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Roof Decking Calculator
Calculate roof decking costs by material and replacement area. Compare OSB and plywood with installation labor.
Educational calculators — always consult a licensed professional before making financial decisions.
Home footprint under 1,500 sq ft. Actual decking area is larger after pitch factor; add 10–15% for waste.
Minimum thickness for most residential codes. Suitable for standard shingles on 24" rafter spacing. ~$20–$25/sheet.
Low pitch has minimal area increase from footprint. Closer rafter spacing often required for heavy materials.
Localized rot or damage around a leak area. Spot replacement is most cost-effective.
Total Decking Cost
$730 – $1,440
330 sq ft of replacement area
Cost Breakdown
Where Your Money Goes
Actual decking needs are determined during tear-off. Budget 10–15% extra for soft spots discovered during the job.
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What you'll need
- ·Total roof area in square feet
- ·Decking material — OSB or plywood
- ·Estimated percentage needing replacement
What you'll get
- ✓Material cost — OSB vs. plywood by thickness
- ✓Installed cost — Material plus installation labor
- ✓Sheet count — Based on your replacement area
- ✓Total project cost — Scaled to your replacement percentage
How it works
Enter roof area
Input total roof area in square feet or use the roof area calculator first.
Choose material
Select OSB (oriented strand board) or plywood — OSB is cheaper, plywood is stronger.
Set replacement percentage
Partial replacement (damaged sections only) is common — set your estimated coverage.
Roof Decking Cost by Material
| Material | Thickness | Material/Sheet | Installed/Sq Ft |
|---|---|---|---|
| OSB 7/16" | 7/16" | $18–$30 | $2.00–$3.50 |
| OSB 5/8" | 5/8" | $25–$38 | $2.50–$4.00 |
| Plywood 1/2" | 1/2" | $30–$45 | $3.00–$5.00 |
| Plywood 3/4" | 3/4" | $40–$60 | $3.50–$6.00 |
Full replacement typically needed when more than 25% of deck is damaged or rotted.
About this calculator
How much does roof decking replacement cost?+
Roof decking replacement costs $70–$100 per 4×8 sheet of OSB installed, or $90–$130 per sheet of plywood installed. Full roof decking replacement on a 2,000 sq ft home costs $2,500–$5,500 depending on material and labor rates. Partial replacement of damaged sections runs $200–$1,000 per area.
OSB vs plywood roof decking: which is better?+
OSB (oriented strand board) is less expensive ($30–$45 per sheet) and is the standard for new construction. Plywood ($45–$70 per sheet) is stronger, holds fasteners better, and handles moisture more forgivingly. For re-roofing over existing decking, matching the original material is usually fine. For areas with high humidity or potential moisture exposure, plywood is the better choice.
When does roof decking need to be replaced?+
Replace roof decking when you find soft spots or sagging when walking on the roof, visible rot or mold, water damage with staining or swelling, delamination (layers separating), or when the wood crumbles rather than holding nails. During a re-roof, contractors inspect all decking and replace damaged sections. Expect 5–15% decking replacement on older roofs.
Is roof decking included in a roof replacement quote?+
Most roof replacement quotes include a small allowance for decking replacement (typically 2–5%). Additional damaged decking discovered during the job is usually billed separately at $3–$5 per sq ft. Always clarify with your contractor what is included and the per-sheet rate for additional decking before signing the contract.
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Back to the calculator ↑Roof Decking Calculator is built and maintained by the RealCostIQ editorial team. Cost ranges and rates are checked against published industry data and contractor quotes, and revised when the underlying figures move. Read our data methodology or more about who builds this. Every calculation runs in your browser — no account, and none of your inputs are stored.
Cost ranges and rates here are checked against contractor quotes and published industry data. If a number still looks off, email Support@RealCostIQ.com and we'll review and fix it.