Roof Decking
The plywood or OSB sheathing nailed to the roof rafters that supports underlayment and shingles — the structural surface of your roof.
Quick answer
Roof Decking: The plywood or OSB sheathing nailed to the roof rafters that supports underlayment and shingles — the structural surface of your roof. Typical cost: $70–$120 per 4×8 sheet replaced; $500–$2,500 in typical hidden-damage findings on a reroof..
Why it matters
Rotted or soft decking is the #1 surprise cost on roof replacements. Most quotes assume sound decking; budget $70–$90 per replaced sheet so you aren't blindsided.
Typical cost
$70–$120 per 4×8 sheet replaced; $500–$2,500 in typical hidden-damage findings on a reroof.
Pros
- • Distributes loads to rafters
- • Provides a fastening surface for underlayment
- • Adds shear strength to the roof structure
Cons
- • Hidden from view until tear-off
- • Rots silently from small leaks
- • Replacement is rarely included in base quotes
Common uses
- • Standard residential roof construction
- • Required base for shingle, metal, and tile systems
Alternatives
1×6 board sheathing (older homes)Structural insulated panels (SIPs) in new construction
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Frequently asked questions
- How do I know if my roof decking needs replacement?
- Decking inspected during tear-off. Signs from inside: sagging between rafters, water stains, or soft spots when stepped on.
- Can decking be replaced without a full reroof?
- Usually no — replacing decking requires removing the shingles above it, so it's done as part of a reroof or major repair.
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