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Materials & Specificationsaka: wall sheathingaka: roof sheathingaka: roof deckingaka: OSB sheathing

Sheathing

In Plain English

The structural panel layer applied to wall and roof framing that provides rigidity and a surface for exterior materials.

Definition

Sheathing is structural panel material — typically plywood or OSB — applied to the exterior of wall and roof framing to provide structural rigidity, lateral bracing, and a substrate for exterior cladding and roofing. Roof sheathing is also called decking. Sheathing is commonly covered with a weather-resistant barrier before cladding is applied.

Why It Matters in Bidding

Sheathing is a high-quantity line item where small unit-price and waste-factor decisions compound across thousands of square feet, so accurate takeoff from elevations and roof plans directly drives material budgets. Estimators also have to price the labor split between framing crews and the choice between plywood and OSB, since spec-driven thickness, nail schedules, and shear-wall requirements change both cost and the sub's scope boundaries.

Example

An estimator pricing a 2,800 SF roof adds a 10 percent waste factor to the sheathing takeoff and confirms the shear-wall nailing schedule on the structural sheets before locking in the framing sub's number.

Related Terms

PlywoodOriented Strand BoardCladdingFiber Cement

Frequently Asked Questions

Take off wall and roof areas from the plans, deduct large openings, then divide by panel coverage (32 SF per 4x8 sheet) and add a waste factor, usually 5 to 15 percent depending on cut complexity, hip and valley counts, and panel orientation. Confirm thickness and span rating against the structural drawings.
Bid whatever the specifications require; substituting without approval risks a rejected submittal and rework. When the spec allows either, OSB is typically lower in material cost while plywood handles moisture and re-nailing better. Note any value-engineering substitution as a clarified alternate rather than burying it in your base number.
It is almost always carried within the rough framing subcontractor's scope, since the same crew installs it. Estimators should still verify the scope letter explicitly includes wall, roof, and floor sheathing plus the specified fasteners, because gaps here create scope-gap change orders after award.

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