What roof decking means
Roof decking is the structural layer of plywood, OSB or boards nailed to the rafters or trusses. The underlayment and roofing go on top of it.
Also called roof deck, roof sheathing.
Where it matters on a roofing job
You only see the deck after tear-off, which is why rotten decking is the most common change order on a reroof. Put a per sheet price for decking replacement in the estimate up front, so swapping bad sheets is a known number and not an argument on the roof.
What the model code says
- The code defines the roof deck as the flat or sloped surface, not counting its supporting members. (IRC 2021, Chapter 2)
Check which code edition your building department enforces for roof decking before you quote.
What it costs
Koira's roof replacement cost guide puts a typical job at $9,350, with most between $5,800 to $13,000. The guide shows its sources and what moves the price. The plywood and sheathing calculator prices a job line by line.
Work it out
- Free calculator: Plywood and sheathing calculator
- Cost guide: Roof replacement cost
- Free template: Change order template
- Licensing: Roofing license rules by state
- Tools, templates and guides: Free roofing resources
Sources: 2021 International Residential Code, Chapter 2, Definitions (ICC). Checked October 9, 2026.