Field & trade terms
Sheathing
Sheathing is the layer of panels — plywood, OSB or gypsum sheathing — fastened to the outside of a frame to stiffen it and carry loads back into the structure. On walls it resists racking, on roofs and floors it spans between framing and ties everything together, and on the exterior it's also the base that the water-resistive barrier, flashing and cladding all attach to. How it's nailed matters as much as that it's there: the fastener pattern is what turns loose panels into a working diaphragm or shear wall.
How it shows up on site
You see wall sheathing going on over studs before the barrier, roof sheathing across rafters or trusses before underlayment, and subfloor sheathing over joists. Panels are spaced at the edges for expansion, staggered, and nailed to a schedule that gets tighter at shear walls and diaphragm edges.
What an inspector looks at
The check is panel type and thickness, edge and field nailing to the schedule, proper support and blocking at panel edges, and fasteners driven flush rather than overdriven through the face. Shear walls and roof diaphragms get the closest count because that's where the nailing does structural work.
Because RTI closes items on a photo, the nailing and panel layout are shot before the barrier and cladding cover them — edge spacing and fastener pattern in frame, the proof the diaphragm was fastened as designed.
Checklists that put sheathing to work
Free, field-ready checklists, each with the photo every item needs before it can be submitted.
Related terms
- Blocking and backingExtra framing set inside walls to give later fixtures, casework and equipment something solid to fasten into.
- UnderlaymentThe layer between structure and finish — under roofing, flooring or tile — that adds water resistance, a smooth base or the right bond surface.
- Air barrierA continuous plane of materials that stops air from leaking through the building enclosure, sealed at every joint, seam and penetration.
- Dry-inThe point at which a building is closed to weather — roof, wall barrier and openings sealed enough to keep water out and let interior work start.
- MEP (mechanical, electrical, plumbing)The mechanical, electrical and plumbing trades — the systems run through a building's structure that get inspected at rough-in and again at final.
- FirestoppingSealing openings where pipe, conduit or cable pass through a fire-rated wall or floor so the assembly's rating is restored.
Knowing the term is step one. Proving it is the job.
RTI holds the submit button until every mandatory item is answered and the photos are attached, then chains the record so it can be proven untouched later.