tight, squeak-free fit. The most common thickness is 23/32 inch (marketed as 3/4 inch) for 16-inch joist spacing, while 7/8-inch or 1-inch panels are used for 24-inch spacing or heavy loads like tile and stone. Premium brands like AdvanTech offer superior moisture resistance and a 500-day no-sand guarantee. Standard OSB subfloor costs $25 to $35 per sheet, while premium moisture-resistant panels run $35 to $50. CDX plywood is an alternative that handles moisture better than standard OSB but costs more. Always use panels rated Exposure 1 or better, as subfloor panels may be exposed to weather during construction. Panels carry a span rating printed on the grade stamp indicating maximum joist spacing.

Next Steps:

Subfloor Adhesive Calculator →Floor Joist Calculator →Bottom Plate Calculator →

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