This calculator prices roof decking (sheathing) from four inputs: home footprint, pitch, percent of deck being replaced, and panel material. It converts footprint to roof area with a pitch multiplier, applies the replacement percentage, adds 10% waste, and divides by 32 sq ft per 4×8 sheet. A medium (2,000 sq ft) home at standard pitch replacing half its deck in 7/16" OSB needs 41 sheets and runs roughly $2,300–$4,300 installed.
How this calculator sizes your decking job
Decking — also called sheathing — is the layer of wood panels nailed across the roof frame that everything else attaches to. This calculator starts from your home's ground-level footprint, not a roof measurement, because most homeowners know the footprint and not the roof surface area. It converts one to the other with a pitch multiplier: 1.03 for a low-slope roof, 1.12 for a standard-pitch roof, and 1.25 for a steep roof. Multiply footprint by that factor and you have the roof's actual surface area.
The replacement percentage matters because full tear-off is rare. Most decking jobs are discovered mid-reroof, when a crew pulls old shingles and finds soft or delaminated panels in specific areas — this calculator lets you model 25%, 50%, 75% or 100% of the roof rather than forcing a full-replacement estimate on a partial repair.
Reading a panel's span rating
Every OSB or plywood panel sold for roof sheathing carries a span rating printed on its face — two numbers separated by a slash, such as 32/16. According to the APA – The Engineered Wood Association, the first number is the maximum support spacing approved for roof sheathing and the second is for subflooring. A 32/16 panel can span roof rafters or trusses up to 32 inches on center; the same panel is only rated to 16 inches on center if it were used as a subfloor instead. Some roof spans also require panel-edge support (clips or blocking between supports) to hit the rated span — check the stamp, not just the thickness.
What the rating does not tell you, on its own, is exactly which thickness you need for your rafter spacing — that mapping sits in APA's engineering tables and depends on load, spacing, and edge support together, so it is not something to eyeball from a general chart. Your inspector or the panel's own stamp is the authority; this calculator's material choices (7/16" and 5/8" OSB, 1/2" and 5/8" plywood) reflect what a supplier stocks, not a specific span you're cleared for. If you don't know what your existing deck is rated for, matching the thickness already on the roof is the safest default.
What drives labor cost by region
Decking is usually replaced by the same roofing crew doing the tear-off, so its labor cost tracks the same wage data as the rest of the job. The Bureau of Labor Statistics puts the mean hourly wage for roofers (SOC 47-2181) at $27.95 as of May 2025, with a 10th-to-90th percentile spread of $18.01 to $39.29 an hour — more than double from one end of the market to the other. Florida (23,550 roofers) and California (21,190) employ close to a third of the national workforce; in thinner markets like Washington (5,890) or Illinois (5,300), a small decking-only callout competes for crew time against full reroofs, which can push both price and lead time up independent of the wage rate.
It's worth knowing where decking sits in the cost of a whole house. NAHB's 2024 Cost of Constructing a Home survey breaks total construction cost into eight stages; framing — which includes roof sheathing — is the third largest at 16.6%, behind interior finishes (24.1%) and major system rough-ins (19.2%). NAHB does not publish a standalone roofing or decking dollar figure inside that framing share, so that 16.6% is the most granular sourced context available; it is not a per-project decking cost.
What this estimate excludes
This is a decking-and-labor price, not a roof price. A few things routinely show up on the invoice that this tool does not model:
- ·Structural framing repair. If rafters or trusses are rotted under the deck, that's carpentry work priced separately — see the roof truss calculator for the framing side.
- ·Underlayment and shingles. Decking is the substrate; everything installed on top of it, starting with underlayment, is priced on its own page.
- ·Discovering more damage than expected. The replacement percentage you pick is a pre-tear-off estimate. Contractors typically can't confirm the real number until the old roofing is off.
- ·Permit fees. Decking replacement bundled into a full reroof usually triggers the same permit as the roofing job; set fees vary by jurisdiction and aren't modeled here.
There is also no federal data series to check any of this against independently. The U.S. Census Bureau's Characteristics of New Housing (CHARS) survey tracks square footage, bedroom and bathroom counts, and exterior wall material for new single-family homes — it does not track roofing or decking material at all, confirmed on both the CHARS landing page and its 2025 Highlights page. Every decking price you'll find, including this calculator's, is built from supplier and contractor pricing, not a government benchmark.
How to read a contractor's decking line item
Decking is one of the easiest line items to sanity-check because it's priced by a countable unit — the sheet.
- Does the quote state a sheet count and a per-sheet price, or just a lump sum? A lump sum hides whether you're being charged for 25% coverage or 100%.
- Is the per-sheet price inside a normal band for the stated material and thickness? This calculator's own bands run $25–$40 for 7/16" OSB up to $45–$75 for 5/8" plywood — a quote far outside that range, high or low, is worth a question.
- Does the estimate include a waste allowance? A quote with a sheet count suspiciously close to the exact square footage divided by 32, with no cushion, likely hasn't accounted for cut waste and will change once the crew is on the roof.
A quote that comes in well above this page's total most often reflects a bigger discovered percentage of bad decking, not a padded price — which is exactly why the finding shouldn't be treated as a surprise fee if the contractor documents it with photos before replacing it.
Who does the work, and what that costs
Decking replacement is priced by the same crew already on the roof, which is why it is almost always quoted as a line item inside a re-roof rather than as a standalone job. The Bureau of Labor Statistics puts the annual mean wage across all construction and extraction occupations at $65,360 as of May 2025, against $58,140 for roofers specifically. Roofing sits below the trade average, and sheathing work is the part of a re-roof most likely to be handed to a carpenter at the higher rate.
That matters for reading a quote. A contractor who finds soft sheathing mid-tear-off is repricing the job on the day, with the roof open and the homeowner holding no leverage. Getting the per-sheet replacement price in writing before work starts — this calculator gives you the material half of it — is the most useful thing you can do with this page.
Methodology
Sheet counts and cost bands are read directly from this calculator's own module: pitch multipliers (1.03 low / 1.12 standard / 1.25 steep), a 10% waste factor, 32 sq ft per 4×8 sheet, and per-sheet material prices for 7/16" and 5/8" OSB and 1/2" and 5/8" plywood. Labor is priced per square foot of area replaced. Wage and span-rating context is drawn from the sources below; no thickness-to-span mapping is published because APA's detailed span tables could not be independently verified.
Sources
- APA – The Engineered Wood Association — OSB / Oriented Strand Board — accessed 2026-09-05
- U.S. Bureau of Labor Statistics — OEWS Profile, Roofers (47-2181), May 2025 — accessed 2026-09-05
- NAHB / Eye on Housing — Cost of Constructing a Home, 2024 survey — accessed 2026-09-05
- U.S. Census Bureau — Characteristics of New Housing (CHARS) — accessed 2026-09-05
- U.S. Bureau of Labor Statistics — Occupational Employment and Wage Statistics, May 2025 — accessed 2026-09-05