'Decking as needed' is how contractors hide $3,000 of guesswork inside your roof bid. I walk-probe every accessible plane, inspect the underside from the attic, and give you a per-sheet estimate with photos — so your bid has a real number and your contractor can't invent decking damage on strip-off day.
Walk-probe every accessible slope for soft spots, sponginess, and rafter sag
Attic underside inspection with flashlight and moisture meter for dark staining and delamination
OSB vs plywood identification (delamination behavior is different) with per-sheet score
Moisture mapping with pin and pinless meter readings (documented %MC per sheet)
Repair vs full-replace scope with cost-per-sheet math and IRC nailing pattern notes
Contractor-bid template: sheet count, locations, and photos so 'TBD decking' becomes a real line item
Walk-inspection of every accessible slope for soft/spongy decking and rafter deflection. Attic-side inspection with flashlight and moisture meter — dark staining, frost damage, fungal growth, and delamination. OSB vs plywood identification and behavior notes — OSB delaminates in layers, plywood usually just softens. Moisture meter readings (pin + pinless) at suspect locations, documented in %MC. Sheet-by-sheet map: numbered locations, photos, meter readings, and repair recommendation. Written scope: spot repair count vs full re-deck scope, with cost-per-sheet math and IRC / IBC code nailing pattern notes.
Homeowners who've been quoted a re-roof with vague 'decking as needed' language. Homeowners who feel soft spots when walking the roof or see sagging between rafters. Buyers on homes with active or historical leaks who need to scope hidden decking damage. Owners with attic staining or dark spots on the deck underside. Insurance policyholders whose claim was denied — hidden rot from long-term leaks can requalify.
Standard Sheathing Probe Report — $349 Detailed w/ Per-Sheet Moisture Mapping — $549 Bid-Ready Scope (contractor template + photos) — $649 Add to any existing inspection — $199 Most sheathing inspections are $349–$549. Catching 4 rotted sheets before signing a bid that includes 40 saves $1,000+ nearly every time.
You mostly don't from the ground. Soft spots underfoot on the roof, sagging between rafters, dark stains on the underside of the decking in the attic, and delaminated OSB that flakes like a book — those are the clues. I probe every accessible plane and map soft spots to a sheet-by-sheet estimate you can put in a bid.
That 'TBD' language is how you get billed for 40 sheets when you needed 4. I probe and mark suspect sheets before you sign, and my report gives the contractor a specific per-sheet count with photos. If they find more once the roof is stripped, they document it — but the baseline is set and you're not paying blind.
Under 15% of the deck rotted + isolated to a slope = spot repair. Widespread delamination, sagging between rafters, or moisture across multiple slopes = full replacement. I score it per-slope, include the code jump for a full re-deck (Zone 3 wind-uplift nailing pattern under IRC), and give you both scopes with real numbers.
Bid + scope compared line-by-line.
Hail/wind + NOAA event correlation.
Map wet insulation before you recoat.
IRC / IBC / NMCID cited per finding.
I've watched too many neighbors sign contracts they didn't understand for roofs they didn't need. That stops with a written report they own.